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Headshaking in horses: New treatment has 50% success rate

Headshaking syndrome is when a horse shakes or jerks its head uncontrollably for no apparent reason. There are striking clinical similarities between facial pain syndromes in people, most notably trigeminal neuralgia, and headshaking in horses. Although some progress has been made towards both diagnosing and treating the condition in horses, the pathology of the disease remains unknown and further research is needed. A recent study led by academics from the University of Bristol’s School of Veterinary Sciences and the University of Liverpool, evaluated the long-term success rate of a pioneering new surgical procedure, called caudal compression of the infraorbital nerve, where platinum coils are placed into the nerve ends within the canal to relieve the pain. The study found this surgery could be a viable option for headshaking in horses with a long-term success rate of nearly 50 per cent. Nonetheless, researchers are continually working to find a more effective treatment method for headshaking.

Veronica Roberts, Clinical Fellow in Equine Medicine in the University’s School of Veterinary Sciences, who led the study, has received a grant from the British Neuropathological Society to investigate possible focal demyelination of the nerve as a cause of headshaking in horses. The reason the Bristol research team is looking for demyelination is that it is the most common cause of trigeminal neuralgia in people. The team will collaborate with Seth Love, Professor of Neuropathology in the School of Clinical Sciences, as he has carried out work in this area in people. To find a more effective treatment and to understand the disease, Veronica is requesting that anyone who is considering euthanizing a horse due to headshaking to contact her for possible inclusion in her study. The study published in Equine Veterinary Journal evaluated the long-term success rate of caudal compression of the infraorbital nerve, the researchers reviewed clinical records of 58 horses that underwent this surgery between June 2004 and January 2011. The horses, aged one to 17 years, were used for general riding, show jumping, eventing, or dressage and had a history of headshaking. The study found: Surgery was initially considered a success in 35 of 57 (63 per cent) horses, but headshaking recurred between nine and 30 months later in nine horses. The research team repeated the surgery in ten horses; nose rubbing resolved in all but four horses that were later euthanized. Veronica Roberts said: “There are striking clinical similarities between facial pain syndromes in people, most notably trigeminal neuralgia, and headshaking in horses.

“Headshaking in horses is a major welfare issue for horses and more research is needed on the aetiopathogenesis of this pain syndrome to improve medical and surgical therapies. Headshaking is a significant cause of distress for some horses and this treatment in selected cases is needed even though the failure rate is limited.” The researchers concluded from their study that the caudal compression procedure offers the best prognosis for a successful outcome compared with other treatments for horses where the only alternative is euthanasia. However, surgical treatment of the disorder needs to be improved together with further research into the pathogenesis of the disorder.

Science Daily
November 27, 2012

Original web page at Science Daily

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Psychology of equine performance and the biology behind laminitis

Achieving the best performance from a horse is the goal of not just professional riders, but also the millions of amateur and hobby riders all over the world. A new article published in BioMed Central’s open access journal BMC Veterinary Research looks at the issues surrounding training, competition environment and practices, and how the psychology of horse mood, emotion and temperament can be used to enhance performance. A sister article looks at the devastating disease laminitis, and finds that the anti-inflammatory protein apolipoprotein A-IV (APOA-IV) is raised in chronic laminitis, which suggests that it is linked to a more general inflammation, especially of the digestive system. Laminitis is a painful and debilitating disease. Although the exact cause is unknown it is often associated with insulin resistance and obesity, and can be preceded by diseases such as colic and diarrhea. It is known to occur in horses allowed the freedom to eat lots of lush fresh, grass especially after being kept indoors for the winter. Inflammation can lead to irreversible rotation of the foot bones inside the hoof. In 75% of cases the inflammation becomes chronic ‘founder’, leaving the horse permanently lame.

Prof Bhanu Chowdhary and Dr Samantha Steelman from the College of Veterinary Medicine, Texas A&M University, found 16 proteins which have different levels in the blood of horses with and without chronic laminitis. Horses in both groups were in good health apart from the laminitis. Eleven of these proteins are involved in response to wounding, coagulation and inflammation, such as coagulation factor X. The remaining proteins included fetuin A and B, both of which are involved in acute immune response, immunoglobulin, an indicator of increased antibody levels, and most importantly APOA-IV. Dr Steelman explained, “APOA-IV is produced by the small intestine — one of its functions is to tell the animal when it is full. It also has anti-oxidant and anti-inflammatory properties, which might explain the raised levels of APOA-IV.” In a comprehensive review of psychological factors affecting equine performance Dr Sebastian McBride from the Royal Agricultural College and Prof Daniel Mills from the University of Lincoln have looked at how current behavioral research and already established behavioral modification techniques could be applied to enhance the performance of animals at competition level. This includes matching a horse’s temperament to different equestrian disciplines, for example, flightiness can be good for racing but detrimental for dressage. Dr McBride commented, “Another important consideration is the horses mood and emotional reaction. Although all of these have an intrinsic baseline observable in the young, untrained horse, they can be influenced by training and they are also dependent on the interaction between rider and horse. Competition riders are well aware how a strange environment, and nerves on competition day, can affect their horse’s performance.” Prof Daniel Mills continued, “The increased competitiveness and performance level of equestrian sport means that for each horse and rider pair physical and psychological behavior must be taken into consideration when designing training conditions and increasing motivation to perform at the optimum level of athletics. They must also be applied to reducing over-emotional reactions on competition day and, given the trained horse’s high motivation to succeed, to decrease any negative experiences at competitions which may otherwise impact on future events.”

Science Daily
October 16, 2012

Original web page at Science Daily

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Horse gait traced to single mutation

A single gene mutation in horses can endow them with a wider repertoire of gaits. The finding, reported this week in Nature, shows that some seemingly complex physical traits can have a simple genetic basis. It could also shed light on the genes behind movement disorders in humans. Horses usually have three styles of gait — walk, trot and gallop. But certain breeds can perform extra gaits, such as pacing, in which the legs on one side of the body move together. Breeds such as the American Standardbred and some Icelandic horses can pace, which is useful in certain types of racing. Researchers led by Leif Andersson, a geneticist at Uppsala University in Sweden studied the genomes of 70 horses that could perform extra gaits — 40 could pace, and 30 could perform other alternate gaits. The analysis revealed a single mutation common to all the horses that could pace, in a gene called DMRT3. Both copies of that gene in the pacing horses were mutated. Having such detailed information about horse gaits was key to the gene hunt — horse breeders and researchers wouldn’t have spotted this if they had categorised gaits more loosely. “What they’ve done so nicely is really thought carefully about how to classify phenotype,” says Elaine Ostrander, who studies the genetics of domesticated animals at the US National Human Genome Research Institute in Bethesda, Maryland. This fine-grained information about gait styles makes the genetic link clear, she says. “They got a screamingly hot result.”

“It sounds like quite a complicated trait, the control of gait,” says Andersson. But in this case, the result was simple. “We thought it was too good to be true at first. But we were able to confirm it.” Hear how a single mutation bestows extra gaits on some horses, as Leif Andersson talks to Kerri Smith. Go to full podcast to verify the gene’s link to locomotion, the researchers studied its function in mice, and found that mice with no functional copy of the gene had trouble coordinating their limbs. Further, the gene was found to be expressed in cells in the mouse spinal cord that connected to motor neurons. Horses without this mutation cannot move their right hindleg and right foreleg forward at the same time, Andersson says. But with the mutation, which shortens the encoded protein by about one-third, “the regulation of the movement isn’t so strict anymore, and becomes more flexible,” he says. The work could provide a basis for studies of human disorders, says Ostrander. Her own work on the genetics of skull formation in dogs is providing hints of the genes implicated in human disorders that feature similar phenotypes. Genes linked to specific physical characteristics or behaviours can provide clues to the genetic basis of human syndromes. The relationship between a mutation and the resulting phenotype may not be as simple in humans as in gaited horses, but walking difficulty is a common symptom of many neuromuscular disorders. “This gene will slide into the puzzle of one of those human syndromes, for sure,” Ostrander says.

Nature
September 18, 2012

Original web page at Nature

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Scientist creates test, treatment for malaria-like sickness in horses

When Washington State University and U.S. Department of Agriculture veterinary scientist Don Knowles got word two years ago that a rare but deadly infection was discovered among a group of horses in south Texas, he felt a jolt of adrenaline. Not only were the horses infected with a parasitic disease similar to malaria in humans, but the epicenter of the outbreak was at no ordinary ranch. It was the King Ranch, legendary for its world-class quarter horses, including former winners of the Triple Crown and Kentucky Derby. The 825,000 acre family-owned estate that stretches across four counties is one of the largest and most famous ranches in the world. “Anyone who knows anything about quarter horses knows about this ranch,” said Knowles. “Universally, it’s on the map for the best horses and cattle.” One King Ranch horse had tested positive for the disease when the federal government first alerted Knowles. A few days later, it was a dozen; then four dozen. “The number just kept going up,” recalled Knowles at his WSU office, where a large photograph of Appaloosa horses in a field punctuates one wall and a road bike leans against another. Knowles, in his silver-rimmed spectacles, hiking shorts and athletic shoes, resembles someone more at home on a bike trail than a scientist at the beck and call of deadly, infectious animal diseases that pull him to regions near and far. “This kind of outbreak had never been seen in this country before,” he said. “People were asking ‘What’s going on down there?'”

And so, at the request of federal agriculture officials, Knowles boarded a plane and headed south to investigate. As leader of the USDA’s Animal Disease Research Unit at WSU, he had a Texas-sized riddle to solve. Equine piroplasmosis is so feared in the U.S. that the government bans horses that test positive from entering the country. Until the outbreak in Texas, only a few sporadic cases had ever been reported. “We had regarded piroplasmosis as a foreign animal disease and suddenly here it was on U.S. soil, with not one or two cases but nearly 300 — all concentrated at a ranch recognized for exemplary management practices,” said Dudley Hoskins, an attorney with the American Horse Council in Washington, D.C., at that time. “To say we were concerned would be an understatement.” Piroplasmosis, also called equine tick fever, is transmitted to horses through the bite of a tick that carries either the Babesia caballi or Theileria equi parasites in its saliva. Similar to malarial parasites that infect humans, these pear-shaped creatures travel through the horse’s circulatory system, multiplying, drilling through red blood cells and multiplying some more. Knowles, also a professor of microbiology and pathology at WSU’s veterinary college, teaches his students about it.

“I tell them that one of their responsibilities as a veterinarian will be to prevent piroplasmosis and how an outbreak could result in a great loss of horses and deal a severe blow to the horse industry,” he said. “Once the parasite becomes established in the tick and equine population, it could spread quickly as horses are transported to equestrian shows and races around the country.” Many infected horses exhibit little more than cold-like symptoms, but in regions where piroplasmosis is uncommon — such as the U.S. — horses have no natural resistance to the disease. Unimpeded, the parasites proliferate and destroy blood cells, triggering fever, anorexia and anemia. “If a horse dies of piroplasmosis, anemia is often the cause,” said Knowles. “It’s a progressive process and a miserable way for an animal to die.” Before the outbreak in 2009, no standard treatment existed. If a horse tested positive for piroplasmosis, the owner had three government-mandated options to keep the disease from spreading: euthanize, quarantine or ship the horse out of country. “Our horses are vitally important to us,” said King Ranch manager Dave Delaney by cell phone from the ranch, 45 miles southwest of Corpus Christi. “The idea of euthanizing them was out of the question.

“Many of us had heard of piroplasmosis but had never dealt with it,” he said. “So when Don got here, whenever he spoke, believe me, people paid attention.” Long before Knowles boarded that Texas-bound plane in autumn 2009, he knew a lot about piroplasmosis. The periodic clusters that surfaced in temperate-climate states such as Florida proved the parasites sometimes slipped across the U.S. border in horses that had tested negative for the disease when, in fact, they were positive. Because the test sometimes gave false negatives, Knowles was charged with developing a more reliable diagnostic test. He also was instructed to create a standardized treatment to kill the parasites. “Until Texas, much of the work had been done in the lab,” he said. This means that, after Knowles and his team arrived at King Ranch, “you might say we provided him with a real-world case to test the effectiveness of his preliminary work,” said Delaney. Armed with two decades of piroplasmosis research and a team of scientists from his USDA unit and WSU, Knowles not only contained the outbreak but he and colleague Glen Scoles also identified a new blood-sucking culprit that had spread it. “Prior to that outbreak, we knew of two tick species capable of transmitting the disease. There, we discovered a third,” said Knowles. He and his team identified the cayenne tick as the predominant carrier, a finding so important that the group later published a paper about it in the journal Emerging Infectious Diseases. It’s likely a cayenne tick snagged a ride on an infected horse years before the outbreak, drawing parasites in through its blood meal then moving on, injecting and infecting other horses, said entomologist Scoles who, after the outbreak, proved that the cayenne species was involved.

The outbreak at King Ranch “could have coincided with climate factors which, in turn, caused an increase in tick numbers,” said Scoles. All said and done, Knowles and his team did more than identify a new eight-legged transmitter of piroplasmosis and develop an internationally accepted test to diagnosis it. “How about, ‘They saved our horses?’ ” said Delaney of King Ranch. With high doses of imidocarb dipropionate, a drug used to treat certain diseases in cattle, “The parasites appear to be eradicated. All of our horses are healthy,” he said. The outcome of administering the drug was so successful that, after subsequent trials, it is now being evaluated as a standard treatment protocol in the U.S. “If approved for use, the treatment would offer a way to clear horses of infection,” said Hoskins, who has followed Knowles’ research. “This would be huge.” Which means that, largely because of Knowles’ work, the owner of a piroplasmosis-infected horse may have the option of curing the animal — and then one day watching it flash across a meadow or even a finish line.

Science Daily
September 18, 2012

Original web page at Science Daily

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Horse racing: Doping detection stays a neck ahead

Whilst the eyes of the world may currently be focused on the Olympics, human sport is not the only area where drug testing is routinely carried out. Horse racing is a massive world-wide industry, and regular testing is essential to maintain its integrity. As with human sport, the authorities constantly need to develop methodologies to detect new compounds that drug cheats are using or may start to use. One such compound is peginesatide. Peginesatide is the first representative of a new class of compounds that mimic the effects of erythropoietin; these include an increase in the number of red blood cells and of haemoglobin levels in the blood. Both of these increase endurance and so-called erythropoiesis-stimulating agents (ESAs) are banned in human and equine sports. The approval of the use of peginesatide by the US Food and Drug Administration (FDA) to treat anemia in patients on dialysis increases its availability and the chance of its use in illegal performance enhancement.

A new mass spectrometry method for detecting peginesatide in humans has already been developed, and now the extension of this for the detection of peginesatide in horse serum is described in an article published in EJMS — European Journal of Mass Spectrometry written by Ines Möller, Andreas Thomas, Anke Wingender, Marc Machnik, Wilhelm Schänzer and Mario Thevis from the German Sport University Cologne, Germany. This is timely since the German Equestrian Federation has recently added peginesatide to its prohibited substance list. The new method uses electrospray ionisation (ESI) liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples are prepared using the serine endopeptidase subtilisin to break down the compounds in the sample prior to LC-MS/MS analysis. According to lead author Mario Thevis, “The method is precise, specific and linear over a wide concentration range. Further, being simple, fast, cost effective, easily transferable to other laboratories and in accordance with the criteria for ‘identification by chromatography and mass spectrometry’ outlined by the Association of Official Racing Chemists (AORC), the method is suitable for routine use in the horse sports drug testing arena.”

Science Daily
August 21, 2012

Original web page at Science Daily

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Whence the domestic horse?

To study the ancestor of domesticated horses, scientists gathered genetic data from horses around Europe that had been shaped the least by human breeding, such as this animal in Kyrgyzstan. Shards of pottery with traces of mare’s milk, mass gravesites for horses, and drawings of horses with plows and chariots: These are some of the signs left by ancient people hinting at the importance of horses to their lives. But putting a place and date on the domestication of horses has been a challenge for archaeologists. Now, a team of geneticists studying modern breeds of the animal has assembled an evolutionary picture of its storied past. Horses, the scientists conclude, were first domesticated 6000 years ago in the western part of the Eurasian Steppe, modern-day Ukraine and West Kazakhstan. And as the animals were domesticated, they were regularly interbred with wild horses, the researchers say. “This is a very good paper,” says biologist Michael Hofreiter of the University of York in the United Kingdom. “Nobody has applied this method of population modeling to horses before.”

Throughout their history, horses have been interbred, traded between populations of people, and moved across continents. All of this makes their genetic history hard to follow. Moreover, the wild ancestor of horses, Equus ferus, is extinct, complicating researchers’ efforts to compare the genetics of domestic animals with wild ones. Previous research nailed down a broad area—the Eurasian Steppe, which stretches from Hungary and Romania through Mongolia—as the region where horses originated and were domesticated. But earlier genetic studies relied mostly on mitochondrial DNA, which is inherited only from a mother, to try to understand horses’ evolutionary history. “The problem was that there was a lot of diversity in the mitochondrial DNA,” says biologist Vera Warmuth of the University of Cambridge in the United Kingdom, the first author of the new study. And the diversity didn’t group the horses into their breed or place of origin. “Every horse breed has almost all the mitochondrial lineages represented,” she says. Warmuth instead studied sequences of horse DNA inherited from both parents and known to be diverse between horse populations. She and her colleagues collected genetic samples from more than 300 horses at 12 different sites across the steppe. Data were collected for only working animals bred within a local area, not those bred for show or appearance, to minimize any human-guided selection that would make some genes more common. Then, the researchers used computer programs designed to model the spread of a population to simulate how different locations of horse domestication and spread throughout the steppe would influence modern genetic diversity. They compared each model with the real data they had collected to see which fit best.

The best-fit model, the team reports today in the Proceedings of the National Academy of Sciences, showed the wild ancestor of domestic horses originating in eastern Eurasia 160,000 years ago and being domesticated in the western part of the Eurasian Steppe around 6000 years ago. The model also helped explain why there had been so many female lineages when previous studies had tried to rely on mitochondrial DNA. “We think that as domestic horses spread out of the western steppe, local wild females were continuously incorporated into the spreading herds,” says Warmuth. The constant addition of new females made the genetic patterns—in particular, the female lineages—more complex than if the domestic population had been totally isolated. Hofreiter is impressed. “They have still only narrowed down the domestication region to a fairly big area,” he says, “but they did have enough genetic data to get a signal out of the noise.” Not all researchers are convinced, however. Archaeologist Marsha Levine of the University of Cambridge thinks using modern genetic samples to retrace horses’ evolution is a dead end. “There’s been mixing of cultures and mixing of horses in this region for many thousands of years,” she says. “And so when you’re looking at any modern horse, you just don’t know where it’s from.” Bringing together many kinds of evidence is what will ultimately answer the whens and wheres of horse domestication, Levine says. “What we need to be doing is using material from excavations, sequencing ancient genes, and combining that with what we know from archaeological evidence about how animals were used in the past.” Ultimately, says Hofreiter, getting to the bottom of horse domestication will reveal more than just the history of these animals. “Horse domestication has changed human cultures a lot. It has changed warfare, it has changed transportation,” he says. “Studying the past of horses can tell us a lot about our own past.”

ScienceNow
May 29, 2012

Original web page at ScienceNow

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How the Quarter Horse won the rodeo

American Quarter Horses are renowned for their speed, agility, and calm disposition. Consequently over four million Quarter Horses are used as working horses on ranches, as show horses or at rodeos. New research published in BioMed Central’s open access journal BMC Genomics used ‘next-generation’ sequencing to map variation in the genome of a Quarter Horse mare. Analysis of genetic variants associated with specific traits showed that compared to a Thoroughbred the Quarter Horse’s genome was enriched for variants in genes involved in sensory perception, signal transduction and the immune system. Quarter Horses have been selectively bred to improve speed over short distances. However they also prone to some disorders such as hereditary equine regional dermal asthenia (HERDA) where their skin is fragile and tears easily. Researchers from Texas A&M University sequenced a Quarter Horse genome with the aim of finding what makes these horses so special. They looked at genetic variants, including single nucleotide polymorphisms (SNP), copy number variants (CNV), insertions and deletions (INDELs), as well as mutations associated with performance traits and diseases which are responsible for the makeup of these horses. By comparing the Quarter Horse’s sequence with that of a Thoroughbred, over three million of these variations were found. With the help of a human gene identification library, pathways, traits and diseases associated with the variations and mutations found in the horse were identified.

Dr Scott Dindot from Texas A&M University College of Veterinary medicine explained, “When we compared the genomic sequence of our mare to that of a Thoroughbred genome, we found that the Quarter Horse had more genetic variation — especially in genes involved in sensory perception, immunity, and cellular processes. When we looked for disease causing mutations and variants associated with performance traits we discovered that the Quarter Horse was heterozygous for a mutation in the cyclophilin B gene which is responsible for HERDA, and a SNP associated with chestnut coat color. The horse also had SNPs associated with racing endurance, originating in Thoroughbreds, which may explain the Quarter Horse’s speed and stamina.” The sequencing of horse genome has been of great benefit to equine breeders and veterinary medicine because of the possibilities of improving health and performance. This information can also be used to understand the theory underlying horse evolution. Recently mitochondrial sequencing of domestic horses and a Przewalski horse was able to show that most of the genetic variation between modern breeds was already present in ancestral stock. This new research, the first to use next-generation sequencing, has provided information which will be a useful resource in understanding the genetic basis behind horse breeds and disease.

Science Daily
March 6, 2012

Original web page at Science Daily

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Shuni virus as cause of neurologic disease in horses

To determine which agents cause neurologic disease in horses, we conducted reverse transcription PCR on isolates from of a horse with encephalitis and 111 other horses with acute disease. Shuni virus was found in 7 horses, 5 of which had neurologic signs. Testing for lesser known viruses should be considered for horses with unexplained illness. Several mosquito-borne alphaviruses, flaviviruses, and orthobunyaviruses, including West Nile, Rift Valley fever, and chikungunya viruses, with zoonotic potential have emerged from Africa to cause major outbreaks in previously unaffected areas. Horses are highly sensitive to some of these viruses and have been used as sentinels for the identification of arboviruses associated with neurologic disease in South Africa. During the seasonal occurrence of common vector-borne diseases such as African horse sickness and equine encephalosis, many horses have febrile, neurologic, and fatal infections for which the etiology remains undetermined.

We report a case in which a virus isolated in cell culture from the brain of a euthanized horse that had severe encephalitis was identified as Shuni virus (SHUV), a member of the family Bunyaviridae, genus Orthobunyavirus, serogroup Simbu. SHUV-specific primers were designed and used to perform reverse transcription PCRs (RT-PCRs) on specimens from an additional 111 horses with fever and nervous disease that had been screened for the more common pathogens over 18 months. The study was conducted in accordance with the recommendations of the Faculty of Health Sciences Ethics Committee of the University of Pretoria under protocols 129/2006 and H016-09. SHUV was first isolated in the 1960s from cattle and sheep in abattoirs (Cuilicoides spp. midges tested as part of arbovirus surveys and in 1 instance from a febrile child in Nigeria). Subsequently, the virus was isolated from pools of Culex theileri mosquitoes caught near Johannesburg and from cattle and a goat in KwaZulu-Natal Province, South Africa. In 1977, the virus was isolated from the brains of 2 horses that died of nervous disease, 1 in South Africa and 1 in Zimbabwe. Despite these data, no further investigations were undertaken to determine the role of the virus as a cause of neurologic disease in humans or animals. Identification of SHUV from a horse with severe neurologic signs prompted us to design specific Shuni virus primers and screen further cases of acute disease.

Over 18 months we identified 7 cases of SHUV infection, 5 of which were associated with neurologic signs. Our findings suggest that the role of SHUV as a pathogen may be underestimated and that it should be investigated routinely as a possible cause of unexplained nervous disease in humans and other animals in Africa. Most cases were identified in the autumn and winter months, which overlap with African horse sickeness, equine encephalosis, and West Nile virus outbreaks in South Africa, which have similar clinical signs. Such overlaps may contribute to the underrecognition of lesser known viruses, such as SHUV, because routine diagnostic investigation is limited to the more common viruses. The discovery of a co-infection with Middelburg virus in 1 of the horses implies that broad screening for arbovirus infections in unexplained illnesses is warranted, and consideration should be given to inclusion of generic RT-PCRs for alphaviruses, flaviviruses, orthobunyaviruses, and vesiculoviruses, in addition to African horse sickness and equine encephalosis viruses in future studies. Moreover, the inclusion of tests for immune response would improve the success rate for establishing diagnoses because viremia is fleeting in most arbovirus infections.

Emerging Infectious Diseases
February 21, 2012

Original web page at Emerging Infectious Diseases

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‘Speed gene’ in modern racehorses originated from British mare 300 years ago

Scientists have traced the origin of the ‘speed gene’ in Thoroughbred racehorses back to a single British mare that lived in the United Kingdom around 300 years ago, according to findings published today in the scientific journal Nature Communications. The origin of the ‘speed gene’ (C type myostatin gene variant) was revealed by analysing DNA from hundreds of horses, including DNA extracted from the skeletal remains of 12 celebrated Thoroughbred stallions born between 1764 and 1930. “Changes in racing since the foundation of the Thoroughbred have shaped the distribution of ‘speed gene’ types over time and in different racing regions,” explained Dr Emmeline Hill, the senior author of the study, and a genomics scientist at the School of Agriculture and Food Science, University College Dublin. “But we have been able to identify that the original ‘speed gene’ variant entered the Thoroughbred from a single founder, which was most likely a British mare about 300 years ago, when local British horse types were the preeminent racing horses, prior to the formal foundation of the Thoroughbred racehorse.”

The international scientific team led by scientists from University College Dublin (UCD), Equinome Ltd and the University of Cambridge, have traced all modern variants of the original ‘speed gene’ to the legendary Nearctic (1954-1973), and attribute the wider expansion of these variants to Northern Dancer (1961-1990), the son of Nearctic, and one of the most influential stallions of modern times. “Having first identified the ‘speed gene’ in 2010, we decided to see if we could trace the origin of the gene variant using population genetics coupled with pedigree analysis. We wanted to understand where speed in the Thoroughbred came from.,” said Dr Hill. Dr Hill is also a co-founder of Equinome, a UCD spin-out company headquartered at NovaUCD, which has developed The Equinome Speed Gene Test. This test is currently being used by the global bloodstock and racing industry to identify the optimum racing distance for individual Thoroughbred horses. “We traced the economically valuable gene variant by determining ‘speed gene’ type in almost 600 horses from 22 Eurasian and North American horse breeds, museum bone and tooth specimens from 12 legendary Thoroughbred stallions, 330 elite performing modern Thoroughbreds from 3 continents, 40 donkeys and two zebras,” added Dr Hill.

According to co-author Dr Mim Bower from the University of Cambridge, UK, “The findings point to a British mare as the most likely single founder of the original ‘speed gene’ because one of the lines of evidence from the research demonstrated that the prize stallions of the 17th and 18th centuries had two copies of the T type speed gene variant (T:T) which is linked to greater stamina.” “At this time in the history of horse racing, races were between two horses competed over multiple heats, at distances of between two to four miles, and repeated until a horse had won the event twice or ‘distanced’ the opponent. Horses did not race until they were five or six years old, and then only two or three times in their lives. This is consistent with these horses being T:T types.,” said Dr Bower. An increased premium on speed and precocity developed as two-year-old races became popular during the last century, and in many regions of the world, these preferences remain to this day. Dr Hill explained, “For example, in Australia, the myostatin ‘speed gene’ type (C:C), which is best suited to fast, short-distance, sprint races, is more common and there is a market driven demand for horses with at least one copy of the C type gene variant.” “This just goes to show the power breeders have to shape the genetic make-up of their horses. Decisions regarding the race pattern in each racing jurisdiction and the commercial demand for certain types will also rapidly influence the genetic make-up of the population.”

To identify where the C type gene variant originated, the researchers analysed DNA samples from more than 20 horse breeds that included representatives of local British and Irish horses, from where female Thoroughbred lineages derive, and exotic eastern populations from where male Thoroughbred lineages derive. The study identified the Shetland breed as having the highest frequency of the C type gene variant. The Shetland represents local British horse types, which were the preeminent racing horses prior to the formal foundation of the Thoroughbred. By comparing the diversity of the chromosomes around the C and T type gene variants researchers found only a single C type compared to 11 different T type gene variants, meaning that the ‘speed gene’ entered the Thoroughbred just once. “The results show that the ‘speed gene’ entered the Thoroughbred from a single founder, which was most likely a British mare about 300 years ago when local British horse types were the preeminent racing horses, prior to the formal foundation of the Thoroughbred racehorse.,” said Dr Hill.

Science Daily
February 7, 2012

Original web page at Science Daily

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Experimental infection of horses with Hendra Virus

Hendra virus (HeV) is a highly pathogenic zoonotic paramyxovirus harbored by Australian flying foxes with sporadic spillovers directly to horses. Although the mode and critical control points of HeV spillover to horses from flying foxes, and the risk for transmission from infected horses to other horses and humans, are poorly understood, we successfully established systemic HeV disease in 3 horses exposed to Hendra virus by the oronasal route, a plausible route for natural infection. In 2 of the 3 animals, HeV RNA was detected continually in nasal swabs from as early as 2 days postexposure, indicating that systemic spread of the virus may be preceded by local viral replication in the nasal cavity or nasopharynx. Our data suggest that a critical factor for reducing HeV exposure risk to humans includes early consideration of HeV in the differential diagnosis and institution of appropriate infection control procedures.

Hendra virus (HeV) is a zoonotic paramyxovirus harbored by Australian mainland flying foxes, from which it is believed to be transmitted directly to horses. In horses, HeV causes a severe, often fatal, febrile illness associated with respiratory and neurologic signs. Since its emergence in Queensland, Australia, in 1994, HeV infection of horses has regularly recurred. Of the 25 equine outbreaks, 5 have extended to involve infection of humans; of the 7 known human case-patients, 4 have died. Human infection has typically occurred after close contact with infected horses, usually horses in the terminal stages of disease or at postmortem examination, except for 1 person for whom epidemiologic findings suggested the most likely exposure to an infected horse occurred during incubation. Currently, HeV is an unmanaged emerging infectious disease. Since the serious zoonotic potential of HeV was confirmed, clinical and laboratory evaluation of disease horses from outbreaks has been limited. In particular, the relationship between the onset of clinical signs and duration of viral shedding has not been determined, and the understandably few equine experimental infection studies conducted in the mid-1990s yielded limited data that could guide effective management of the exposure risk to humans.

Emerging Infectious Diseases
November 29, 2011

Original web page at Emerging Infectious Diseases

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Ancient DNA provides new insights into cave paintings of horses

An international team of researchers has used ancient DNA to shed new light on the realism of horses depicted in prehistoric cave paintings. The team, which includes researchers from the University of York, has found that all the colour variations seen in Paleolithic cave paintings — including distinctive ‘leopard’ spotting — existed in pre-domestic horse populations, lending weight to the argument that the artists were reflecting their natural environment. The study, published in Proceedings of the National Academy of Sciences (PNAS), is also the first to produce evidence for white spotted phenotypes in pre-domestic horses. Previous ancient DNA studies have only produced evidence for bay and black horses. Archaeologists have long debated whether works of art from the Paleolithic period, particularly cave paintings, are reflections of the natural environment or have deeper abstract or symbolic meanings. This is particularly true of the cave painting “The Dappled Horses of Pech-Merle” in France, which dates back more than 25,000 years and clearly depicts white horses with dark spots. The dappled horses’ spotted coat pattern bears a strong resemblance to a pattern known as ‘leopard’ in modern horses. However, as some researchers believed a spotted coat phenotype unlikely at this time, pre-historians have often argued for more complex explanations, suggesting the spotted pattern was in some way symbolic or abstract.

Researchers from the UK, Germany, USA, Spain, Russia and Mexico genotyped and analysed nine coat-colour loci in 31 pre-domestic horses dating back as far as 35,000 years ago from Siberia, Eastern and Western Europe and the Iberian Peninsula. This involved analysing bones and teeth specimens from 15 locations. They found that four Pleistocene and two Copper Age samples from Western and Eastern Europe shared a gene associated with leopard spotting, providing the first evidence that spotted horses existed at this time. In addition, 18 horses had a bay coat colour and seven were black, meaning that all colour phenotypes distinguishable in cave paintings — bay, black and spotted — existed in pre-domestic horse populations. Professor Michi Hofreiter, from the Department of Biology at the University of York, said: “Our results suggest that, at least for wild horses, Paleolithic cave paintings, including the remarkable depictions of spotted horses, were closely rooted in the real-life appearance of animals. “While previous DNA studies have produced evidence for bay and black horses, our study has demonstrated that the leopard complex spotting phenotype was also already present in ancient horses and was accurately depicted by their human contemporaries nearly 25,000 years ago.

“Our findings lend support to hypotheses that argue that cave paintings constitute reflections of the natural environment of humans at the time and may contain less of a symbolic or transcendental connotation than often assumed.” The data and laboratory work were led by Dr Melanie Pruvost, from the Department of Evolutionary Genetics at the Leibniz Institute for Zoo and Wildlife Research and the Department of Natural Sciences at the German Archaeological Institute, both in Berlin. The results were replicated in laboratories at the University of York. Dr Pruvost said: “We are just starting to have the genetic tools to access the appearance of past animals and there are still a lot of question marks and phenotypes for which the genetic process has not yet been described. However, we can already see that this kind of study will greatly improve our knowledge about the past. Knowing that leopard spotting horses were present during the Pleistocene in Europe provides new arguments or insights for archaeologists to interpret cave arts.” Dr Arne Ludwig, from the Leibniz Institute for Zoo and Wildlife Research in Berlin, added: “Although taken as a whole, images of horses are often quite rudimentary in their execution, some detailed representations, from both Western Europe and the Ural mountains, are realistic enough to at least potentially represent the actual appearance of the animals when alive. “In these cases, attributes of coat colours may also have been depicted with deliberate naturalism, emphasizing colours or patterns that characterised contemporary horses.”

Exact numbers of Upper Paleolithic sites with animal depictions are uncertain because of ongoing debates about the taxonomic identification of some images and dating. However, art of this period has been identified in at least 40 sites in the Dordogne-Périgord region, a similar number in coastal Cantabria and around a dozen sites in both the Ardèche and Ariège regions. Where animal species can be confidently identified, horses are depicted at the majority of these sites. Professor Terry O’Connor from the University of York’s Department of Archaeology was involved in the interpretation of the results. He said: “Representations of animals from the Paleolithic period have the potential to provide first-hand insights into the physical environment that humans encountered thousands of years ago. However, the motivation behind, and therefore the degree of realism in these depictions is hotly debated. “The depictions of horses at Pech-Merle in particular have generated a great deal of debate. The spotted horses are featured in a frieze which includes hand outlines and abstract patterns of spots. The juxtaposition of elements has raised the question of whether the spotted pattern is in some way symbolic or abstract, especially since many researchers considered a spotted coat phenotype unlikely for Paleolithic horses. “However, our research removes the need for any symbolic explanation of the horses. People drew what they saw, and that gives us greater confidence in understanding Paleolithic depictions of other species as naturalistic illustrations.”

Leopard complex spotting in modern horses is characterised by white spotting patterns that range from horses having a few white spots on the rump to horses that are almost completely white. The white area of these horses can also have pigmented oval spots known as ‘leopard spots’. Dr. Monika Reissmann, from Humboldt University’s Department for Crop and Animal Sciences, explained: “This phenotype was in great demand during the Baroque Age. But in the following centuries the leopard complex phenotype went out of fashion and became very rare. Today leopard complex is a popular phenotype in several horse breeds including Knabstrupper, Appaloosa and Noriker and breeding efforts have intensified again because there is a growing interest in the restoration of these horses.” The fact that four out of 10 of the Western European horses from the Pleistocene had a genotype indicative of the leopard complex phenotype, suggests that this phenotype was not rare in Western Europe during this period. However, bay seems to have been the most common colour phenotype in pre-domestic times with 18 out of the 31 samples having bay genotypes. This is also the most commonly painted phenotype in the Paeolithic period.

Science Daily
November 29, 2011

Original web page at Science Daily

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Light dependency underlies beneficial jetlag in racehorses

A new study has shown that racehorses are extremely sensitive to changes in daily light and, contrary to humans, can adapt very quickly to sudden shifts in the 24-hour light-dark cycle, such as those resulting from a transmeridian flight, with unexpected benefits on their physical performance. The research led by academics in the University of Bristol’s Faculty of Medical and Veterinary Sciences is published in the Journal of Neuroendocrinology. This is the first study of its kind to investigate the effects of jetlag on the physiology and performance of racehorses under tightly controlled experimental conditions. Horses are the only athletes, apart from humans, regularly flown across time zones for athletic competitions. Dr Domingo Tortonese, Senior Lecturer in Anatomy in the School of Veterinary Sciences, who led the study, said: “We tested the hypothesis that abrupt alterations in the 24-hour light-dark cycle, such as those associated with the crossing of time-zones, would alter the molecular clockwork and neuroendocrine systems of racehorses with detrimental consequences on their athletic performance. In humans, air travel-associated sudden changes in the 24-hour light-dark cycle disrupt biological rhythms with negative effects on cognitive and physical performance. Indeed, jetlag has important implications for athletes who travel across time zones for competitive sporting events, particularly after an easterly flight.

“Our study shows that racehorses are different from humans in that they rely on light cues for their daily rhythms of activity, rather than for the synchronisation of an endogenously generated rhythm to the 24-hour light-dark cycle. This light dependency underlies a rapid process of adaptation with critical scientific implications and unexpected practical benefits.” Thoroughbred horses with previous race training were housed in light-controlled rooms and put through a fitness program of daily sessions of exercise on a high–speed treadmill at variable times of the day for three months. They then experienced a shift in the 24-hour light-dark cycle that mimicked an easterly flight across seven time zones. The 24-hour patterns of four clock genes, together with neuroendocrine systems involved in a variety of functions, including time measurement, homeostasis and the response to stress, were investigated before and after the shift. The aerobic and anaerobic capacities were measured by standardised performance tests. Locomotor activity was also assessed continuously, under photoperiodic conditions and in the absence of light cues (constant darkness), to determine the expression and robustness of a 24-hour rest-activity cycle.

The speed of re-adaptation to a new light-dark cycle was also investigated. Contrary to the prediction based on human and rodent data, the results show that whereas horses are extremely sensitive to sudden changes in the 24-hour light-dark cycle, they can adapt very quickly to a phase shift. Importantly, this rapid adaptation is not accompanied by an increase in the level of stress, but by alterations in endocrine systems that favour an enhancement of the horse’s physical capacity during the process. The improvement in athletic performance following experimental jetlag resulted in the animals being able to run at full gallop for an additional 25 seconds before reaching fatigue. This differs from humans who show a slow adjustment, particularly after an eastbound flight, with detrimental consequences on performance. The difference between the two species can be attributed to the powerful masking effect of light on the horse’s daily locomotor activity, which, together with the absence of a robust sleep-wake cycle, can be a part of a mechanism of adaptation to sudden changes in the environment. The results of this study have important practical implications, since equine athletes do not need to travel to be subjected to changes in daily light, and its beneficial consequences could help to reduce the level of injury in competitions.

EurekAlert! Medicine
November 1, 2011

Original web page at EurekAlert! Medicine

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Antibody treatment protects monkeys from Hendra virus disease

A human antibody given to monkeys infected with the deadly Hendra virus completely protected them from disease, according to a study published by National Institutes of Health (NIH) scientists and their collaborators. Hendra and the closely related Nipah virus, both rare viruses that are part of the NIH biodefense research program, target the lungs and brain and have human case fatality rates of 60 percent and more than 75 percent, respectively. These diseases in monkeys mirror what happens in humans, and the study results are cause for hope that the antibody, named m102.4, ultimately may be developed into a possible treatment for people who become infected with these viruses. In May 2010, shortly after the NIH study in monkeys successfully concluded, Australian health officials requested m102.4 for emergency use in a woman and her 12-year-old daughter. They had been exposed to Hendra virus from an ill horse that ultimately was euthanized. Both the woman and child survived and showed no side effects from the treatment. “This is an important research advance that illustrates how scientific discoveries emerge through a steady stepwise process, and how our investment in research on countermeasures for biodefense and emerging infectious diseases can help global preparedness efforts,” said Anthony S. Fauci, M.D., director of the NIH’s National Institute of Allergy and Infectious Diseases (NIAID).

Hendra virus emerged in 1994 in Australia and primarily affects horses, which can spread the disease to humans. No person-to-person transmission of Hendra has been reported. Nipah virus emerged in 1998 in Malaysia, and also has been found in Bangladesh and India. Nipah appears to infect humans more easily than Hendra and can be transmitted from person to person. The NIAID-supported study, which appears online in Science Translational Medicine, involved infecting 14 African green monkeys with a lethal dose of Hendra virus. Twelve of the monkeys then received two treatments with m102.4, one either at 10, 24, or 72 hours after being infected, and another 48 hours later. All 12 monkeys treated with the antibody survived. The two untreated control monkeys died eight days after being infected. The findings are the result of a series of studies carried out by different research laboratories. A group from NIH’s National Cancer Institute and the Uniformed Services University of the Health Sciences (USUHS) discovered m102.4 in 2006 and developed the antibody for use in laboratory research. USUHS and Australian collaborators then developed an animal study model of m102.4 in ferrets infected with Nipah virus; the University of Texas Medical Branch and USUHS developed a monkey study model of Hendra and Nipah infection; and together with investigators from Boston University and NIAID’s Rocky Mountain Laboratories (RML) designed and carried out the antibody trial in biosafety level-4 (BSL-4) laboratory space at RML. Because the Hendra and Nipah viruses are so deadly and there is no licensed vaccine or treatment for either of them, both viruses must be studied in maximum-containment BSL-4 laboratories.

The World Health Organization reports 475 human cases of Nipah through 2008, with 251 deaths. Through the same period, there have been seven human Hendra cases with four fatalities. There also have been many horse fatalities. In their study, the scientists cite a handful of other outbreaks of Hendra virus in horses since 2008. Since June 2011, there have been 18 outbreaks in Australia, primarily in Queensland and New South Wales, with the latest reported Oct. 10. Both viruses are spread by fruit bats, commonly known as flying foxes, which are reservoirs for these viruses. The fruit bats, which are resistant to the diseases, are found primarily in Australia but have been found as far west as Africa, north to India and Pakistan, and east to the Philippines.

Science Daily
November 1, 2011

Original web page at Science Daily

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Tick responsible for equine piroplasmosis outbreak identified

The cayenne tick has been identified as one of the vectors of equine piroplasmosis in horses in a 2009 Texas outbreak, according to U.S. Department of Agriculture (USDA) scientists. The United States has been considered free from the disease since 1978, but sporadic cases have occurred in recent years. In October 2009, in Kleberg County, Texas, a mare was presented for veterinary care with clinical signs of infection, including poor appetite and weight loss. Subsequent investigation and testing confirmed the original case and identified more than 290 additional infected animals on the ranch. Research leader Donald Knowles, entomologist Glen Scoles and veterinary medical officer Massaro Ueti with the Agricultural Research Service (ARS) Animal Disease Research Unit, in Pullman, Wash., and collaborator Robert Mealey with Washington State University in Pullman have been working on the project with USDA’s Animal and Plant Health Inspection Service (APHIS) and the Texas Animal Health Commission (TAHC).

ARS is USDA’s principal intramural scientific research agency, and the research supports the USDA priority of promoting international food security. The researchers’ goal was to assess and prevent the spread of the Texas outbreak, which could have serious international trade implications if it is found to have spread beyond the ranch where the outbreak occurred. Part of their initiative was to identify the tick species responsible for the new outbreak. Only two U.S. tick species — Dermacentor variabilis and Rhipicephalus (Boophilus) microplus — had previously been shown experimentally to be vectors of Theileria equi, the microbe that causes equine piroplasmosis, according to Scoles. The cayenne tick, Amblyomma cajennense, had not previously been shown to be a competent vector. Adult cayenne ticks were collected from positive horses on the outbreak ranch and allowed to re-attach and feed on a noninfected horse. Scoles led the study showing these ticks successfully transmitted T. equi. The results will be published in the October issue of Emerging Infectious Diseases. Knowles, Ueti and Mealey are treating some of the South Texas horses with imidocarb dipropionate. Tests conducted thus far by the team have been promising and trials are ongoing.

Science Daily
October 18, 2011

Original web page at Science Daily

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Endangered horse has ancient origins and high genetic diversity

An endangered species of horse — known as Przewalski’s horse — is much more distantly related to the domestic horse than researchers had previously hypothesized, reports a team of investigators led by Kateryna Makova, a Penn State University associate professor of biology. The scientists tested the portion of the genome passed exclusively from mother to offspring — the mitochondrial DNA — of four Przewalski’s horse lineages and compared the data to DNA from the domestic horse (Equus caballus). They concluded that, although previous scientists had assumed that Przewalski’s horse and the domestic horse had diverged around the time that horses were domesticated — about 6,000 to 10,000 years ago — the real time of the two species’ divergence from one another is much more ancient. The data gleaned from the study also suggest that present-day Przewalski’s horses have a much more diverse gene pool than previously hypothesized. The new study’s findings could be used to inform conservation efforts to save the endangered horse species, of which only 2,000 individuals remain in parts of China and Mongolia, and in wildlife reserves in California and the Ukraine. The paper will be published in the journal Genome Biology and Evolution.

Przewalski’s horse — a stocky, short-maned species named after a Russian explorer who first encountered the animal in the wild — became endangered during the middle of the last century when the species experienced a population bottleneck — an evolutionary event in which many or most members of a population or a species die. “Sadly, this bottleneck was the result of human activity,” Makova explained. “Przewalski’s horses were hunted down for food, and their natural habitat, the steppes, were converted into farm land so the horses basically had nowhere to live and breed. By the late 1950s, only 12 individual horses remained.” Makova said that because conservationists have made noble efforts to rescue this dwindling population, the present-day population has grown to 2,000. In a study that had never been attempted by previous scientists, Makova and her team analyzed the complete mitochondrial genomes from four female lineages that currently survive within the Przewalski’s horse population. They first determined that the mitochondrial genomes of two of the maternal lineages actually were identical, thus narrowing the genetic pool to three maternal lineages. Then, they tested their data against the prevailing hypotheses about the genetic history of Przewalski’s horse. According to one hypothesis, Przewalski’s horse evolved first, with the domestic horse later evolving as a derivative species. According to another hypothesis, the genetic story is the opposite: the direct ancestors of the domestic horse were first on the evolutionary scene, with Przewalski’s horse evolving and forming a new species later. According to the former hypothesis, the divergence of the two species had to have occurred around the time of horse domestication — about 6,000 to 10,000 years ago.

“My team discovered that neither scenario is likely,” Makova said. “Instead, our data suggest that Przewalski’s horse and the domestic horse are much more distantly related. In fact, they probably shared a common ancestor as far back as 160,000 years ago, long before horse domestication. This is a major shift in our understanding of the history of Przewalski’s horse.” To bolster their conclusions, the team also sequenced a portion of the Przewalski’s horse’s nuclear DNA — the part of the genome passed to offspring from parents of both sexes. In addition, they sequenced a portion of the genome of a third species known as the Somali wild ass, the wild progenitor of donkeys. Makova explained that adding this information allowed her team to “calibrate the molecular clock of horse evolution,” thus narrowing the window of time for sub-species divergence and confirming her team’s suspicions that horse domestication and the emergence of Przewalski’s horse were two very distant and independent events. Makova added that, although the two species diverged well over 100,000 years ago, they have interbred periodically since then. “Also fortunate is the fact that conservationists in the second half of the 20th century realized how grave the situation was for the Przewalski’s horse. They not only began new breeding efforts and built wildlife reserves in California and the Ukraine, but they also made sure to avoid inbreeding among close relatives,” Makova said. “For this reason, the present-day population has managed to remain healthy by retaining substantial genetic diversity.”

Makova and her team hope that their findings will help guide future conservation efforts for the endangered horse species. “The idea is to gradually reintroduce Przewalski’s horse into the wild,” Makova said. “For example, now that we have a more thorough understanding of the different maternal lineages, we can diversify the animal’s gene pool even more. This will be a way to ensure that members of wild species suffer as few recessive diseases as possible and have the best opportunity to flourish once they are introduced into the appropriate habitat.” In addition, the researchers hope to further horse-evolution studies by sequencing the genomes of additional breeds of domestic horses, and, eventually, by sequencing the complete genome of Przewalski’s horse. “More genetic data means a more precise evolutionary clock,” Makova explained. “The more we know, the more we can adjust the time frame for when Przewalski’s horse and other horses diverged from their common ancestor.” Makova added that she and her team also would like to identify the genes that code for the physical differences between Przewalski’s horse and the domestic horse. “It’s always been a curious question why Przewalski’s horse is so much shorter and stockier in stature than the domestic horse, and also why Przewalski’s horse has a shorter, thicker mane,” Makova said. “A deeper genetic analysis and subsequent experiments could reveal the very genes that determine differences in appearance between the two species.”

PhysOrg.com
September 20, 2011

Original web page at PhysOrg.com

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Ancient wild horses help unlock past

An international team of researchers has used ancient DNA to produce compelling evidence that the lack of genetic diversity in modern stallions is the result of the domestication process. The team, which was led by Professor Michi Hofreiter from the University of York, UK, has carried out the first study on Y chromosomal DNA sequences from extinct ancient wild horses and found an abundance of diversity. The results, which are published in Nature Communications, suggest the almost complete absence of genetic diversity in modern male horses is not based on properties intrinsic to wild horses, but on the domestication process itself. Professor Hofreiter said: “Unlike modern female domestic horses where there is plenty of diversity, genetic diversity in male horses is practically zero. “One hypothesis to explain this suggests modern horses have little Y chromosome diversity because the wild horses from which they were domesticated were also not diverse, due in part to the harem mating system in horses, implying skewed reproductive success of males. Our results reject this hypothesis as the Y chromosome diversity in ancient wild horses is high. Instead our results suggest that the lack of genetic diversity in modern horses is a direct consequence of the domestication process itself.”

The Y chromosome is a valuable tool in population genetics, providing a means of directly assessing evolutionary processes that only affect the paternal lineage. So far mitochondrial DNA studies have failed to discover the origin of domestic horses. However, these new Y chromosomal markers now open the possibility of solving this issue in detail. As part of the study, researchers sequenced Y chromosomal DNA from eight ancient wild horses dating back from around 15,000 to more than 47,000 years and a 2,800-year-old domesticated horse. The results were compared to DNA sequences from Przewalski horses — the only surviving wild horse population — and 52 domestic horses, representing 15 modern breeds, which had been sequenced previously. Domestication of horses dates back approximately 5,500 years. DNA from the skeletal remains of a 2,800-year-old domesticated stallion from Siberia showed that in contrast to modern horses, Y chromosomal diversity still existed several thousand years after the initial domestication event for horses. Professor Hofreiter said: “This suggests some level of Y chromosomal diversity still existed in domestic horses several thousand years after domestication, although the lineage identified was closely related to the modern domestic lineage.” The study was carried out in Germany by Sebastian Lippold, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The results were then independently replicated at the Centre for GeoGenetics at Copenhagen University, Denmark.

Sebastian Lippold said: “Working on ancient Y chromosomal DNA was especially challenging but the only opportunity to investigate Y chromosomal diversity in wild horses. For now we have a first idea of ancestral diversity and therefore a better impression of how much diversity has been lost. Basically this was an important first step and points to the potential the Y chromosomal marker could have in order to further investigate domestication history in horses.” Beth Shapiro, an Assistant Professor in the Department of Biology at the Pennsylvania State University, USA, carried out the analysis and interpretation. She said: “Most ancient DNA research until now has focused on a different part of the genome — the mitochondrion — which is much more abundant in cells and therefore much easier to work with when the DNA is degraded. This has been a serious limitation in ancient DNA research, because we generally only have a good idea what happened along the maternal line. Here, we’ve been able to look at what happened along the paternal lineage, and, probably unsurprisingly, we see something different going on in males than in females. “This is exciting stuff, and means we can start getting a much better picture of how events like domestication and climate change have shaped the diversity of organisms alive today.” Researchers had found that Przewalski’s horse displays DNA haplotypes not present in modern domestic horses, suggesting they are not ancestral to modern domestic horses. However, while the Y chromosome data supported historic isolation, it also suggests a close evolutionary relationship between the domestic horse and the Przewalski’s horse, since the Przewalski Y chromosomal haplotype is more similar to the two domestic ones than any of the ancient wild horse haplotypes.

Science Daily
September 6, 2011

Original web page at Science Daily

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Horse blind date could lead to loss of foal

Fetal loss is a common phenomenon in domestic horses after away-mating, according to Luděk Bartoš and colleagues, from the Institute of Animal Science in the Czech Republic. When mares return home after mating with a foreign stallion, they either engage in promiscuous mating with the home males to confuse paternity, or, failing that, the mares abort the foal to avoid the likely future infanticide by the dominant home male. The study is published online in the Springer journal Behavioral Ecology and Sociobiology. In the Czech Republic, it is common practice for domestic horse mares to be removed from their home environment and transported elsewhere for mating. After conceiving, they are returned back into their home environments and social groups, often with familiar males. The authors looked at whether there was a link between the common practice of away-mating and fetal loss. They distributed a questionnaire on reproduction to private horse owners in the Czech Republic through an equine internet server. They compared the frequency of abortion between mares which had conceived with a home stallion and those mated with a foreign stallion. They then looked at the sexual behavior of mares returning from away-mating.

Mares mated with a foreign stallion aborted in 31 percent of cases while none of the mares mated within the home stable aborted. Furthermore, mares were more likely to have disrupted pregnancies when home males were in adjacent enclosures. Bartoš and colleagues’ results uncover a new phenomenon in domestic horses: a female counter-strategy to male infanticide. It appears that domestic mares choose not to raise foals fathered by stallions outside the home herd. If the dominant home male is not the father, he may subsequently attempt infanticide. Two things happen as a result. Either mares manipulate the males’ paternity assessment by promiscuous mating with home males. Alternatively, if the mares are physically unable to have sexual activity with home males, i.e. they are in separate enclosures, they are seven times more likely to abort the fetus, to prevent the waste of energy in producing offspring likely to be lost. The authors conclude: “The phenomenon shown in this study may explain the high incidence of domestic horse fetal loss. The regular practice of transporting the mare for mating or artificial insemination with a foreign stallion, and then bringing her back to an environment with home males, is probably one of the main causes of such high percentages of pregnancy disruption in domestic horses.”

Science Daily
July 12, 2011

Original web page at Science Daily

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Vaccine protects from deadly Hendra virus

CSIRO scientists have shown that a new experimental vaccine helps to protect horses against the deadly Hendra virus. Deborah Middleton from CSIRO’s Australian Animal Health Laboratory (AAHL) announced the successful progress to develop the vaccine at the Australian Veterinary Association conference in Adelaide on May 17, 2011. “Our trials so far have shown that the vaccine prevents the infection of horses with Hendra virus,” Dr Middleton said. Stopping the disease in horses could also help protect people from the disease. “A horse vaccine is crucial to breaking the cycle of Hendra virus transmission from flying foxes to horses and then to people, as it prevents both the horse developing the disease and passing it on,” Dr Middleton said. Hendra virus first appeared in 1994 and five of the 14 known outbreaks have spread to people. The virus has killed four of the seven people infected. Depending on further development, field trials and registration the vaccine may be available as early as 2012. Dr Barry Smyth, President of the Australian Veterinary Association, said that the news on the vaccine will be welcomed by both vets and horse owners.

“It’s important that veterinarians and horse owners continue with precautions that reduce the risk of spreading the virus and that they report suspected cases immediately,” Dr Smyth said. Recent work on evaluating the vaccine was jointly funded by the CSIRO, the Australian Government Department of Agriculture, Fisheries and Forestry and the Queensland Government Department of Employment, Economic Development and Innovation. The development of the vaccine goes back more than ten years to shortly after CSIRO scientists first isolated the virus following the first outbreak of the disease in Hendra, Queensland. Development and source of the vaccine is the result of a close collaboration with Dr Christopher Broder of the Uniformed Services University of the Health Sciences (the US federal health sciences university) supported by the US National Institutes of Health, but the high bio-containment facility at AAHL was essential for evaluating its beneficial effects. “Our bio-security facility at AAHL is the only laboratory in the world where this work could have been done. It has been slow, painstaking and high-risk work and the credit is due to many people who’ve worked on this since 1994,” Dr Middleton said.

Science Daily
May 31, 2011

Original web page at Science Daily

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Treating newborn horses: A unique form of pediatrics

Like any other newborn, the neonatal horse can be a challenging patient. Its immune system is still under construction, its blood chemistry can vary wildly, and — like most infants — it wants to stay close to mom. These factors are magnified in the critically ill foal, said Pamela Wilkins, a professor of equine internal medicine and emergency/critical care at the University of Illinois and the author of a new paper on equine neonatal intensive care. The paper, in Clinical Laboratory Medicine, offers guidance to the large-animal veterinarian and demonstrates the very real challenges of the job. Sickness can play havoc with a foal’s blood chemistry, Wilkins said. Teasing out the causes of these changes requires that the veterinarian first understand what is normal in a newborn horse, and then how it can go wrong. To help address current gaps in knowledge, Wilkins regularly conducts blood tests or other tests, such as X-rays and CT scans, on healthy foals to determine how their body chemistry or physiology differ from that of an adult horse — or from that of a sick foal.

“Roughly 3 to 7 percent of newborn foals are going to have some kind of significant health issue in the first month of life,” Wilkins said. “And because our patients can’t talk to us, we have to figure out what’s wrong with them based on physical examination and testing and histories given by their owners.” The paper also offers guidance in the use of portable “point of care” devices to measure and monitor a sick foal’s changing health status. Such tools can offer immediate results in the field and cut costs associated with care. But the practitioner needs to know how use each device and interpret the results, Wilkins said. “For example, foals with severe infections can have a very, very low or a very high glucose level,” she said. Low blood glucose could be the result of the foal not taking in enough nutrients from its mother. Or the animal may not be able to make use of the glucose that is already stored as glycogen in its body. It’s the practitioner’s job to find out what’s going on, she said. To do that, veterinarians must understand the normal fluctuations in levels of glucose and other “biomarkers” of health or disease, Wilkins said.

“Blood glucose levels are going to be different between the normal, healthy adult horse and the healthy foal,” she said. “And they’re going to be different at different stages of the foal’s life.” Hormones, immune cells, red blood cells, protein levels, enzymes and electrolytes all vary between the adult and the infant horse, Wilkins said. And many of these markers change as the foal matures and grows. The challenges of treating a sick foal doesn’t end there, she said. A horse, even a foal, is a big, precocious animal. “Horses are a prey species, so they have to be able to get on their feet and run pretty quickly after birth,” she said. “The older and slower I get, the harder it is to approach them. You spend a lot of time on your knees dealing with them, and they can kick. I get bruises all over my body during foaling season and I have no idea where they’re from because I’m focused on what I’m doing.” Add a very protective mother to the equation, and the task gets even trickier. “The mom needs to be there,” Wilkins said. “She gets really upset if she’s not.” So when a foal comes into the hospital for critical care, the mother comes too. And like any mother with a sick baby, she hovers.

“Figuring out a way to keep mom from pulling the IV lines out and getting upset when you’re between her and the baby, that takes some doing,” Wilkins said. “The mothers don’t sleep; they don’t lie down; they don’t rest. They’re on their feet with their heads hanging over their babies most of the time. So it’s tough for them.” If a foal needs surgery, the medical staff will sedate the mom until the foal is back at her side. Wilkins’ patients may be the progeny of racehorses or performance horses, but many are also just people’s pets, she said. The cost of care can be high, so owners with a strong economic or emotional incentive are most likely to bring a critically ill foal to the hospital. Despite the many challenges, Wilkins loves the work. “Foals are just wonderful, wonderful creatures,” she said. “I can’t imagine working with anything else in my life.”

Science Daily
April 19, 2011

Original web page at Science Daily

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Fossils of horse teeth indicate ‘You are what you eat’

Fossil records verify a long-standing theory that horses evolved through natural selection, according to groundbreaking research by two anatomy professors at New York College of Osteopathic Medicine (NYCOM) of New York Institute of Technology. Working with colleagues from Massachusetts and Spain, Matthew Mihlbachler, Ph.D., and Nikos Solounias, Ph.D. arrived at the conclusion after examining the teeth of 6,500 fossil horses representing 222 different populations of more than 70 extinct horse species. The records, spanning the past 55 million years, indicate a “critical” lag time between the evolution of horse teeth and dietary changes resulting from climate change. The breakthrough findings were published in the March 4 issue of the journal Science.

“One of the advantages of studying extinct creatures like prehistoric horses is we can look at how animals responded to their environments over millions of years — something that biologists who study living species cannot do,” Mihlbachler said, adding that the biggest surprise of the study was that while some of the extinct populations they examined had extremely abrasive diets, much of the time, it seemed horses had it surprisingly easy. This suggests that “strong natural selection” for different types of teeth only happened occasionally during brief intervals in horse history. Solounias helped develop a methodology known as dental mesowear analysis to reconstruct the diets of extinct species by measuring food-related wear and tear on fossil teeth. He and Mihlbachler used the process to investigate wear patterns on the molars of thousands of fossil horses. They later analyzed their data alongside records of North American climate changes that would have shifted the animals’ diets from rainforest fruits and woody, leafy vegetation to the more abrasive diets found in grasslands.

“Lag time in the evolution of horse teeth in comparison to dietary changes is critical,” Mihlbachler explained. “We found that evolutionary changes in tooth anatomy lag behind the dietary changes by a million years or more.” While paleontologists have long held horses as classic examples of evolution through natural selection, the theory has been difficult to test because the majority of horse species are extinct. However, Mihlbachler and Solounias’ observation that dental changes in horses follow their dietary changes is consistent with evolution due to adaptation. “‘You are what you eat’: we hear this all the time, but now we know it is true,” explained Thomas Scandalis, Dean of NYCOM. “This study shows that the evolutionary path of horses as we know them today was affected by the food available to their prehistoric ancestors.” The duo’s research shows that not only has the number of horse species been greatly reduced in the past few million years, but also that the diets of horses have been narrowly restricted. “Living horses are anything but typical examples of the dietary ecology of this once great group of mammals,” Solounias said.

Science Daily
March 22, 2011

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Scientists generate pluripotent stem cells from horses

In a world first, pluripotent stem cells have been generated from horses by a team of researchers led by Dr. Andras Nagy at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital and Dr. Lawrence Smith at the University of Montreal’s Faculty of Veterinary Science. The findings will help enable new stem-cell based regenerative therapies in veterinary medicine, and because horses’ muscle and tendon systems are similar to our own, aid the development of preclinical models leading to human applications. The study was published in the February 28 issue of the leading journal Stem Cell Reviews and Reports. These induced pluripotent stem (iPS) cells can develop into most other cell types and are a source of great hope for use in regenerative medicine and the development of new drugs to prevent and treat various illnesses. One aspect of regenerative medicine is the process of creating living, functional tissues to repair or replace tissue or organ function lost due to damage or disease. “To date, iPS cells have been established from several species, but our study is the first to report the derivation of these changeable cells from horses,” Dr. Smith explained.

The research represents a breakthrough for both human and animal health alike. “Equine iPS cells bring new therapeutic potential to the veterinary field, and open up the opportunity to validate stem-cell based therapies before clinical studies in humans,” Dr. Nagy said. “As well, stem-cell based studies using the horse as a model more closely replicate human illnesses, when compared with studies in mice.” After two months of reprogramming equine somatic cells, the resulting iPS cell lines expressed hallmark markers of pluripotency, contained a correct set of horse chromosomes, and were able to form a full spectrum of cell types and tissues fulfilling the criteria of pluripotency. The term pluripotency refers to the ability of a stem cell to become any of the vast number of different cell types found in the body. “This means that the cell lines passed all the tests available to us for determining if they truly are what we think they are: pluripotent and a good source for future regenerative applications,” said Kristina Nagy, research associate in the Nagy laboratory and lead author of the study.

“The horse is an excellent model for a range of human degenerative diseases, especially those involving joints, bones, tendons and ligaments, such as arthritis,” said Dr. Sheila Laverty, a professor in the Faculty of Veterinary Medicine at the University of Montreal. “Bone fracture, as well as damaged cartilage, tendons and ligaments heal poorly in horses. Therefore, the use of iPS cells in these animals may help enhance long-term tissue repair.” Further research will be required to develop clinical treatments.

Science Daily
March 8, 2011

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Hormonal therapy for older, pregnant horses?

Like humans, horses are prone to miscarriage. In fact, about one in ten pregnancies results in miscarriage at a very early stage. Some horses have a history of early miscarriages and it has become customary to treat them with a type of progestin known as altrenogest, although there have not been any studies to assess whether this actually improves the chances that the pregnancy will run to term. The group of Christine Aurich at the University of Veterinary Medicine, Vienna has now investigated the effect of altrenogest treatment on the development of the foetus and on the horses’ hormone levels. Surprisingly, the researchers found that the foetus developed significantly more slowly in older mares compared with younger animals. The difference disappeared in horses treated with altrenogest, showing for the first time that the progestin has a positive effect on foetal development. The results are published in the 75th issue of the journal Theriogenology.

Most miscarriages in horses results at very early stages of pregnancy (within about three weeks) and it is generally believed that the primary cause is that the foetus grows or develops too slowly: smaller than normal embryos have a higher chance of being lost then normally sized ones. It is not clear whether low concentrations of progesterone lead to slower embryonic development but nevertheless the progestin altrenogest is routinely used to treat mares that frequently suffer miscarriages. Aurich’s group has now found that altrenogest treatment has no effect on the levels of luteinizing hormone (LH) or progesterone, hormones that are known to be important in maintaining pregnancy. Furthermore, treatment does not influence the ease with which the mares became pregnant, nor does it affect the size of the vesicles housing the embryos, at least for the first 22 days after conception. However, the researchers did notice that at 20 days after conception the embryonic vesicles are smaller if the mares are older. They also found that the foetuses of older mares grow significantly more slowly after this period, although if the mares are treated with altrenogest their foetuses grow at the normal rate.

The smaller size of the foetuses in older mares provides a nice explanation for the higher rate of pregnancy losses as horses grow older. Smaller foetuses in these animals may result from a reduced quality of the eggs as the horses age, making the mares more susceptible to miscarriage. Encouragingly, treatment with altrenogest appeared to enable the smaller foetuses to recover and to grow at a normal rate during the second crucial period in the animals’ development, when the embryonic organs are formed and the mare’s placenta is generated (from 35 to 45 days after conception). It seems conceivable that altrenogest encourages the formation of the placenta. The results show that altrenogest treatment does have an effect in reducing the risk of miscarriage in horses, although not the one that might have been expected. It does not seem able to prevent miscarriages in early pregnancy but instead to compensate for later problems in foetal development that are more frequently encountered as mares grow older. As Aurich says, “We are now well used to the idea of a hormonal therapy in humans to prevent osteoporosis. Perhaps horses cold also benefit from the same type of treatment to help them avoid miscarriages.”

EurekAlert! Medicine
February 8, 2011

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Obesity in horses could be as high as in humans

At least one in five horses used for leisure are overweight or obese. It’s a condition which can lead to laminitis and equine metabolic syndrome. The pilot study, carried out by The University of Nottingham’s School of Veterinary Medicine and Science, showed that rates of obesity among horses are likely to be just as high as they are among people. The results are published online in the journal Veterinary Record. The study, by third year veterinary student Helen Stephenson from Lydney in Gloucestershire, assessed the prevalence of obesity among horses whose owners were registered with Oakham Veterinary Hospital — one of the school’s clinical associates specialising in the treatment of horses. Research carried out in Scotland has already shown a prevalence of obesity in pleasure riding horses but this is the first time a similar study has been done in England. Five hundred owners were sent questionnaires. None of them kept horses for breeding, livery, riding stables, or competition, so were all classed as keeping their animals for leisure only. Of the 160 returned one in five showed that their horses were either overweight or obese.

The research was supervised by Dr Sarah Freeman, a specialist in Veterinary Surgery at the vet school. Dr Freeman said: “This provides the first snapshot of the prevalence of obesity in horses in the UK and an insight into owners’ management of bodyweight in horses. Obesity is linked to a number of different diseases, including arthritis, laminitis and equine metabolic syndrome. A larger study would be useful to establish the prevalence and risk factors for equine obesity in different horse populations across the UK.” The owners were asked about their perceptions of their horses’ body condition, and asked to score this from zero to five, with a score of more than 3 indicating overweight. Grass was the main source of forage for half the horses and coarse mix was the main source of concentrate feed in a similar proportion. Only one in 10 horses was not fed any concentrate.

The researchers then assessed the body condition of 15 randomly selected horses to see if the scores had under or overestimated the horse’s weight. They assigned an average score that was significantly higher for these horses; eight of the owners had scored their horse at least one grade lower than the researcher had, indicating that the owners had underestimated their horses’ weight. On the basis of the researchers’ findings, the authors estimate that the true prevalence of overweight/obesity was likely to be 54% rather than the 20% indicated by the questionnaire responses. Increasing incidence of obesity is a multi-species problem, affecting both humans and their companion animals. I feel that addressing this issue is an important role for the profession, and I hope to do my part when I go into practice. Helen said: “Increasing incidence of obesity is a multi-species problem, affecting both humans and their companion animals. I feel that addressing this issue is an important role for the profession, and I hope to do my part when I go into practice.”

Science Daily
February 8, 2011

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How to minimize stress when horses are first ridden

The horse was domesticated many thousands of years ago and has been hugely important in the development of human civilization. It is hard to overstate its role in agriculture, in transport and communications and even in military operations. More recently, equestrian sports have gained markedly in popularity, so even though the horse has largely been superseded in modern farming and military practice its connection to man remains as close as ever. Nevertheless, the horse retains at least some aspects of its wild origins. It is clear that horses are frequently subjected to situations that would be extremely stressful for genuinely wild animals, such as training of racehorses, performance in equestrian competitions, examinations by vets and transport by road. Indeed, all of these are known to be associated with stress reactions in horses. Even being ridden could represent a source of stress but there have to date been very few studies on this aspect. Recent work by Alice Schmidt in the group of Christine Aurich at the University of Veterinary Medicine, Vienna has for the first time examined the stress suffered by young horses when they are trained to be ridden.

Schmidt measures stress by examining the horses’ heartbeats and the levels of the stress hormone cortisol in their saliva. In looking at heartbeats she considers not only their frequency but also the short-term fluctuations in intervals between the beats, which have previously been shown to be a good indicator for stress. Training of sports horses usually starts when the animals are three years old, so for her recent work Schmidt examined horses of this age at the start of their initial training regimes. Perhaps not surprisingly, she found that the start of training was a stressful period. The initial work on the lunge caused only a moderate amount of stress but the stress level rose markedly when the rider first mounted. This was revealed by an immediate increase in heartbeat and in the fluctuations in intervals between individual beats, as well as by the release of cortisol into the saliva. It seems likely that the horse interprets the first mounting of a rider as a potentially lethal attack by a predator, from which it is unable to escape. In addition, the rider is outside the horse’s field of vision, which presumably exacerbates the problem.

Perhaps surprisingly, when the horse and rider walk or trot forwards, the level of stress decreases somewhat. It thus seems as though the horse adapts rapidly to the idea of being ridden and that — as is the case for humans — exercise may help relieve stress. Furthermore, the extent of stress caused by mounting was found to decrease gradually as the horse is trained, providing that this is done correctly. Aurich cautions that a lack of care or an incorrect regime in early training could cause long-term damage to the relationship between a horse and its rider and thus prevent a sports horse from reaching its full potential as well as causing the animal unnecessary anxiety. Although her results make clear for the first time that the initial training of a sports horse does stress it, Schmidt has some reassuring words for trainers and jockeys. “The stress caused by being ridden for the first time is nowhere near as much as that caused by being transported by road. And if you are gentle and careful when you start to train a young horse, it will soon get used to you.”

Science Daily
October 12, 2010

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Who’s your mommy?

Sleek, speedy, and spirited, thoroughbred horses arose from Arabian stallions more than 3 centuries ago. But who were the mares that birthed these noble steeds? A new genetic analysis suggests that thoroughbred foremothers hailed from Ireland and Britain. In the late 1600s and early 1700s, three stallions imported by British aristocrats became the famous forefathers of today’s thoroughbreds: the Godolphin Arabian, Darley Arabian, and Byerley Turk. The three originated in the Middle East region but came to England through different paths: one was purchased in France, one acquired in Italy, and the third captured from a Turkish officer at the Battle of Buda in 1686. “We know their names and we have paintings of them,” says Mim Bower, an archaeogeneticist at the University of Cambridge in the United Kingdom. Breeders also know a lot about the horses’ descendants, as they carefully recorded the lineages over the centuries.

But no one kept track of the moms. “Nobody gave a shit about the females,” says Greger Larson, an evolutionary biologist at Durham University in the United Kingdom who was not involved in the study. In the early days, breeders thought the important parent was the stallion, says Bower; any old mare would do as a mother. Many breeders assumed that the original mothers were native British horses. But in the early part of the 20th century, some breeders came to believe that thoroughbreds’ mothers were also Arabians—probably because this idea seemed more aristocratic. Bower and her colleagues set out to settle the debate with genetics. They focused on DNA housed within mitochondria—the cell’s power plants. Mitochondrial DNA is passed down only by the mother, allowing researchers to trace maternal lineages, and it can be linked to particular geographical regions. The researchers analyzed DNA from about 300 thoroughbreds and nearly 2000 other horses of different breeds from across Europe and Asia. Most of the sequences came from a genetic database, but the researchers also wrote letters and made phone calls to horse people, asking for samples. “We ask people to pull hair,” says Bower. Most owners go for a clump of mane hair—horses don’t take too kindly to having their tails pulled. The team then sequenced short stretches of DNA extracted from the tissue attached to the hair.

The thoroughbreds’ mitochondrial DNA sequences were closest to those of native Irish and British breeds, like the Connemara. There was a hint of other ancestries—including Arabian—but thoroughbred moms most likely hailed from the British Isles, the researchers will report online tomorrow in Biology Letters. The fact that breeders ignored the contribution of females reveals the prejudices of society at the time, says Larson. “Just how fantastic is it that we’re learning about human social conventions through a study of domestic animals?” Larson adds, however, that the geographic origins of horses are particularly tricky to pinpoint through genetics, so he’d like to see more data than the relatively short stretch of mitochondrial DNA used in this study. Using new high-throughput genetic techniques to analyze a lot more DNA “would nail this shut,” he says.

ScienceNow
October 12, 2010

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Cotton rats and house sparrows as hosts for North and South American strains of Eastern equine encephalitis virus

Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) is an arbovirus that causes severe disease in humans in North America and in equids throughout the Americas. The enzootic transmission cycle of EEEV in North America involves passerine birds and the ornithophilic mosquito vector, Culiseta melanura, in freshwater swamp habitats. However, the ecology of EEEV in South America is not well understood. Culex (Melanoconion) spp. mosquitoes are considered the principal vectors in Central and South America; however, a primary vertebrate host for EEEV in South America has not yet been identified. Therefore, to further assess the reservoir host potential of wild rodents and wild birds, we compared the infection dynamics of North American and South American EEEV in cotton rats (Sigmodon hispidus) and house sparrows (Passer domesticus). Our findings suggested that each species has the potential to serve as amplification hosts for North and South America EEEVs.

Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) is an arbovirus that causes severe neurologic disease in humans in North America and in equids throughout the Americas. EEEV strains that circulate in North America and the Caribbean (NA EEEV, lineage I) are distinguishable from those that circulate in Central and South America (SA EEEV, lineages II–IV) by the following: antigenicity (4 distinct subtypes), genetics (20%–25% nt sequence divergence), phylogenetic and evolutionary patterns, epidemiology, human pathogenicity, and geographic distribution. One theory for their markedly different characteristics is that EEEV adapted to a unique North American ecologic niche after its introduction and evolutionary divergence from EEEV in Central and South America. Although the ecology of vectors and vertebrate hosts for NA EEEV has been well defined, the ecology for SA EEEV remains poorly characterized, which limits our understanding of the divergence of these viruses.

Enzootic circulation of EEEV in eastern North America is primarily supported by a variety of avian reservoirs in the order Passeriformes and by the highly ornithophilic mosquito vector, Culiseta melanura, in freshwater swamp habitats. However, under favorable amplification conditions, sporadic epizootic and epidemic transmission occurs by bridge vectors (e.g., Aedes spp. mosquitoes) that have more catholic feeding behaviors. These vectors have the ability to broaden the virus’ amplification host range to other avian or mammalian species in habitats that pose greater risk for incidental hosts, such as humans and equids. For example, recent studies in some southeastern foci of North America suggest that enzootic and/or epizootic EEEV transmission may involve ectothermic hosts (e.g., reptiles and amphibians) and herpetophilic mosquito vectors. Rodents have not been implicated in transmission of enzootic NA EEEV; however, seroprevalence data support their susceptibility to infection and warrant consideration of their potential to serve as vertebrate hosts during epizootic transmission.

Isolation of SA EEEV from Culex (Melanoconion) spp. mosquitoes in the Spissipes section (e.g., Cx. pedroi, Cx. taeniopus) suggests that they are the principal enzootic, and potentially epizootic, mosquito vectors in Central and South America. These mosquito species have broad host preferences–mammalian, avian, and reptilian–but the primary vertebrate host for SA EEEV has not yet been identified. Virus isolations and seroprevalence data demonstrate that wild birds, rodents, marsupials, and reptiles are susceptible to infection. However, the involvement of these vertebrates in the enzootic transmission of SA EEEV remains unclear.

Venezuelan equine encephalitis virus (VEEV) is the closest genetic relative to EEEV and circulates sympatrically with SA EEEV. Like SA EEEV, Culex (Melanoconion) spp. mosquitoes serve as the primary enzootic vectors of VEEV. Small mammals are the principal reservoir hosts of VEEV, although a wide variety of vertebrate species have antibodies against VEEV. Phylogenetic comparisons of SA EEEV and enzootic VEEV subtypes ID and IE have shown similar patterns of evolution that are consistent with the use of mammalian vertebrate hosts rather than the avian hosts involved in NA EEEV transmission. Therefore, the similarities in geographic range, vector ecology, and phylogenetic profiles of SA EEEV and VEEV support the hypothesis of similar mammalian vertebrate host usage, unlike the avian host usage for NA EEEV.

To further test this hypothesis of differential vertebrate hosts for NA versus SA EEEV strains, we compared their infection dynamics in a wild rodent (cotton rat, Sigmodon hispidus) known to support VEEV transmission and in a passerine bird (house sparrow, Passer domesticus) known to be a competent host of NA EEEV. Our goals were to better understand the ecology of SA EEEV, which will help clarify the extent to which these viruses have ecologically diverged and the parameters contributing to or limiting the potential emergence or adaptation of EEEV in naive environments.

Emerging Infectious Diseases
September 14, 2010

Original web page at Emerging Infectious Diseases

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West Nile virus range expansion into British Columbia

In 2009, an expansion of West Nile virus (WNV) into the Canadian province of British Columbia was detected. Two locally acquired cases of infection in humans and 3 cases of infection in horses were detected by ELISA and plaque-reduction neutralization tests. Ten positive mosquito pools were detected by reverse transcription PCR. Most WNV activity in British Columbia in 2009 occurred in the hot and dry southern Okanagan Valley. Virus establishment and amplification in this region was likely facilitated by above average nightly temperatures and a rapid accumulation of degree-days in late summer. Estimated exposure dates for humans and initial detection of WNV-positive mosquitoes occurred concurrently with a late summer increase in Culex tarsalis mosquitoes (which spread western equine encephalitis) in the southern Okanagan Valley. The conditions present during this range expansion suggest that temperature and Cx. tarsalis mosquito abundance may be limiting factors for WNV transmission in this portion of the Pacific Northwest.

West Nile virus (WNV) is a vector-borne flavivirus that is transmitted in an enzootic cycle between birds by mosquitoes; incidental transmission to humans occurs during periods of intense amplification, typically in late summer in the Northern Hemisphere. WNV activity is inherently dependent on environmental and ecologic conditions that affect avian and vector populations because of the role these groups play in WNV transmission. Environmental factors such as temperature, precipitation, and drought, and ecologic conditions such as vector abundance have been identified as possible determinants of WNV activity. Canada represents the northernmost range of WNV in North America. The first positive WNV indicators appeared in Canada in 2001 when the virus was detected in birds and mosquitoes in Ontario. A total of 394 human cases occurred in Ontario and 20 in Quebec during 2002. The virus quickly spread westward into the prairie provinces: 947 confirmed cases in Saskatchewan in 2003, of which 63 were West Nile neurologic syndrome (WNNS), 144 in Manitoba (35 WNNS), and 275 (48 WNNS) in Alberta. A second major outbreak occurred in Canada in 2007, a total of 1,456 (113 WNNS) cases were confirmed in Saskatchewan, 587 (72 WNNS) in Manitoba, and 318 (21 WNNS) in Alberta. Although mostWNV activity has occurred in the southern parts of the country, the virus has been detected as far north as Meadow Lake, Saskatchewan (54°08′N).

Despite this widespread activity, no local WNV transmission was detected in Canada’s westernmost province, British Columbia, during the WNV seasons (May to October) of 1999–2008. The absence of WNV in British Columbia during this period puzzled provincial public health experts, who had been preparing for the virus’s arrival since 2002; some speculated that British Columbia did not contain the prerequisite environmental and ecologic conditions essential for WNV activity. However, in August 2009, a long-delayed range expansion of WNV into British Columbia was confirmed; 2 locally acquired cases in humans, 10 positive mosquito pools, and 3 cases in horses were detected by provincial surveillance.

The official arrival of WNV in British Columbia puts to rest the question of whether the province can sustain within-season WNV activity. However, new questions have been raised relating to the mechanism of viral introduction, the environmental conditions that limited previous WNV activity in the province, the focus of WNV activity in the southern Okanagan Valley, and whether British Columbia can sustain activity between seasons. We examined spatial and temporal patterns of WNV activity in British Columbia in relation to mosquito abundance and temperature conditions present during the observed range expansion of 2009. Our goal was to identify potential determinants of WNV activity along this portion of British Columbia’s northern and western ranges and to provide additional information regarding factors that facilitate the spread of WNV in North America.

Emerging Infectious Diseases
August 17, 2010

Original web page at Emerging Infectious Diseases

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First cloned horse using oocytes from a live mare

Researchers at Texas A&M University College of Veterinary Medicine & Biomedical Sciences have achieved another cloning first with the successful delivery of a foal using oocytes from a live mare, the first such clone in the world. The delivery of the foal highlights Texas A&M’s long tradition of leading science in equine reproduction, and has been a great experience for the owner of the new foal. I’ve always liked having three horses to ride,” said Kit Knotts, proud owner of Mouse, the foal that represents the successful cloning efforts and the latest in equine reproduction science at Texas A&M University College of Veterinary Medicine & Biomedical Sciences. “I called and emailed breeders to spread the word that I was looking. Everything I could turn up was too small, too young, too old, not quite sound, etc. I realized I didn’t want just another horse to have another body in the barn, I wanted another Marc.”

Knotts’ efforts to find a horse that had the same qualities as her prized Lippizan stallion, Marc, (Pluto III Marcella) would lead her to Texas A&M University and equine reproduction expert, Dr. Katrin Hinrichs. “My local veterinarian, Dr. Brad Newman, mentioned that Texas A&M was cloning, but it was when Dr. Adam Eichelberger joined Newman Equine that we began to pursue the possibilities.” Dr. Hinrichs’ lab is noted for achieving the first cloned foal in North America, and the third in the world with Paris Texas, who arrived in 2005. The lab has since produced twelve cloned foals. Currently there are only three labs in the world that have reported the successful birth of cloned horses — Texas A&M University, Viagen (a commercial venture based in Texas), and the lab of Dr. Cesare Galli, in Italy. “We have worked on this clone for about two years,” said Hinrichs, a professor in the Department of Veterinary Physiology & Pharmacology. “This is actually our first foal produced using oocytes, or egg cells, from live mares. We recovered the oocytes from our herd of research mares using the same method used to recover eggs from women for in vitro fertilization. We used the oocytes for the cloning process, which made it difficult as we had very few to work with at any one time. During the cloning process, we tested a new technique that has been reported in mice to decrease birthing problems. Mrs. Knotts has been very supportive of our efforts to clone her horse, and has even named the foal ‘Mouse’ in honor of the research that produced him.”

The process began with a biopsy of skin cells from Marc, the horse to be cloned. Through the cloning process using oocytes recovered from a live mare, viable embryos were developed and sent to Hartman Equine Reproduction Center, an embryo transfer facility in North Texas which works closely with Hinrichs’ lab, for transfer into surrogate mares. Minnie, the mare carrying Mouse, stayed in North Texas for approximately 200 days, then was sent to her new home in Florida. Minnie began to show signs of an early delivery, and was taken to the University of Florida College of Veterinary Medicine for observation and intervention. That’s where Mouse arrived and was cared for by a team of neonatal experts that helped make sure he would make it through this critical time. “Having Minnie with us for several months prior to foaling has been great,” added Knotts. “The teamwork between Dr. Hinrichs and her colleagues at the University of Florida has been outstanding, frankly saving Mouse’s life more than once before and after birth. Hinrichs noted that while Mouse is truly an identical twin to the original horse, Marc, that there will be differences as the foal grows due to environmental influences.

Science Daily
July 6, 2010

Original web page at Science Daily

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Isolation and characterization of highly pathogenic avian influenza virus subtype H5N1 from donkeys

The highly pathogenic H5N1 is a major avian pathogen that crosses species barriers and seriously affects humans as well as some mammals. It mutates in an intensified manner and is considered a potential candidate for the possible next pandemic with all the catastrophic consequences. Nasal swabs were collected from donkeys suffered from respiratory distress. The virus was isolated from the pooled nasal swabs in specific pathogen free embryonated chicken eggs (SPF-ECE). Reverse transcriptase polymerase chain reaction (RT-PCR) and sequencing of both haemagglutingin and neuraminidase were performed. H5 seroconversion was screened using haemagglutination inhibition (HI) assay on 105 donkey serum samples. We demonstrated that H5N1 jumped from poultry to another mammalian host; donkeys. Phylogenetic analysis showed that the virus clustered within the lineage of H5N1 from Egypt, closely related to 2009 isolates. It harboured few genetic changes compared to the closely related viruses from avian and humans. The neuraminidase lacks oseltamivir resistant mutations. Interestingly, HI screening for antibodies to H5 haemagglutinins in donkeys revealed high exposure rate. These findings extend the host range of the H5N1 influenza virus, possess implications for influenza virus epidemiology and highlight the need for the systematic surveillance of H5N1 in animals in the vicinity of backyard poultry units especially in endemic areas.

BioMed Central
April 27, 2010

Original web page at BioMed Central

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Horse genome bet pays off

Thoroughbred horse owners now have a new tool to predict how their nags will perform on the track. On Friday, a new company called Equinome rolled out a €1000 DNA test of a muscle factor derived from the Horse Genome Project at the Irish Thoroughbred Breeders’ Association Expo in County Kildare. Muscle growth is governed by myostatin, a protein that determines whether an animal has compact muscles tuned for rapid sprints or a leaner body suited for endurance. Company co-founder Emmeline Hill, a genetics researcher at University College Dublin, and colleagues reported last month in PLoS ONE that horses with two copies of the myostatin-suppressing C variant of the gene were more likely to win short races up to 6.5 furlongs (1.3 kilometers), whereas horses with two T variants did better in races up to 13.5 furlongs. Horse Genome Project coordinator Ernest Bailey of the University of Kentucky, Lexington, notes that breeders have adopted genetic tests for paternity, coat color, and diseases but that performance prediction is new ground. Hill says breeders have been asking about genes for temperament. That’s not yet in the offing, she says, but “we’re investigating gene associations with other parameters, such as aerobic capacity.”

ScienceNow
February 23, 2010

Original web page at ScienceNow