An anti-snake venom drug will be trialled on a small group of horses later this year in an attempt to find a cure for equine grass sickness (EGS), revealed Professor Bruce McGorum, Professor in Equine Medicine at the Royal (Dick) School of Veterinary Studies in Edinburgh, during a presentation at the recent National Equine Forum in London.
It is hoped that this drug will significantly improve the number of horses that survive equine grass sickness, which currently stands at just 20%.
A weather app is also being designed by Hayley Coulson at the University of Edinburgh which warns of high risk weather that will potentially trigger episodes of EGS. Owners can then bring their horses off the pastures to help reduce the risk of disease.
In December 2024, Your Horse reported that researchers had identified the cause of EGS to be a neurotoxin produced by pasture microbes.
The researchers, who hailed from the Royal (Dick) Vet Equine Hospital, University of Edinburgh, Newcastle University, Istituto Zooprofilattico Sperimentale delle Venezie, and the University of Padova, believe the cause of EGS is neurotoxic phospholipase A2, a toxin which is present in the venom of many poisonous snakes.
Treat and promote nerve regeneration
It is hoped that some of the drugs used to treat and promote nerve regeneration in people who have been paralysed by snake venoms may be able to help horses recover from EGS.
“If we compare the clinical signs and the consequences of grass sickness versus human envenomation you can see a lot of similarities [but] there are some subtle differences,” explained Professor McGorum.
“The grass sickness horse has a predominant dysfunction of the intestine, whereas the people tend to die with respiratory paralysis.
“They have more of a consequence on the muscle, and this probably reflects the different route of exposure in the horse versus the snake bite victim.
“In the snake bite victim, the venom will be injected directly into the muscle or directly into the blood, where it will target the muscle more clearly, whereas we are proposing that the horses are getting toxin from the intestinal tract and have a more profound consequence in the intestinal tract.”
Reducing number of snake bite deaths
Bruce and his team of researchers are collaborating with the World Health Organisation who have a strategy to reduce snake bite death and disability by half by 2030. It is estimated that each year there are two million envenomations and between 80,000-130,000 deaths.
“They’re recognising the current anti venom treatment has limited efficacy and limited availability, perhaps, and they’re trying to develop alternative drug to treat people with snake envenomations, particularly in rural communities,” continued Professor McGorum.
“This is one drug that they’re using in a trial this year in Asia, and this has been selected because it has efficacy in a mouse envenomation model.
“They inject venom into mice, and four hours later, they give this drug, and it does improve survival. It improves muscle function and improves nerve regeneration.
Treatment trial to start this spring
“We plan to use this in a small group of horses in a treatment trial later this spring to determine whether this can improve survival of horses, or whether, perhaps unfortunately, the nerve degeneration is too far advanced to make a significant improvement.”
Professor McGorum also revealed that work is ongoing at the University of Edinburgh and the University of Surrey to identify the source of the toxin that causes EGS. A bio bank which contains archived samples from horses and pastures affected by the disease has been made available to those researching the subject.
EGS was first recognised in eastern Scotland in 1907. It is highly complex and involves damage to the horse’s autonomic nervous system, which functions unconsciously and regulates internal body functions such as gut peristalsis.
The latter moves the food along the gut during the digestive process. It is this gut function that is damaged in equine grass sickness, with a whole or partial gut paralysis resulting.
Elsewhere at the National Equine Forum
Also at the National Equine Forum, Defra minister Baroness Hayman of Ullock announced that the development of a much-needed digital equine identification and traceability system has been paused by the government due to costs.
Former Retraining of Racehorses chief executive Di Arbuthnot received the Sir Colin Spedding Award in recognition of her dedication to racehorse welfare.
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