Thursday, June 27, 2013

Hendra Virus Research Program

The impact of human behaviour on the spread of the Hendra virus is being studied to help develop control strategies.

HHALTER (Horse owners and Hendra Virus: A Longitudinal cohort study To Evaluate Risk) is a three-year project funded by the Commonwealth of Australia, the State of New South Wales, the State of Queensland and the Rural Industries Research and Development Corporation under the National Hendra Virus Research Program.

The project aims to look at how humans respond to the threat of Hendra virus, and what can be done by horse owners and others in regular contact with horses  to reduce the chance of transmission from flying foxes to horses and then to humans.

The researchers hope to attract more than 2500 people, horse owners and people in regular contact with horses, from all sectors of the equine industry throughout Australia.  It is not only residents of areas where Hendra virus cases have already occurred that are sought for the study. People living in parts of Australia  that have not seen cases of the disease are encouraged to take part as well.

Participants are asked to complete five surveys conducted at six-month intervals. The surveys investigate the factors influencing people’s awareness about the risks from Hendra virus and their use of prevention strategies.

Dr Kate Sawford,  Research Associate in Animal Health Biosecurity at the University of Sydney, said: “The combination of a high human death rate, no cure and no human vaccine means that Hendra virus is a frightening disease. An outbreak of Hendra virus on a property cannot only impact people’s health, but also be financially, professionally, emotionally and psychologically damaging.

The first survey with horse owners and horse care providers has now been completed. This focused on Hendra virus risk awareness, perceptions and knowledge, with large sections dedicated to practices employed on properties to limit the risk from the virus  and attitudes to vaccination.

Another four surveys with horse owners and horse care providers will be conducted over the next two years.

To participate in the research project or find out more information visit

A brief summary of some preliminary findings is available in the first HHALTER Project Research Newsletter.

Tuesday, June 25, 2013

Tick paralysis high death rate

Tick paralysis is more likely to be fatal in horses than in small animals according to recent research.

Findings presented at the Australian Veterinary Association conference showed that 26% of affected horses died and 35% of surviving horses developed one or more complications.

Tick paralysis,is caused by the Australian paralysis tick Ixodes holocyclus, and has been known to affect horses since the early days of Australian settlement.

Dr Mick Ruppin, one of the co-authors of the study explained: “The paralysis tick is found predominantly along the east coast of Australia, in high rainfall areas. Our study was a retrospective analysis of cases treated at our practice on the east coast of Queensland, over the last ten years, as well as cases treated at other practices along the east coast over the last five years. A total of 103 cases were analysed.

“The number of paralysis ticks required to paralyse a horse is unknown but our study included cases where large horses with only one to two ticks were paralysed and unable to stand. Horses of any age and size can be affected by tick paralysis” Dr Ruppin added.

“The mortality rate of 26% in horses is much higher than the mortality rate in small animals which is around five per cent.

Dr Ruppin said that higher mortality rates in horses could be due to a range of factors including horses being badly affected before vets are called; difficulties associated with nursing a recumbent horse; difficulties with owners needing to deliver the bulk of nursing care and lack of information to veterinarians treating the disease in horses.
“In our study, 26 % of the horses died and of the surviving horses, 35% developed one or more complications including pressure sores, corneal ulcers, pneumonia and sepsis.

“Given the difficulties associated with treating tick paralysis in horses, prevention is the best option for horse owners,” he said.


Sunday, June 23, 2013

Sycamore linked to Atypical Myopathy

 Toxic seeds of the sycamore (Acer pseudoplatanus) are the likely cause of Atypical Myopathy (AM)

Atypical Myopathy is a highly fatal muscle disease of horses in the UK and Northern Europe. In ten years, approximately twenty European countries have reported the disease. Incidences tend to occur repeatedly in the autumn and in the spring following large autumnal outbreaks. Horses that develop AM are usually kept in sparse pastures with an accumulation of dead leaves, dead wood and trees in or around the pasture and are often not fed any supplementary hay or feed.

A very similar disorder, Seasonal Pasture Myopathy (SPM), which occurs in Midwestern USA and Eastern Canada, is now known to be caused by a toxin (hypoglycin A), contained in seeds from the box elder tree.

The European research team, led by Dominic Votion, of the University of Liege, studied 17 horses from Belgium, Germany and The Netherlands, suffering from Atypical Myopathy. They found high concentrations of methylenecyclopropyl acetic acid (MCPA), a toxic metabolite of hypoglycin A, in the serum of all affected horses.

The pastures of 12 of the horses were visited by experienced botanists and Acer pseudoplatanus, the sycamore maple, was found to be present in every case. This was the only tree common to all visited pastures. Acer negundo, the box maple, was not present on any of the farms on which atypical myopathy occured.

Researchers believe hypoglycin A is the likely cause of both AM in Europe and SPM in North America. The sycamore and the box elder are known to produce seeds containing hypoglycin A and the pastures of the afflicted horses in Europe and the USA were surrounded by these trees.
in European horses, according a new study.


Sunday, June 16, 2013

More help needed for saddle slip study

Horse riders are being asked to help with an important research project looking into the interaction between horse, saddle and rider.

Researchers, led by Dr Sue Dyson, Head of Clinical Orthopaedics at the Centre for Equine Studies at the Animal Health Trust, are running a detailed study to find out how the horse, rider and saddle influence each other. In particular they want to understand better why some saddles persistently slip to one side in some horses.

Saddle slip in sports horses is a well-recognised problem that can occur for a variety of reasons, including asymmetry in the shape of the horse’s back, riders sitting crookedly and ill-fitting saddles.

Participants in the study simply need to complete an anonymous online questionnaire. In doing so the researchers say that they will be helping to protect and improve the future health, welfare and longevity of the ridden horse.

Preliminary invevstigations have looked at just over 700 riders, but for a more accurate picture the research team would like to include more than 1000 people.

“We are urging all riders, whatever their level or ability, to help by completing the questionnaire,” said Line Greve, a PhD student at the Centre for Equine Studies.

“Saddle slip is a problem seen in all sorts of horses and ponies and can contribute to back pain and thus impaired performance,” she explains. “Research suggests that 25% of British dressage horses have a history of back-related problems and subsequent reduced performance.”

The online questionnaire should take no more than 15 minutes to complete. The questions cover saddle types, use and maintenance as well as rider experience and training, and any previous equine lameness or back-related problems.

Participants will remain anonymous and the results will be presented at the Saddle Research Trust Conference in 2014.

To take part in the study, follow this link to the questionnaire

Thursday, June 06, 2013

Sperm from dead horses

The unexpected death of a prize stallion need not necessarily spell the end of his breeding career.  Obviously many breeding stallions will have had semen frozen and stored for future use. But what if that has not been done?

Or you may have a promising colt and be unable to decide between keeping him entire for breeding, or having him castrated. The answer may lie in cryopreservation of epididymal sperm.

It is now possible to salvage sperm from the tail of the epididymis – the long convoluted tube into which the sperm pass after being produced in the testis. As well as acting as a reservoir for the sperm, the epididymis provides an environment in which they can mature and become able to fertilise oocytes.

The procedure for harvesting and freezing the sperm is not widely available. So what can be done if the laboratory is a long way away? Will  delay adversely affect the viability of the sperm?

Research in the Department of Physiology at the University of Murcia in Spain suggests that spermatozoa stored in the epididymis for up to 96 hours at 4º C can be cryopreserved successfully and still retain the ability  to fertilise. 

In work published in the journal Animal Reproduction  Science, Luis Vieira and others  studied the viability of sperm stored  in the epididymis obtained from castrated horses.

Testes were transported to the laboratory in insulated  containers at ambient temperature within one hour of castration. At the laboratory, the epididymides were washed in physiological saline, wrapped in foil to prevent them drying out, and stored in a refrigerator at  4º C for up to 96 hours.

The scientists harvested the sperm by introducing a syringe and needle into the vas deferens and flushing out the epididymal contents. The sperm were mixed with extender before being frozen and stored in liquid nitrogen.

Measurements  of viability of sperm in the epididymal fluid were made at various stages in the procedure.

Viability was good (85%) if the sperm were harvested on the day of castration , and remained at more than 80% until 72 hours after castration. Sperm stored for 96 hours before harvesting were significantly less viable.

After dilution in the freezing media and storage at 4º C for 30 minutes, viability remained good for sperm harvested within 48 hours of castration.  Viability was lower in sperm collected 72 and 96 hours after castration.

On the other hand, time (up to 96 hrs) from castration to harvesting did not appear to affect the viability after freezing and thawing, which was almost 35%.

Other measures of sperm viability and tests of their ability to fertilise in vitro, were carried out, including chromatin condensation, ROS generation, protein tyrosine phosphorylation and heterologous fertilization rate. These showed that epididymal stallion sperm stored for up to 72h in the epididymis at 4°C followed by cryopreservation, maintained both viability and ability to fertilize in vitro.

Although these were laboratory tests of viability, epididymal sperm have been used successfully.


Tuesday, June 04, 2013

When to stop Lyme disease treatment?

Don't expect Borrelia antibodies to disappear rapidly following treatment in horses naturally infected with Lyme disease.

Lyme disease (LD) is caused by systemic infection with the spirochaete Borrelia burgdorferi. The most common signs in affected animals are lameness, often affecting more than one limb, and reluctance to work. Diagnosis of the disease is complicated by the many other possible causes of lameness and the high incidence of sub-clinical infection in areas in which the infection occurs. Many clinically normal animals have antibodies to Borrelia burgdorferi in their blood.

How do you decide on the length of treatment course necessary in cases of Lyme disease in horses?
Changes in the antibody levels are often used to assess when treatment has been successful. In experimental infections, infected animals show marked reduction in antibody levels after antibiotic treatment.

Does the same apply to naturally infected cases? Research in New York State suggests that ELISA serology is less helpful in those cases for determining when treatment is complete.

The study saw Dr Thomas J Divers and colleagues at Cornell Veterinary School  collaborating with Dr Amy L Grice of the Rhinebeck Equine practice in New York State.

Thomas J Divers and colleagues at Cornell Veterinary School and Dr Amy L Grice of the Rhinebeck Equine practice compared Borrelia ELISA antibody concentrations in naturally exposed horses before and after antibiotic treatment for Lyme disease. The study included 68 horses treated with doxycycline or oxytetracycline and 183 horses that received no treatment.

They found that antibiotic treated horses had a decline in ELISA values in comparison to control horses. The scale of the decline in ELISA units following treatment was small compared to that previously reported in experimentally infected and treated ponies.

They conclude: “Persistently high ELISA titres following appropriate treatments for Lyme disease may not, without appropriate clinical signs, be a reason for more prolonged treatment.”