Horses that won't lose weight may need stricter diet

Some obese horses and ponies may need to have their diets restricted more severely than previously thought in order to help them lose weight according to new research.

The studies were conducted  at the University of Liverpool. They showed that although some obese animals will lose weight, in an appropriate way,  on a diet restricted to 1.25% of body weight (on a dry matter basis), others may need their diet restricted to as little as 1% of body weight in order to shift those surplus pounds. Such animals have been described as being ‘weight loss resistant’ in a  report  presented at the WALTHAM International Symposium in September.

The work has been published as an abstract in the proceedings of the 5th European Workshop on Equine Nutrition and will be written up and published as a full paper in due course. It was funded by the government-initiated Knowledge Transfer Partnership and the WALTHAM Equine Studies Group.

The study, which was conducted over 16 weeks, involved 12 overweight/obese horses and ponies of mixed ages and breeds, with body condition scores of between 7 and 9 (1 being emaciated and 9 being obese). They were individually housed on wood-shavings and provided with a balanced fibre-based diet at 1.25% of body weight. They were allowed daily access to a bare paddock but no structured exercise was given. Eight of the horses achieved a slow, gradual but consistent loss of body weight over the study period, but weight loss was much slower in the remaining four.

These four horses, deemed to be weight loss resistant, were monitored for a further four weeks during which their diet was reduced to 1% of body weight daily. This significantly increased their rate of weekly weight loss, to a level comparable to the weight loss seen in the other eight horses in the original study. It is thought that genetics may account for such individual differences in sensitivity to weight loss. In all cases the horses remained healthy and no stereotypic behaviours were seen.

Dr Caroline Argo explained: “It is important to understand that the appetite of obese ponies will drop to around 2% of body weight (dry matter) yet their body weight will be maintained or they may even continue to gain in weight. If weight loss is to be stimulated, food intake must be limited quite severely.”

Clare Barfoot BSc (Hons) RNutr, the research and development manager for SPILLERS® and a member of the research team added: “Controlled but balanced nutrition, under careful veterinary guidance, is essential to promote weight loss in overweight or obese horses and ponies, especially when exercise is not an option but we have had little evidence-based advice on how far the diet can be restricted safely to help shed weight in stubborn cases until now.”

“In practice where exercise can be used to increase energy expenditure, such severe restriction may not be required; in this situation access to grazing must be reduced, exercise increased and a low calorie high fibre forage fed in a monitored way alongside an appropriately formulated forage balancer.”

The Horse Nutrition Handbook

Pour-on deworming

Topical applications are easy to administer and may reduce the risk of injury to the operator. Pour-on anthelmintics have become popular for treating cattle and have been shown to be effective. However, experts disagree on the value of pour-on preparations for deworming horses.

A study, supervised by Professor Adolfo Paz-Silva at the University of Santiago de Compostela in Spain, and published in the Equine Veterinary Journal, examined the use of a pour-on anthelmintic in naturally infected Pura Raza Galega horses.

Over a 21-week period, the researchers compared the fecal worm egg production in untreated animals and in horses treated with ivermectin pour-on (at double the cattle dose rate.)

The feces were clear of strongyle eggs between 3 and 9 weeks after treatment. Strongyle eggs reappeared in the feces 10 weeks after treatment. Topically administered ivermectin suppressed fecal egg production of Parascaris equorum and Oxyuris equi for the whole of the study period.

The researchers concluded that the pour-on ivermectin preparation was highly successful against gastrointestinal nematodes. They suggest that it appears to provide a useful treatment option for large groups of horses at pasture.

However, a report by Dr Cengiz Gökbulut and others published in Veterinary Parasitology paints less favorable picture.

The study looked at the absorption of ivermectin after oral, topical or intravenous administration and how the mode of administration influenced the efficacy of the treatment.

One group of horses was treated with equine oral ivermectin paste (at 0.2mg/kg); a second with bovine pour-on (at the recommended cattle dose rate of 0.5mg/kg) and a third group was treated with an injectable cattle preparation (given intravenously at 0.2mg/kg).

Compared with the oral paste, the pour-on preparation resulted in lower but more persistent plasma concentrations. It was also less effective at reducing the fecal strongyle worm egg count.

The authors of the report warn that the poor plasma availability after topical application could result in sub-therapeutic levels of ivermectin, which could encourage the development of ivermectin-resistant parasites.

Read more about research into pour-on ivermectin in horses.

Lavender Foal Syndrome test now available.

The Animal Health Diagnostic Center at Cornell University is now offering a genetic test for Lavender Foal Syndrome (LFS).

LFS is a fatal disease of newborn Arabian foals, particularly those of Egyptian Arabian breeding.

Signs shown by affected foals include seizures, nystagmus (involuntary movement of the eyeballs), limb rigidity, paddling movements, and opisthotonus (hyperextension of the head, neck, and spine).

The condition gets its name from the abnormal coat color with which most affected foals are born, variably described as silver sheen, lavender, pale chestnut or pale, dull pinkish grey.

Scientists at Cornell University and the Maxwell H Gluck Equine Research Center have found that Lavender Foal Syndrome is the result of a mutation in a gene called myosin Va (MYO5A). All affected foals tested in the study were homozygous for this mutation (i.e. both copies of the gene were defective).

Lead researcher was Samantha A. Brooks, PhD, assistant professor in the Department of Animal Science at Cornell University's College of Agriculture and Life Sciences.  “Our results suggest that the population frequency of carriers of this deletion is 10.3% in the Egyptian Arabian,” she reports.

“From a practical standpoint, this discovery and the development of a diagnostic test for the LFS allele provides a valuable new tool for breeders seeking to avoid the disease in their foal crop.”

Testing of breeding animals is recommended to identify carrier horses. The breeding program can then be arranged to avoid mating two carriers, and so prevent the birth of an affected foal.

The test can be run on hair roots pulled from the mane or tail, or whole blood samples.

Normally, the AHDC only accepts samples from accredited veterinarians. However, for this test, Arabian owners are encouraged to submit their own pre-paid samples directly to the laboratory.

The Lavender Foal Syndrome test is not restricted to horses within the USA. Shipment of EDTA whole blood samples from abroad requires a USDA permit. However, according to the laboratory no permit is required for sending hair samples.

(Permits may not be available for the import of blood specimens from some countries. Please contact the laboratory (Lisa Bowen-Laue; 607-253-3938) for the appropriate permit if you wish to submit EDTA whole blood for LFS testing from outside the USA.)

Each sample must be sent with a completed LFS assay submission form. Payment, ($47 for each horse tested) must accompany the samples unless they are submitted by a licensed veterinarian.

Information on the new test, including full instructions on how to submit samples, can be found on the LFS page of the Cornell University College of Veterinary Medicine website.

Do shock waves aid healing?

Exuberant granulation tissue ("proud flesh") is a common complication of wounds to the horse's lower limbs. It may delay healing and make scar formation more likely.

Dr Andressa Silveira and colleagues at the University of Guelph in Ontario, Canada, have been examining whether shock wave therapy could be used to promote healing and reduce the risk of exuberant granulation tissue.

They found that wounds treated with unfocussed extracorporeal shock wave therapy (ESWT) seemed to produce less exuberant granulation tissue, and looked healthier than untreated wounds, although they did not heal more quickly.

The researchers made five full-thickness skin wounds, (2.5 cm x 2.5cm) on the dorsal aspect of the metacarpus of both fore limbs of each of six horses.

They treated one leg from each horse with ESWT, and left the other limb untreated to act as a control.

The wounds were treated immediately after they were made and then at weekly intervals for a total of four occasions. Each treatment comprised 625 pulses - distributed evenly around the wound and surrounding healthy skin edges.

The researchers found that control wounds were more likely (1.9x) to appear inflamed than were treated wounds. Untreated wounds also had higher exuberant granulation tissue scores.

However, there was no significant difference between biopsies taken from treated and untreated wounds at weekly intervals throughout the study. Neither did treatment have any effect on wound size.

Further investigations are required before shock wave therapy can be recommended for wound treatment. ESWT may be helpful, but so far, there is not enough evidence to support its use in clinical cases.

Not all bad news about dewormers

There are numerous reports of the spread of resistance to dewormers.  So it is encouraging to receive some good news for a change.

Research carried out by Dr Craig Reinemeyer and others at East Tennessee Clinical Research Inc., has revealed some positive findings.

In separate studies they examined the efficacy of dewormers against Oxyuris equi, and against macrocyclic lactone resistant Parascaris equorum.

Oxyuris equi (equine pinworm) rarely causes serious problems for the horse, but does cause irritation when the female lays the sticky eggs on the skin around the anus of the host. It has been assumed that most routine dewormers will control it. However, anecdotal reports that anthelmintic treatments were not as effective against Oxyuris equi as expected prompted Dr Reinemeyer’s study.

Dr Reinemeyer found that pyrantel pamoate (at 13.2mg/kg) was 91.2% effective, and ivermectin (200mcg/kg) 96.0% effective, against the adult worms. Both products were more than 99% effective against the fourth-stage O. equi larvae.

Unlike O. equi, Parascaris equorum does cause significant problems, especially in foals, in which heavy infestations can lead to intestinal obstruction or rupture.

Recent reports have recorded an increasing problem of reduced efficacy of macrocyclic lactone anthelmintics (such as ivermectin) against these parasites.

In a study of experimentally infected foals, the researchers found that pyrantel pamoate administered at 13.2mg/kg was effective against a macrocyclic lactone -resistant (ML-R) isolate of Parascaris equorum.

Mean ascarid egg counts were reduced by 98.8% two weeks after treatment - compared with a reduction of only 47% two weeks after ivermectin (200mcg/kg). Post mortem examination of intestinal contents showed that the paste formulation of pyrantel pamoate was 97.3% effective against the MLR P. equorum.

It is reassuring to know that these drugs were effective under the specific conditions of the study.  But that’s not to say that they will always remain so, or that the results are representative of all worm populations. The advice to treat for worms only when necessary and to monitor the effectiveness of any treatment still stands.

Measuring tear production

We may need to look again at how we treat eye infections in the light of research that found that horses produce more tears than previously thought.

Tears protect the eye by keeping the cornea moist. The tear film also carries nutrients to the cornea, which has no blood supply of its own.

The same route is also used to deliver medication to the cornea.

How many tears does a healthy horse produce? How quickly is the tear film replaced? There have been few studies into this, yet it is important to know, as it will affect the concentration of drugs applied to the eye - and so may affect their efficacy.

Dr Thomas Chen and Dr Daniel A. Ward examined the rate of production of tears in normal horses' eyes, in a study carried out at the College of Veterinary Medicine, University of Tennessee, Knoxville. They instilled fluorescein dye onto the eye and then collected small samples of the tear film, measured the fluorescein concentration, and noted how it changed with time.

They used two mathematical approaches to analyse the results. One method, which was considered the more accurate, suggested that the rate of tear production was 33.6mL /min. The mean tear film volume was estimated to be 233.74 mL.

The results showed that the tear film was likely to be completely replaced within a matter of 7 minutes. This suggests that current treatment protocols may not be adequate, and that drugs may need to be administered more frequently.

Read more at  the Equine Science Update website

Measuring weight loss

Belly girth measurements provide  a better way of assessing early weight loss according to recent research.

One of the problems faced by owners of overweight horses, is monitoring the response to weight loss programmes. Obviously weighing the horse would be ideal but is often not possible. Weigh tapes placed around the heart girth (just behind the elbow) may not detect any change despite a decrease (or increase ) in body weight, because that is not where the excess fat is deposited.

Two recent weight loss studies have both shown that belly girth measurements are more closely related to changes in bodyweight in early weight loss (after the first week of feed restriction) as opposed to the more commonly used heart girth measurements. Belly girth measurements are taken at the widest point of the belly - approximately two thirds of the way between the point of the shoulder and the point of the hip. They may even be more accurate than some ultrasound fat measurements.

One study conducted last year by researchers at the Department of Veterinary Clinical Science at the University of Liverpool and supported by World Horse Welfare, highlighted the need for a more accurate method for monitoring early weight loss in overweight ponies rather than relying on conventional equine body condition scoring.

A further study comparing two practical weight loss protocols for the management of overweight and obese horses and ponies was conducted earlier this year by the Department of Veterinary Clinical Science at the University of Liverpool. It was funded by the government-initiated Knowledge Transfer Partnership and the WALTHAM Equine Studies Group. It confirmed that the proportional change in belly girth was more closely associated with changes in body weight than the proportional change in heart girth in the early stages of weight loss.

Dr Caroline Argo and Alex Dugdale of the Department of Veterinary Clinical Science at the University of Liverpool said: “It is important for owners to understand that early weight loss is not immediately recognisable as a change in the horse or pony’s overall appearance or body condition score. However, owners do need some assurance that measures taken to promote weight loss are being effective. Simply measuring belly girth at regular (weekly) intervals can provide this. Without such reassurance, we might be inclined to either give up or more alarmingly, harmfully increase our efforts to induce weight loss.”

See Equine Science Update for more information

Equitation science discussed in Sweden

Horse welfare and rider safety can be enhanced by the application of new technology to the training of both horse and rider. That was one of the messages to come out of the 6th International Society for Equitation Science conference held recently in Sweden.

In the past few years there has been a growing interest in equitation science (the science of horse riding and horse training.) A selection of recent research, covering a wide range of topics, was presented at the conference, held this year at the Swedish University of Agricultural Sciences (SLU) in Uppsala.

Presentations covered training and education of horses and riders, from both a scientific and a practical perspective, and highlighted the importance of a thorough understanding of learning theory and physical capacities of the horse to safeguard horse welfare and human safety.

The first day focused on the mental and physical capacity for training and learning in both horses and humans.

The conference, attended by almost 200 delegates, also included practical demonstrations which took place at the Swedish National Equestrian Centre at Strömsholm.

Teachers from Strömsholm and the national stud at Flyinge demonstrated their approach to teaching young riders and training horses. Scientists from SLU presented examples of ongoing research projects, and showed how emerging technologies can measure important variables such as the pressure under saddle and the distribution of lameness.

The last day focused on the latest research in the field of horse welfare and human safety and, in a final panel discussion, the conference explored how these two topics can positively affect each other.

Abstracts of the presentations are available in pdf format for (free) download from the ISES website.

Managing pasture to reduce laminitis risk

A new report provides owners with practical information on how to manage their pasture to reduce the risk of laminitis in horses and ponies.

The search for improved meat, milk and fibre production has led to the development of grasses containing high levels of non structural carbohydrates (NSC- sugar, starch, and fructan).

The non-structural carbohydrate content can increase dramatically if the pasture is exposed to extreme conditions - such as intense sunshine, drought and cold stress. Such pasture presents a high risk for horses and ponies susceptible to obesity, insulin resistance and laminitis.

But with good pasture management, these conditions can be minimised.

The report, entitled "Equine Laminitis - Managing pasture to reduce the risk", is written by US -based agronomist Kathryn Watts and Professor Chris Pollitt, Director of the Equine Laminitis Research Unit at the University of Queensland, and published by Australia's Rural Industries Research and Development Corporation (RIRDC). It outlines how horse owners can reduce the level and concentration of sugar, starch and fructan in their pastures. High levels of these carbohydrates can cause laminitis in horses and ponies.

According to Professor Pollitt, the report represents an important step forward in the understanding of pasture associated laminitis.

“While there are still significant gaps in our knowledge about laminitis, a source of great frustration to horse owners and veterinarians alike, we do know that what the horse or pony has eaten over the last few days, weeks or months may trigger laminitis,” Professor Pollitt said.

Equine Laminitis – Managing pasture to reduce the risk can be purchased in hard-copy for $A25 or downloaded (free) in PDF format. See: www.rirdc.gov.au

Response of aged horses to vaccination

How does age affect the horse’s ability to respond to vaccination?

As with other body systems, the immune system undergoes age-related changes (known as "immunosenescence"). This may make the animal more prone to infections and autoimmune and neoplastic diseases.

A research team from the Atlantic Veterinary College, Prince Edward Island, Canada conducted a study to investigate the  specific systemic antibody response in horses by looking at how they responded to vaccination. They compared the response of young adult horses (aged 4 - 12 years) with aged horses (20years or older).


To investigate the primary immune response to an antigen that the horses would not have experienced before, they used rabies vaccine. Prince Edward Island is rabies-free and none of the horses had been vaccinated  previously for the disease.

They found that healthy aged horses vaccinated against rabies  showed a primary immune response similar to that of younger adults. However, by 6 months after vaccination the rabies antibody titres fell significantly in both age groups.

To test the anamnestic response (the rapid production of specific antibodies on renewed exposure to the antigen) they monitored the response to influenza vaccination. The anamnestic response was significantly reduced in the aged horses. Younger horses showed a significantly greater increase in two classes of anti-influenza antibody (IgGa and IgGb) after vaccination, compared with aged horses. This was despite the older horses having higher antibody levels at the start of the study.

Tiludronate effective for bone spavin

Horses suffering lameness due to bone spavin can show marked improvement following treatment with a tiludronate infusion, in combination with controlled exercise, according to recent research.

Bone spavin is a common cause of hindlimb lameness in horses and ponies. Often both hind legs are affected to some extent. Horses with straight or sickle-shaped hocks seem to be at greater risk of developing the condition.

There is little movement between the lower rows of bones in the hock. However these joints are subjected to considerable compressive forces. This can lead to degenerative changes within the bone and destruction of the joint cartilage

In a paper published in the Equine Veterinary Journal, Dr Martin Gough and others describe a double-blind, placebo-controlled trial involving 108 clinical cases of bone spavin.

The horses were treated at day zero with a single tiludronate infusion or a placebo and reassessed 60 days later after a period of controlled exercise.

Eighty seven horses completed the trials: 42 tiludronate treated horses and 45 placebo cases. By day 60 approximately 60% of the Tiludronate treated horses had improved in lameness by two grades or more, scored on a ten point system.

Tiludronate is believed to work by alleviating the pain associated with abnormal bone lysis.

This research was funded by CEVA Animal Health, manufacturers of Tildren®. For more information visit the website:
www.tildren.com

Making racing safer

What can be done to limit the number of horses dying as a result of racing injuries? It is hoped that  analysis of data on  fatal injuries will offer some suggestions. 

At the third Welfare and Safety of the Racehorse Summit held at Keeneland, Kentucky on June 28 and 29, Dr. Tim Parkin, epidemiologist from the University of Glasgow’s Faculty of Veterinary Medicine, presented a preliminary analysis of racing fatalities in North America from data compiled in the Equine Injury Database (EID).

The analysis was based on data on Thoroughbred flat racing in the EID collected on 73 racetracks between November 1, 2008 and October 31, 2009  - a total of 378,864 starts. Horses that suffered a fatal injury during or immediately after a race, or that died later as a result of an injury that occurred during racing, were included in the analysis.

Among Dr Parkin's findings were:

Starts made by 2-year-olds were less likely to end in fatality than starts made by older horses. Females were not at increased risk of fatality when racing against males. Starts made by females were less likely to end in fatality than starts made by intact males.

No statistically significant difference was found in the incidence of fatality on different surfaces, with different surface conditions, in different race distances, or in horses carrying different weights.

No firm recommendations can be made at this stage. As the data contained in the EID continues to grow, some of the current statistical conclusions may change as a reflection of increased certainty associated with a larger data set.

“This preliminary analysis just scratches the surface,” said Parkin, who serves as a consultant on the Equine Injury Database. “As the number of starts recorded in the database continues to grow, more complex statistical analyses can focus upon multiple variables studied in concert to better understand the myriad of factors which may contribute to fatal and non-fatal injuries. In addition, differences that may not have achieved statistical significance after one year of data collection may do so with additional observations recorded in the database.”

“The work presented today represents a starting point, not a destination,” said Dr. Mary Scollay, equine medical director for the Kentucky Horse Racing Commission and a consultant on the Equine Injury Database. “This begins to answer the question of what is happening. The ‘how’ and ‘why’ remain to be determined.”

for more details see:

http://www.grayson-jockeyclub.org/newsimages/Summitcombinerelease.pdf

Help needed with ragwort survey

British horse riders are being urged to help map the distribution of ragwort in the UK.

The risk to horses of eating ragwort are widely known throughout the equine community. The plant contains poisons that cause progressive liver damage. Even small amounts eaten over time can lead to serious disease.

Despite that, every year the British Horse Society Welfare Department receives numerous reports of horses grazing in fields containing ragwort. “It does seem that the amount of ragwort is on the increase” Lee Hackett, Senior Executive of BHS Welfare,  writes in the latest issue of British Horse, the Society‘s magazine. “This suggests that current control measures aren’t working, but to change things we need evidence.”

In an effort to gain hard data on the extent of the problem, the BHS is organising a snapshot survey during its Ragwort Awareness Week.

Anyone who spots ragwort during the week of 12-18 July is asked to spend a couple of minutes filling in a  simple survey form, which will be available on the homepage of the BHS website.

It is only necessary to report ragwort that is growing in or near to fields being used for grazing horses, sheep or cattle. 

Analysis of the data with mapping software  will show the areas where ragwort is most prevalent.
The number of animals grazing in ragwort-infested fields will also be calculated.

The intention is to repeat the survey in coming years so that trends in the distribution of the plant can be identified.

The BHS has 50 RagForks to give away, generously donated by the manufacturers, eazitools Ltd, who are sponsoring the survey. To be included in the draw for a RagFork you need to include your contact details on the survey form.

More details...

Horse Power CPD supports BEVA Trust & SPANA

Ten senior academics and equine vets from practice have come up with a novel way of raising money to help two worthy equine causes - the SPANA Disabled Riding Centre in Bamako, Mali and the BEVA Trust.

Led by Dr Derek Knottenbelt, they will undertake a 6 day CPD challenge, visiting all 7 British vet schools, to deliver  talks on a variety of subjects.

The lecturers will complete a  whistle-stop tour between the vet schools in convoy, on their motor bikes! They will cover over 1000 miles and deliver around 35 hours of lectures. The lectures are free - but donations are expected.

This marathon effort takes place at the end of July 2010. Places are limited, but anyone can contribute.

Click here to read more about it, or make a donation.

Benefits of exercise on insulin sensitivity

Unless dietary restriction below maintenance energy requirements is also employed, moderate exercise on its own is not enough to counter insulin resistance in obese or overweight horses, according to Dr Rebecca Carter and colleagues at Virginia Tech.

They examined the effects of exercise training alone on overweight or obese, insulin-resistant horses. Feed intake was limited during the study to 100% of maintenance energy requirements.

Eight horses, all either overweight or obese, followed a low intensity exercise program for 4 weeks followed by higher intensity exercise for a further 4 weeks. Finally they had two weeks without exercise (detraining). A control group of four horses received no structured exercise.

The horses’ body weight fell by 2% following the low intensity exercise and by a similar amount after the 4 weeks of higher intensity exercise. However, about half of the body weight lost during the exercise stages was put back on again within the two weeks of detraining with no exercise.

The researchers found no significant difference in glucose or fat metabolism or insulin sensitivity between the exercised and control groups throughout the study.

Dr Carter comments "even though our study did not show long-term training effects of exercise, there still are probably improvements in insulin sensitivity during and shortly after an exercise session. Therefore, ROUTINE exercise (every day) may be beneficial for improving insulin sensitivity."

Read more

Another cloning milestone has been reached by researchers at Texas A&M University with the successful birth of a foal produced using oocytes from a live mare.

Mouse, was born May 5, 2010. The efforts of his owner, Kit Knotts, to find a horse that had the same qualities as her prized Lippizaner stallion Marc, (Pluto III Marcells) led her to Texas A&M University and equine reproduction expert Dr Katrin Hinrichs.

"We have worked on this clone for about two years," said Hinrichs, a professor in the Department of Veterinary Physiology and Pharmacology.  "This is actually our first foal produced using oocytes, or egg cells, from live mares."  She explains that using oocytes from live mares made the process difficult as they had very few oocytes to work with at any one time.

Minnie, the surrogate mare, 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.

Because of the risk of complications and problems in the period just after birth, Dr Hinrichs’ team recommends that foals derived by cloning should be treated as high-risk neonates, and their birth should be closely supervised. Facilities for intensive care should be available in case they are needed.

To read more about the problems faced by cloned foals go to www.equinescienceupdate.co.uk/clone3.htm

Lavender Foal Syndrome

Researchers have identified the genetic mutation responsible for Lavender Foal Syndrome. Lavender Foal Syndrome (LFS), also known as Coat Color Dilution Lethal (CCDL), is a fatal disease of newborn Arabian foals, particularly in those of Egyptian Arabian breeding.

The condition gets its name from the abnormal coat colour with which most affected foals are born, which has been described as silver sheen, lavender, pale chestnut or pale, dull pinkish grey.

Signs shown by affected foals include seizures, nystagmus (involuntary movement of the eyeballs), limb rigidity, paddling movements, and opisthotonus (hyperextension of the head, neck, and spine). The mare often has difficulty giving birth.

A team of scientists from Cornell University and the Maxwell H Gluck Equine Research Center have found that Lavender Foal Syndrome is the result of a mutation in a gene called myosin Va (MYO5A).

The myosin Va transport complex is responsible for the transfer of pigment to the keratinocytes and for transport of transmitter substances in the nerve cells. A mutation affecting the gene could easily result in interference with normal function of melanocytes (responsible for hair color) and nerve cells.

“Our results suggest that the population frequency of carriers of this deletion is 10.3% in the Egyptian Arabian” reports lead researcher Dr Samantha A. Brooks, assistant professor in the Department of Animal Science at Cornell University's College of Agriculture and Life Sciences.

“Given our estimate of the number of carriers in the population we expect that around nine LFS foals would be born in the USA each year”

For more about the research on Lavender Foal Syndrome click here.

Antibiotic resistance in equine faeces

Horses can be a source of antibiotic-resistant bacteria, presenting a threat to human health, according to a recent study.

Mohamed Ahmed, of the Department of Veterinary Microbiology and Parasitology, at Al Fatah, University, Tripoli, Libya, working with colleagues at the Liverpool Vet School, examined fecal samples collected from the University’s equine hospital and from livery yards.

They found antibiotic resistant E. coli in faeces from both locations. From a total of 264 samples, 296 isolates of antibiotic-resistant Escherichia coli were identified.

Not only were hospitalised horses more likely to have antibiotic resistant E. coli in their faeces, they were also more likely than those maintained on livery yards to carry organisms that were resistant to multiple drugs.

Nearly half (48%) of the resistant isolates from the hospital environment showed multiple drug resistance phenotypes, compared with only 12% from the livery yards.

The researchers conclude that, in the UK, horses may provide both recipients, and sources, of antibiotic resistance, MDR, and be an extensive reservoir of antimicrobial resistance genes that could pose a potential threat to human health.

For more details see:

http://www.equinescienceupdate.co.uk/aref.htm

Third Welfare and Safety of the Racehorse Summit

The forthcoming third Health and Welfare of the Racehorse Summit to be held by the  Grayson-Jockey Club Foundation  at the Keeneland Sales Pavilion in Lexington, Ky., June 28-29, 2010, aims to identify ways of enhancing the safety and soundness of Thoroughbred racehorses.

Attendance at the meeting is by invitation only. But you don't need to miss out. Thanks to modern technology and Keeneland.com the public sessions of the summit will be made available to all on a live web stream.

Among the topics to be covered will be an update and preliminary findings on data submitted to the Equine Injury Database. Veterinarian and epidemiologist, Dr. Tim Parkin, of the University of Glasgow, has been analyzing data submitted to the Database, and will provide an update and preliminary findings.

Other topics include a panel discussion on race track surfaces, and updates on the Racing Medication and Testing Consortium, the NTRA Safety and Integrity Alliance, and the Thoroughbred Safety Committee.

There will also be panel discussions on racing equipment and safety,  racetrack environment and training practices, and transitioning thoroughbred racehorses to second careers.


For more information, including the link to the web stream, see:

http://www.grayson-jockeyclub.org/summitDisplay.asp

Deworming horses with Cushing's disease

Horses with Cushing’s disease (also known as pituitary pars intermedia dysfunction ; PPID) are more  likely to have higher fecal egg counts than are healthy horses according to a recent study.

Dr Dianne McFarlane and colleagues compared the response to anthelmintic treatment on fecal egg counts in healthy horses and those with Cushing’s disease.

Twenty-nine healthy horses  (ranging in age from 4 to 35 years ) and 13 horses with PPID (13- 33 years old) were used in the study. The presence or absence of PPID was confirmed by clinical signs and plasma alpha MSH assay (reference range for normal horses <35pmol/L; PPID horses ≥45pmol/L)

The researchers performed faecal egg counts at 2-week intervals before and after treatment with ivermectin.

At 2 and 4 weeks after treatment with ivermectin all horses in the study had negative fecal egg counts.

Horses with PPID had higher egg counts than did healthy horses, both before and at 6 - 12 weeks after treatment.  This difference could not be explained by the PPID horses being older than the control horses, as the researchers found no correlation between age and fecal egg count.

A fecal egg count greater than 200 epg is often taken as an indication that anthelmintic treatment is required. In this study 6 of the 13 horses with PPID reached the 200epg threshold by 10 weeks after ivermectin treatment. In contrast only 2 of 25 control horses had reached the threshold at the same time - a difference that was statistically significant.

“Given similar environmental conditions, horses with PPID were more likely to have higher fecal egg counts than were healthy horses” Dr McFarlane reports.

The findings suggest that horses with PPID may pose a risk for pasture hygiene if not managed properly.

On the other hand, age alone does not appear to increase the horse’s susceptibility to parasitism. However, the researchers point out that only a small number of horses were involved in that analysis. More work is required to confirm that older horses do not need treating differently to younger horses when it comes to deworming.

For more details see:

Fecal egg counts after anthelmintic administration to aged horses and horses with pituitary pars intermedia dysfunction.
D.McFarlane, GM Hale, EM Johnson, LK Maxwell
J Am Vet Med Assoc (2010) 236, 330-334

Prepare for Hendra season Australian horse owners warned

Horses are at increased risk of Hendra virus (HeV) infection at this time of year, the Australian Veterinary Association (AVA) has warned. The disease is usually fatal, and can affect humans that have been in contact with affected horses.

The virus is named after the suburb of Brisbane, Queensland, Australia, in which it was first isolated. In that outbreak in horses at a training centre, 14 horses died. Seven other horses were shown to have been infected and were humanely destroyed. Affected animals typically showed severe lung damage. Two humans were affected, one of whom died.

The natural hosts for the Hendra virus (HeV) are species of fruit bats (commonly known as flying foxes). Antibodies have been found in all four species of fruit bats found in mainland Australia.

“Anyone working with horses should be on the lookout and immediately report any suspected cases of Hendra virus infection over the coming months,” said Dr Barry Smyth, Vice-President of the Australian Veterinary Association.

“Recent mass movements of large flying fox colonies means owners should be especially vigilant.

“Wet weather in some parts of the country has caused flying foxes to take to the air to find food in new areas. An influx of more than 130,000 into Victoria was confirmed by scientists just last week.

“So far cases of Hendra infection have been restricted to Queensland and New South Wales, however there is a potential for the disease wherever there are flying foxes.

Common signs to look out for include respiratory distress, frothy nasal discharge, elevated body temperature (above 40° C) and elevated heart rate. Some horses may show neurological signs including incoordination and head pressing. However, it is important to realise there are no specific signs of infection.

What can you do to limit the risk of horses being exposed to the virus?  “Protective measures include placing feed and water under cover where possible, not placing feed and water under trees when flying foxes are in the area, not using feed that might attract flying foxes (such as fruit and vegetables), and where possible removing horses from fields where flying foxes are active, and fencing off trees where flying foxes roost” Dr Smyth said.

The few cases of human Hendra virus infection have been the result of very close contact with horses infected with the virus. Body fluids or secretions from infected animals are likely to contain the virus.

At the time the people became infected the horses did not appear sick.

“The risk can be greatly reduced by adopting good hygiene practices as a matter of routine and taking increased precautions around any sick horse,” said Dr Smyth.

Experts to advise on equine infectious diseases

Thanks to the opportunities of modern transport, it's not only horses that can travel the world. They may also take with them their infectious diseases.

The recent equine influenza outbreak in Australia showed what can happen when susceptible horses are exposed to infection.

So with all the current scientific knowledge about  vaccination, immunity and infectious disease in horses, What can be done to prevent, control  limit the risk of similar outbreaks disasters events happening in the future.

Recently a group know as the Prevention of Equine Infectious Disease Guidelines Group (PrEquID) has been set up to compile recommendations for preventing and managing major equine infectious diseases, based on current scientific knowledge and available vaccines.

After an initial meeting in November 2009, the group met again in March 2010, to discuss guidelines for Equine Influenza and Equine Herpes virus infections. These diseases are widely considered to have a significant impact on the horse industry, based on disease outcome, economic impact, veterinary care and travel restrictions.

Practical, evidence-based recommendations are currently being finalised and will be made available shortly.

“Our aim is to develop overarching international guidelines for the management of infectious diseases,” said Professor Marian C Horzinek, Chairman of PrEquID. “These should contain practical, evidence-based recommendations for disease control and horse movement.”

Professor Peter Timoney, of the University of Kentucky, added, “the equine industry worldwide is facing an unprecedented threat from the challenge of infectious diseases. It’s a huge industry involving a complex range of stakeholders, including veterinarians, owners, breeders, trainers, shippers and regulators. We must set aside individual and national agendas and concentrate on the bigger picture if we’re to achieve greater international control over the spread of equine diseases and protect our industry for the future.”

The establishment of PrEquID was initiated and sponsored by Fort Dodge Animal Health (a division of Wyeth). With the acquisition of Wyeth by Pfizer in 2009, this initiative is now supported by Pfizer Animal Health.

How does pasture cause lamintis?

Fructans and starch are not responsible for most cases of laminitis, Dr Teresa Hollands told delegates at the Laminitis Awareness 2010 seminar.

Most cases of laminitis occur when horses are eating grass. Pasture associated laminitis accounts for 66% of cases occurring in the UK. But what causes the laminitis?

Experiments have shown that giving large meals of starch or fructans can cause laminitis. Large amounts of these carbohydrates suddenly arriving in the horse’s large intestine disrupt the normal population of bacteria in the gut, leading to a cascade of inflammatory and toxic events.

However, Dr Hollands, nutritionist at Dodson and Horrell, explained that this process is unlikely to be involved in the majority of cases of pasture-associated laminitis.

Firstly, grass contains little starch. Of the pasture plants commonly found in the UK, only clover has significant amounts of starch. Grasses store glucose that they can’t use straight away as fructans.

It has been shown that laminitis can be induced by giving a large bolus of fructan  (5g-12.5g fructan/kg body weight).  That’s about 3.75kg fructan for a 500kg horse.

How much fructan would a horse eat when grazing? Grass contains higher levels of fructan during the winter. Mixed pasture might contain 150g fructan/kg dry matter of grass in the winter (compared with 6.6g/kg in the summer). If a 500kg horse eats an amount of grass equivalent to 2.5% of his body weight, (12.5kg), his total intake of fructans would be about 1.9kg.

So the full daily intake falls short of the levels that have been shown to cause laminitis. And what’s more, as horses are “trickle feeders”, that fructan intake is spread out over 24 hours. So even in the winter when the fructan levels in the grass are highest, the horse is only likely to eat something like 50g fructan/hour. In the summer the figure is likely to be about 5g fructan an hour - a thousand times less than the amount needed to cause laminitis.

What’s more, recent work has shown that fructans are fermented in the small intestine, and so are even less likely to reach the hindgut in sufficient quantities to cause food-induced laminitis.

So how does grass cause laminitis? “We need to move away from thinking about individual components of the diet "  Dr Hollands suggested. “In the end it is the calories that are the main risk factor.”

“Grass provides more than enough calories for most horses in light work.”

She explained that recent work with World Horse Welfare and Napier University used alkanes to measure grass intake.  Every day, some horses ate an amount of grass equivalent to 5% of their body weight. Some individuals increased their body weight by 4% a week.

“So you can see that grass easily provides horses with excess calories,” she said “ leading to gradual accumulation of fat. Excess calories over time equals fat. Not all fat is the same.”

She explained that research had shown that some adipose (fat) tissue is metabolically active. The fat cells (adipocytes) release numerous biologically active substances (adipocytokines), which affect glucose and fat metabolism. When present in excess they can lead to insulin resistance, which in turn can result in laminitis.

“The slow insidious eating of excess grass over years is the problem; not the grass they ate today. People get insulin resistance and diabetes because they have been on a bad diet for years, not because they ate a doughnut today!”

What can you do to prevent laminitis associated with insulin resistance?

First you need to reduce the fat. Give thirty minutes exercise daily with a heart rate of 80 beasts per minute. (“Turnout in the paddock is not enough” she says). Accept that the horse or pony will lose weight (fat) over the winter.  Indeed encourage him to do so by using lightweight rugs only - so that he burns fat to keep warm.

Do not starve the horse. Maintain the bulk intake (at 2.5% of body weight) - otherwise he will be prone to developing stereotypies or gastric ulcers. But reduce the calorie intake - soak the hay for 12hours or feed oat or barley straw.

Make sure horses do not get too much grass. Consider using a muzzle; increase the number of horses (and /or cattle and sheep) on the pasture. It’s important to feed a balanced diet.  Make sure the horses receive adequate proteins, minerals and vitamins by feeding a low calorie commercial feed balancer.

The solution is to reduce obesity, ensure nutrition is optimal, and increase exercise.

Monitoring respiratory disease

Researchers at the University of Glasgow have developed  two new non-invasive methods of monitoring respiratory disease in horses.

The number of times a horse coughs provides a good indication of respiratory inflammation - the more inflammation, the more the horse coughs. But it is often not practical, or cost-effective, for someone to physically count the number of times a horse coughs over an extended period.

The research team, led by Professor Sandy Love,  has developed a technique that uses a digital audio recorder attached to the head collar to monitor cough frequency over a long period of time.

In a study to test the value of the technique, the researchers compared audio recordings, each lasting one hour,  with simultaneous video recordings. A total of nine recordings were collected from seven stabled horses .

The  graph of the  audio file could then be examined to identify coughs. Not only was this a rapid process - a  recording lasting one hour could be analysed within three minutes - the technique was also found to be very accurate.

When they compared the audio and video recordings the researchers found that every cough was correctly identified, and no extraneous noises, such as foot stamping,  were mistaken for coughs.
They point out that the speed of the  analysis could be increased further by using  computer software to automate the analysis.

The project also led to the development of a simple device that could be attached to the horse’s head collar to  collect expired moisture. It was used to study the constituents of exhaled breath to see if any could be used as indicators of respiratory inflammation.

The researchers found that the most useful indicator was the pH of the liquid condensed from the expired breath. There was trend toward a reduced pH (acidification) in horses with lower airway inflammation.

The concentration of gases such as carbon monoxide, nitric oxide and ethane was also measured, but the researchers found no correlation between these substances and inflammation in the respiratory tract.

The work was made possible by funding from The Horse Trust . Paul Jepson, Chief Executive and Veterinary Director of The Horse Trust said, “ "We are delighted that the research we have funded has led to new, non-invasive ways of monitoring respiratory inflammation in horses. These techniques could have a major impact on horse welfare by improving the diagnosis and treatment of this common condition.”

Bladder stone laser treatment

Normal equine urine contains many calcium carbonate crystals. Despite that, it is not common for stones (“calculi”) to form in the urinary tract of horses. They are most often seen in the bladder (“urocystoliths”) or urethra (urethroliths”).

It is possible to remove them surgically, which may require general anaesthesia and carry the risk of complications - in particular peritonitis. Other methods include disrupting the calculi with shock waves or laser.

Researchers at the Virginia-Maryland Regional College of Veterinary Medicine and the School of Veterinary Medicine at the University of California, Davis have described a minimally invasive technique using a laser to break up the urinary calculi.

An optical fibre is passed through the biopsy channel of the endoscope. This is used to direct the beam from the laser onto the bladder stone. The procedure can be carried out without the need for epidural or local analgesia.

The surgeon sweeps the fibre across the surface of the stone to produce a crater or groove until eventually a fragment breaks off. This process is repeated as many times as necessary until the remaining pieces of urolith are small enough to pass out through the urethra.

Larger fragments are removed by grasping them with a wire basket passed through the endoscope. Smaller fragments are flushed out.

The technique was successful for removing all uroliths and fragments in five of a series of seven cases. The authors concluded that laser lithotripsy combined with lavage and retrieval of larger fragments using the endoscope was a safe procedure. They suggest that if no progress is made within the first 30 minutes the case will have to be managed by other means.

Read more at Equine Science Update

Equine atypical myopathy - possible cause found

Researchers at the University of Bern, Switzerland, have identified a possible cause for the often fatal disease atypical myopathy. They found evidence to implicate a toxin produced by the bacterium Clostridium sordellii. The toxin is known to cause severe muscle damage in mice.

The researchers examined heart and skeletal muscle samples from horses affected with Atypical Myopathy using transmission electron microscopy. They found that the changes that were present were similar to those found in mice affected by the toxin.

They also used immuno histochemistry staining techniques to show that the lethal toxin of Clostridium sordellii was present in the muscle fibres of affected animals. Antibodies from horses with Equine Atypical Myopathy and antibodies to the lethal toxin of Clostridium sordellii both bound to muscle fibres taken from horses affected with EAM.

In contrast, neither of the antibodies attached to normal horse muscle fibres or to muscle fibres taken from horses with other types of muscle disease.

The scientists concluded that there is evidence that the lethal toxin of Clostridium sordellii plays a role, either as a trigger, or even as a lethal factor, in Atypical Myopathy.

Read more at Equine Science Update.co.uk

Urine DNA profiling

Scientists will soon be able to use DNA profiling techniques to confirm the identity of racehorses that have tested positive to drugs.

Such a test would dispel any doubt about sample substitution and confirm that a sample did in fact come from a particular horse, helping to either confirm the identity of horses returning positive drug samples, or exonerating horse and trainer.

The report “DNA Profiling of Horse Urine Samples to Confirm Donor Identity” resulted from studies carried out by Paula Hawthorne and colleagues at the University of Queensland, and was funded by the Australian Government's Rural Industries Research and Development Corporation (RIRDC). The research team tested various techniques for DNA profiling on seven urine samples and compared the results with those from hair samples taken from the same horses.

They found that storage time and temperature had a significant effect on the success of the DNA profiling. Urine could be stored at 4°C for no more than two days (or frozen at -20°C or -80°C) before processing. Samples stored at 4°C for a week or more yielded no profiles.

The most successful technique, a commercially available test, allowed them to identify all twelve microsatellites, in four urine samples - all from male animals. As only seven samples were examined overall, it was not possible to tell whether that was a coincidence, or whether it really is more difficult to extract DNA from mare’s urine.

All DNA profiles from the urine samples matched those from the hair taken from the same horses.

There is still more work to do - for example, the researchers point out that drugs in the urine may interfere with DNA profiling. So once the best method of DNA profiling has been established, further tests will be required to assess whether the results are affected by drugs likely to be found in the urine.

However, the authors of the report suggest that once the optimum method has been finalised it should not take long to integrate it into existing procedures of racing drug-testing laboratories.

The full report is available for purchase or free download. See:
https://rirdc.infoservices.com.au/items/09-076

Risk of Atypical Myopathy cases this spring.

“There seems to be an increased risk of cases of Atypical Myopathy during the spring, when the disease has occurred during the previous fall” warns Dr Domonique Votion, of the University of Liege.

In the last few months of 2009, Western Europe experienced the largest ever series of cases of the disease, according to the Atypical Myopathy Alert Group (AMAG).

No less than 371 cases were notified to the AMAG. Of those horses, 265 died, giving a survival rate of just 22%. Most cases were reported in France (124) Germany (92), and Belgium (64).
Thirty-five cases were identified in the UK.

Horses with Atypical Myopathy suffer from severe, generalised weakness. They are often unable to get to their feet, or only do so with difficulty. If they are still able to walk, they do so with a stiff gait - especially of the hindquarters. Muscle tremors and generalised or patchy sweating may be seen.

Affected animals have elevated heart rates. They often have increased respiratory rates, with difficulty on expiration. The rectal temperature is usually below normal. Dark brown colouration of the urine is characteristic.

Despite the severity of the signs, horses often still seem keen to eat and will try to grasp hay that is held close to their mouth.

Often the first sign of disease is stiffness, especially of the hindquarters. However, it is not unusual for severely affected cases to be found dead on the pasture with no previous sign of illness.

For more details about the Atypical Myopathy and the Atypical Myopathy Alert Group see:

http://www.myopathieatypique.be

Disease surveillance report

The latest equine disease surveillance report published jointly by the UK Government’s Department for environment food and rural affairs (Defra), Animal Health Trust (AHT) and the British Equine Veterinary Association (BEVA), is now available. The report covering the period October - December 2009 has been uploaded recently to the Animal Health Trust website.

The Defra/AHT/BEVA equine quarterly disease surveillance report collates equine disease data arising from multiple diagnostic laboratories and veterinary practices throughout the United Kingdom. The current edition includes data from 30 laboratories and offers a unique insight into equine disease occurrence in the UK.

A form is available on the AHT website for registration to receive reports free of charge, via e-mail, on a quarterly basis.

See:

http://www.aht.org.uk/equine_disease.html

EMS research: help needed

Do you have a horse or pony with Equine Metabolic Syndrome? If so, scientists at the University of Minnesota's Equine Genetics and Genomics Laboratory would like to hear from you.

EMS is characterized by three main features: obesity or regional accumulation of fat (particularly in the crest or over the rump), insulin resistance and laminitis.

Some horses, often considered to be "easy keepers" by their owners, are more at risk of EMS than others. It is likely that the genetic make-up of the horse affects its susceptibility to the condition.

The aim of the study is to better understand the role in EMS of factors such as breed, gender, age, environment (diet and exercise) and genetics. To achieve this, the researchers need to collect data from as many horses with EMS as possible. So, they are keen to encourage horse owners and their veterinarians to get involved.

If you are interested in taking part in the Equine Metabolic Syndrome research project, the first step is to complete a short online survey. Within about one month, if your horse is considered suitable for the project, you will be asked to complete a second survey. This will ask for further information about the horse and about another horse, unaffected by EMS, that lives on the same property. This horse will serve as a "control". Ideally the control horse should be of similar breed and age, have no history of laminitis, not be overweight and show no signs of Cushing's syndrome (delayed shedding, increased drinking/urination).

The third step is to submit a blood sample to the laboratory, for biochemical analysis and DNA evaluation.

To identify the underlying genetic susceptibility to EMS, the scientists will compare genetic markers between horses with and without EMS. The genetic differences that are highly correlated to having EMS can be used as genetic markers for the disease.

The long-term goal is to use these EMS genetic markers to detect horses susceptible to EMS and laminitis before they have clinical signs. It may then be possible to change the management of susceptible animals to reduce the risk of them developing disease.


For more details about the study

http://www.cvm.umn.edu/equinegenetics/ems/research/index.htm

Rapid ringworm diagnosis

Scientists in South Korea have described a rapid method for diagnosing ringworm (dermatophytosis.)

Fungal culture is the “gold standard” method for identifying the species of dermatophyte involved, based on the colony characteristics and microscopic appearance. It is accurate but time consuming. Samples may have to be cultured for up to three weeks before the organism can be identified.

It’s not necessary to know the species before starting treatment. Indeed, to prevent the spread of infection, treatment is usually started pending the results of laboratory investigations.

However, there are occasions when it may be useful to know the identity of the dermatophyte involved, as it may help to identify the source of the outbreak. For example Trichophyton mentagrophytes can be found in soil and be carried by rodents.

Researchers at the Colleges of Veterinary Medicine at Seoul National University and Konkuk University compared a rapid molecular PCR assay with conventional fungal culture for diagnosing ringworm.

They found that the PCR analysis of the fungal DNA was superior to traditional fungal culture for diagnosing dermatophyte infection, “ in terms of sensitivity, specificity and particularly rapidity.”

Read more at www.equinescienceupdate.co.uk/rmmdd.htm

Exercise and pregnant mares

In humans, moderate exercise in pregnancy seems to do no harm and may help limit excessive weight gain and maintain fitness for the birth. What about horses? Many pregnant mares are ridden and subject to moderate training up to the later stages of pregnancy.

A research team from the University of Maine and the Equine Science Center, Rutgers University, New Jersey compared the response of pregnant and non-pregnant mares to a graded exercise test.

Six unfit standardbred mares were assessed when nine months pregnant and again eight months later after weaning. The exercise test was carried out on a treadmill inclined at 6%. The speed increased in steps of one minute each at 4m/s, 6m/s and 7m/s.

At each stage of the graduated exercise test, mares had lower heart rates when pregnant than after weaning. Plasma lactate concentrations rose less in response to exercise when mares were pregnant than when they were not. The researchers speculate that this might be due to greater cardiovascular efficiency during pregnancy.

Resting plasma cortisol levels were lower during pregnancy than when the mares were not pregnant.

When exercised, pregnant mares showed no increase in cortisol levels. In contrast, when they were not in-foal, the mares showed a normal increase in plasma cortisol during and after the exercise test.

Neither did exercise have an effect on foetal heart rate. This suggests that the unborn foal is not stressed by the mare undertaking moderate exercise.

The researchers conclude: “these data suggest that pregnant mares benefit from greater cardiovascular efficiency during pregnancy. They should be able to perform limited moderate exercise without any major deleterious effects on their unborn foals or themselves during late gestation.”


Read more...

Tick-borne disease in Danish horses

Tick-borne infections are common in Danish horses. A survey published in Acta Veterinaria Scandinavica showed that many Danish horses carry antibodies to Borrelia burgdorferi sensu lato (the group of Borrelia species known to cause Lyme disease) and Anaplasma phagocytophilium (the cause of equine granulocytic anaplasmosis).

The study, overseen by Dr Anders M Bojesen of the Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Denmark aimed to evaluate the seroprevalence of B. burgdorferi s. l. and A. phagocytophilium in Danish horses.

Overall, 29.0% horses were seropositive for B. burgdorferi s. l. and 22.3% were seropositive for A. phagocytophilium. This was a higher proportion than had been found in previous studies in neighbouring countries.

There was no significant correlation between risk factors investigated, including breed, gender, age, use and housing and the occurrence of antibodies against B. burgdorferi s. l.

However the researchers did find that older horses were more likely to have been infected with A. phagocytophilium. Compared with horses aged between 1-4 years old, those aged 11-20 years were 2.3 times more likely to be seropositive for A. phagocytophilium, and horses over 21 years old were 3.3 times more likely to be seropositive.

Horses seropositive for B. burgdorferi s. l. were likely to be seropositive for A. phagocytophilium and vice versa.

The researchers conclude “these findings warrant further attention to these infections in horses particularly with regard to improved means for detection of active infections, which may contribute to a better understanding of these diseases and their impact on horse behaviour and welfare.”

More details...

New equine respiratory condition described

Danish Researchers have identified a new cause of respiratory disease in horses. They found the bacterium Stenotrophomonas maltophilia in samples collected from horses with chronic lower airway disease.

Stenotrophomonas maltophilia, a Gram-negative bacterium, has been found increasingly in human medicine, especially in patients with impaired immune systems. Until recently the organism has been recorded only rarely in animals.

In a paper to be published in The Veterinary Journal, Lotte Winther, a PhD student in the Department of Large Animal Sciences at the University of Copenhagen, and colleagues present data from seven horses with respiratory disease associated with S. maltophilia infection.

All cases had a history of chronic coughing. Endoscopic examination revealed copious mucopurulent exudate in the lower trachea. Culture of the tracheal exudate produced grey, slow-growing colonies, which were identified as S. maltophilia by both culture and DNA testing.

Many antibiotics commonly used to treat equine respiratory infections were not effective against S. maltophilia.

The findings suggest that S. maltophilia can act as a respiratory pathogen. The researchers advise that the organism be included in the differential diagnosis of horses with respiratory disease associated with copious mucopurulent exudate.

Read more...

TEST TO PREVENT UNNECESSARY FOAL DEATHS LAUNCHED

A new diagnostic test, which gives breeders the ability to eradicate Foal Immunodeficiency Syndrome, was launched on 1 February by UK scientists.

Foal Immunodeficiency Syndrome (FIS), a genetic disorder which is known to affect Fell and Dales ponies, causes foals to become anaemic and prone to opportunistic infections. Sadly, any foal born with the syndrome will not survive.

The DNA test, which costs £40, will not only identify foals which have the fatal condition but will highlight adult ponies who are carriers of the genetic trait which causes the syndrome. Affected foals will be prevented by avoiding breeding a carrier mare with a carrier stallion.

Owners and breeders who wish to find out the genetic status of their ponies can arrange for a simple pulled mane or tail hair sample to be taken by a vet and submitted to the Animal Health Trust. The Fell Pony or Dales Pony Societies will supply sample bags for submission on request.

Dr. June Swinburne of the AHT, who led the research team, said: “The DNA test gives owners and breeders the power to overcome this devastating illness. It enables them to make informed decisions about which ponies to breed. We have already had samples submitted by HM The Queen from her own breeding stock of Fell ponies. I’d urge any breeders of Fell or Dales ponies to submit samples in order to arm themselves with the facts they need to prevent the birth of affected foals and thereby avoid this distressing condition.”

For more information on testing, owners should contact the Fell or Dales Pony Societies.
Alternatively visit the AHT website http://www.aht.org.uk/genetics_fis.html or email FIStesting@aht.org.uk

Ivermectin for foal deworming warning

Ivermectin should not be the drug of choice for controlling Parascaris equorum (large roundworm) in foals a recent study warns.

Dr Eva Osterman-Lind and Dr Dan Cristensson of the National Veterinary Institute, Uppsala, Sweden, investigated the occurrence of Parascaris equorum infection on nine stud farms in Sweden and assessed the efficacy of three commonly used dewormers.

They found that ivermectin had very little, or no, effect on the output of ascarid eggs.

“The most striking result from this study was that in five studs out of six, ivermectin failed to suppress the faecal output of P. equorum eggs” Osterman-Lind and Cristensson report in the journal Acta Vet Scandinavica. “Ivermectin resistance is now a widespread problem in Swedish stud farms.”

Read more...

How common are wobblers?

Cervical vertebral stenotic myelopathy (CVSM) is an important disease of Thoroughbred horses in which compression of the spinal cord in the neck leads to incoordinated gait. Affected horses are often described as “wobblers”.

But how common is the condition? Researchers at the University of Glasgow studied records from four breeding establishments - three European Thoroughbred stud farms (936 foals) and one farm in USA (353 foals) - over a 7 year period.

During that time there were 13 cases of Type 1 CVSM, (dynamic stenosis); 5 horses with Type 2 CVSM (static stenosis) and 5 horses in which the Type could not be determined. Overall, 1.3% of the animals were found to be affected.

The average age at which signs of the condition became apparent differed. Horses affected with dynamic stenosis were noticed at a younger age than were those with static stenosis. Type 1 (dynamic stenosis) was diagnosed typically in yearlings (Mean 433days old - about 1y 2 months.) Horses affected with the stenotic compression were diagnosed later - (mean 1188d -about 3years 3 months)

The researchers also found that male horses were significantly more likely to be affected (17 male to 6 female), which agreed with previous studies.

“CVSM is an important disease of Thoroughbred horses and leads to wastage in the thoroughbred industry through the inability to race and the loss of affected horses” the report's authors conclude.

They suggest that “further investigations of the prevalence of CVSM in populations of thoroughbreds and other breeds and determination of risk factors for the disease are warranted.”

More details...

Genetic Test for ‘Speed Gene’ in Thoroughbred Horses

Researchers have identified a gene that can predict the type of work that is most appropriate for an individual Thoroughbred racehorse.

The work, led by Dr Emmeline Hill at University College Dublin, was published in the Public Library of Science Journal, PLoS ONE.

The MSTN gene is responsible for muscle mass development. At a specific point in the gene, the code can contain either the letter C or the letter T. As each individual has two copies of the gene—one inherited from the dam, one from the sire—there are three possible combinations of the letters: C:C, C:T or T:T.

The researchers found that C:C horses were suited to fast, short-distance races; C:T horses competed favorably in middle-distance races; and T:T horses had greater stamina.

The findings were independently validated in a re-sampled group of 62 unrelated elite (Group and Listed race winners) Thoroughbreds and in another group of 37 elite racehorses.

Following the success of the research program, Dr Hill and Mr Jim Bolger, the renowned Irish racehorse trainer and breeder, co-founded a company, Equinome, in 2009 to commercialize the test.

Dr Hill says “Using the Equinome Speed Gene test, a world first in equine genetics, it will now be possible to definitively know a horse’s genetic type within weeks of a sample being taken, thus reducing much of the uncertainty that has been typically involved in selection, training and breeding decisions.”

“Racehorse owners and trainers around the world will be able to identify if a horse is ideally suited to racing over short, middle or middle-to-long distances. With this information, they can then optimize their purchasing and training decisions and better target suitable races for their horses. Breeders, stallion managers and bloodstock agents will also be able to use the test to make more precise selection and breeding decisions to maximize the genetic potential and commercial value of their horses.”

Dr Hill will formally launch Equinome and the Equinome Speed Gene test at 2pm on January 29th at the Irish Thoroughbred Breeders Association Expo 2010 in a seminar entitled Cracking the code: The Speed Gene revealed.


Read more at EquineScienceUpdate.co.uk

For more information about Equinome

Oxytocin promotes placental expulsion

Retention of the fetal membranes is a common post-foaling complication. It is of particular concern in heavy draft breeds, which seem especially likely to develop laminitis if expulsion of the membranes is delayed.

A Japanese study, led by Dr Mitsuo Ishii, found that hourly injections of oxytocin after foaling was an effective way of inducing placental expulsion.

"I recommend that for heavy draft mares, 50iu of oxytocin should be administered from one
hour after foaling and continued at one hour intervals until expulsion of the placenta" Dr Ishii says. " We usually don't remove the placenta manually until 8 hours after foaling."

See more details at equinescienceupdate.co.uk

Sarcoid treatment breakthrough

The battle against sarcoids is forging ahead. Researchers in Scotland have succeeded in killing equine sarcoid cells using a technique known as gene silencing. They are now hoping to obtain funding for clinical trials using the new technique, which could result in a more effective, non-toxic treatment for sarcoids.

Sarcoids are the most common type of tumour found in horses. They are caused by infection with the Bovine Papillomavirus (BPV). The response to treatment is variable, and if treatment fails the sarcoids will often come back with a vengeance.

Recent research, funded by The Horse Trust, offers a potential ray of hope for owners of horses affected by sarcoids. The work was published in the journal Virus Research.

The research, led by Professor Lubna Nasir of the University of Glasgow, found that by inhibiting the activity of a particular viral protein within sarcoid cells, the amount of viral DNA in the cells reduced. This led to a reduction in the growth of the sarcoid cells and caused the cell to die by “Programmed cell-death” (PCD). The researchers believe that PCD occurs because the sarcoid cells become reliant on the virus.

"This could potentially be a major breakthrough in the treatment of sarcoids," said Professor Lubna Nasir. "We are now seeking funding to use this technique in clinical trials on horses that have sarcoids."

"One of the challenges with gene silencing is administering it within clinical setting - as you need to get molecules into every cell. As sarcoids are on the surface of a horse, we think administration should be relatively easy - potentially by injecting or applying a cream to the sarcoid," said Professor Nasir. "If we are able to successfully develop this technique it would be a non-toxic and easy to administer treatment for horses affected by this distressing condition."

See www.equinescienceupdate.co.uk for more details.

Treating piroplasmosis

Research brings hope for horses with piroplasmosis. A drug used to treat protozoal infections in cattle has been shown to be effective against one form of the disease in horses when used at relatively high doses.

Piroplasmosis in horses is known to be caused by two blood-borne parasites, Babesia (Theileria) equi and Babesia caballi. The organisms infect the red blood cells and cause fever, anemia and jaundice.

Infected horses may remain carriers of the infection after recovering from the initial signs of disease. Such horses can transmit the disease even though the organisms can no longer be found in blood smears.

Now researchers at the Agricultural Research Service Animal Disease Research Unit in Pullman, Washington, led by Dr Don Knowles, have found that relatively high doses of imidocarb dipropionate are effective for treating horses infected with Babesia caballi.

Read the full story at equinescienceupdate.co.uk

Test for Fell Pony syndrome

Scientists have developed a test for the gene responsible for Foal Immunodeficiency Syndrome (FIS).

FIS is more often known as Fell Pony Syndrome after the breed most commonly affected. However, the disease is not confined to the Fell Pony, and has been reported in the Dales Pony as well.

Affected foals become ill when they are a few weeks old. Signs include loss of condition, diarrhea, coughing and weight loss. As the condition progresses, they develop anemia, immune dysfunction, and wasting.

FIS is always fatal. Affected foals die or are euthanized, usually before reaching three months of age.

Researchers at New market’s Animal Health Trust (AHT) and Liverpool University have announced that a DNA-based test that should be available in February 2010.

Read the full story at equinescienceupdate.co.uk

Does work cause stereotypies?

Does the type of work that horses do make them more or less likely to adopt stereotypic behaviour? Recent studies in France suggest it could do.

Stereotypies are abnormal repetitive behaviours with no apparent function. They are sometimes referred to as stable vices. Examples include wind sucking, crib biting and head tossing.

Researchers at the Université de Rennes 1, led by Dr Martine Hausberger, observed horses’ behaviour and related it to the type of work they performed.

Seventy-six French Saddlebred horses were divided into six groups according to their work: eventing; show jumping; advanced riding school; dressage; high school and voltige (a mixture of acrobatics and gymnastics on horseback.) All horses worked for only one hour a day and spent the remaining 23 hours in their stable.

The proportion of horses in each work group showing stereotypies was similar (between 81-100%). However, different types of work appeared to be associated with different stereotypies.

Dressage and high school horses were most likely to show stereotypic behaviours. Some of them showed more than one abnormal behaviour pattern. They were also more likely to display the more serious abnormalities such as cribbing, wind sucking and head tossing and nodding.

For more details see equinescienceupdate.co.uk/wsbd.htm

Scientists to study effect of exercise on laminitis.

The Laminitis Trust has awarded a grant of £134,425 to the Royal Veterinary College and the Laminitis Consortium to investigate the effects of exercise on horses and ponies that are predisposed to pasture-associated laminitis.

Lead investigator, Dr Menzies-Gow, explains: “This project will in part investigate whether exercise can reduce the level of chronic inflammation in laminitis-prone animals, which may then prove to be a simple and practical way of reducing the risk of future bouts of disease in susceptible animals.”

The grant commences in January 2010 and will run over two years. The Laminitis Consortium will provide regular updates on progress.

See equinescienceupdate.co.uk for more details...

3D study of neck anatomy

Wobbler syndrome (Cervical Vertebral Malformation, CVM) is a common condition of Thoroughbred horses. Affected horses have a characteristic “wobbly” gait, caused by compression of the spinal cord.

In some cases, the signs of Wobbler Syndrome (Cervical Vertebral Malformation, CVM) have been linked to arthritic changes in the cervical articular process joints. These are the joints between adjacent vertebrae in the neck. They can become inflamed, which can result in soft tissue swelling, thickening of the joint capsule and new bone formation. The joints lie close to the spinal cord, so any increase in their size is a cause for concern.

Some “wobblers” have marked bony and soft tissue swelling around the joints. But does an increase in fluid in these joints result in spinal cord compression, even if no other bony of soft tissue changes are present? If so, it might be possible to prevent the disease progressing by detecting and treating the inflammation at an early stage.

Holly Claridge, working at the Royal Veterinary College, conducted a study using Computed Tomography to examine the structure of the horse’s neck. She found that the joints these joints do indeed extend towards, but do not actually touch, the spinal cord.

So, unless soft tissue or bony changes are also present, it seems unlikely that inflammation or swelling of these joints causes spinal cord compression.

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Inner secrets of Rhodococcus equi

Work to understand the genetic structure of Rhodococcus equi may lead to new measures to control disease in foals. Understanding the complex mechanisms used by the bacteria to cause disease may reveal the microbe’s “Achilles heel” that could be targeted by vaccines and drugs.

“Among the virulence factors we have identified, we have found one in particular that we think might be a good target for a vaccine” says Professor Jose Vazquez-Boland of Edinburgh University. Pathogenic strains of the bacteria have long processes or “pili”, with which they attach to the host cells.

“We identified the genes responsible and produced antibodies against them.” These antibodies prevent the bacteria attaching to the cells and so prevent infection getting established. So this would be a good candidate for a vaccine.

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How effective is your deworming program?

The importance of knowing that your worm control program is effective was emphasized by Professor Jacqui Matthews when she spoke at the Thoroughbred Racing and Breeding Seminar at Cheltenham.

The cyathostomins (small strongyles) are the most important group of intestinal parasites of the horse - both numerically, and through their ability to cause disease. They are becoming increasingly difficult to control as they develop resistance to the drugs used against them.

“Not enough of us are thinking about the level of burden individual horses have in terms of giving them worm treatments. When we treat horses with viral disease we don’t usually treat the whole group. And we don’t do that with antibiotics.” So why not just deworm the horses that need it?

In the spring and summer, fecal egg counts can be used to identify which horses to treat. But encysted worms in the gut wall in winter cannot be detected with fecal egg counts. So we also need to detect horses with high larval counts.

Prof Matthews’ team have been working to develop a blood test to measure the antibody response to proteins released by these encysted stages within the gut wall.

Detecting resistance is also vital. The research team at Edinburgh has just received funding to update and refine the fecal egg count reduction test (FECRT) that is used to detect resistance to anthelmintics. Hopefully this will lead to better thresholds for resistance levels to individual drugs.

They are looking for studs with large numbers of young horses to help in the research. The project will involve a questionnaire, treatment with ivermectin and a FECRT, which will be provided free of charge.

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Thoroughbred Racing and Breeding Seminar

A panel of top equine researchers and veterinarians covered a range of subjects at the Thoroughbred Racing and Breeders Seminar. The event, now in its ninth year, was supported by the Horserace Betting Levy Board, Intervet Schering Plough Animal Health and cheltenham Racecourse.

The latest research on a variety of topics was presented.

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Immunodeficiency/anaemia in a Dales pony.

Fell ponies are not the only breed to be affected with an immunodeficiency / anaemia syndrome.
Now a similar condition has been reported in a Dales pony

The report’s authors, based at the Animal Health Trust in Newmarket and the Liverpool Vet School, describe a female Dales pony foal with marked anaemia, diarrhoea and pneumonia, that failed to respond to treatment. The foal was euthanased at nearly 6 weeks of age. Post mortem signs were typical of Fell pony syndrome.

The scientists, who are already studying Fell pony syndrome, are now widening their scope to pay close attention to the Dales pony as well.

They suggest that, although there are other causes of anaemia in foals, the anaemia/immunodeficiency syndrome should be considered in any young foal with marked anaemia (PCV < 20%) and relevant clinical signs.

They urge owners, breeders and veterinarians dealing with Dales ponies to be aware of the disease, and ask that any suspect cases be referred to the research team at the Animal Health Trust or the Liverpool University Veterinary School.

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