Tuesday, October 25, 2022

Atypical myopathy and acorn poisoning warning

 Horse owners are reminded of the seasonal risks of grazing around oak and sycamore trees. Ingestion of sycamore seeds or acorns can cause rapidly fatal illness in horses.  

“The extreme weather over the summer may have contributed to the production of greater quantities of sycamore masts and acorns than normal,” warned British Equine Veterinary Association president David Rendle.  

“High winds over the next few weeks will likely serve to increase the risk further. Ideally horses should be kept away from grazing around oaks and sycamores but if no other pasture is available supplementary feed should be provided. If horses that have access to sycamore seeds or acorns show signs of illness, veterinary attention should be sought immediately.” 


Seeds (“masts” or “helicopters”) from the common sycamore tree (Acer pseudoplatanus) contain a toxin called Hypoglycin A, which can still be present in high concentrations in seedlings. When horses eat these, either by accident or because they are lacking other forage options, some individuals will develop severe and often fatal muscle damage, called atypical myopathy. 


Horses with atypical myopathy show variable signs of muscle soreness, stiffness, weakness, difficulty breathing, dullness, lethargy, muscle trembling, colic-symptoms, and characteristically, brown or dark red urine. Suspected cases need immediate veterinary attention. Around three quarters of affected horses will die, often despite extensive veterinary treatment but those surviving the initial period will usually go on to make a full recovery.


Acorn “toxicity” is less common and less well understood than hypoglycin toxicity. The apparent increase in cases seen recently may be an unfortunate combination of the extreme dry summer weather and normal variation in acorn production.  Just like all fruit and nut trees, oak trees can produce variable amounts of acorns from year to year, with ‘mast years’ of unusually high production. 


When a group of horses are exposed to acorns from the same oak tree, only one or two horses will fall ill. This may be because individual horses are particularly susceptible, or that some trees, or even certain acorns, are particularly toxic. Protection from acorn toxicity in other species, such as pigs, comes from the production of tannin-binding salivary proteins. These proteins are not normally produced by horses, but it is possible that some individuals have them and are protected in this way. 


The toxic effects of acorn ingestion can be severe and prompt veterinary attention is essential. Clinical signs include moderate to severe colic or colitis, lethargy, dehydration, and dark urine which can be a result of kidney failure. Signs may develop extremely rapidly, and death can occur within a further 12-24 hours. 


Horse owners are advised to take practical steps to prevent the diseases by limiting access to sycamore seeds and acorns:


  • Identify trees both around grazed fields as well as those in close proximity. 
  • Collect seeds or exclude horses from affected areas using electric fencing or stabling. 
  • Feed supplementary hay to try and prevent horses from excessive foraging for short blades of grass and inadvertent ingestion of seeds. But ensure that hay does not become contaminated by seeds.
  • Don’t fell trees when laden with seeds as this can cause a sudden and massive contamination of the pasture. 
  • Monitor horses carefully even after they have been moved from affected pasture as disease can occur up to four days after exposure.


For further information download the Royal Veterinary College’s fact sheet on  Atypical myopathy: https://www.rvc.ac.uk/Media/Default/Comparative%20Neuromuscular%20Diseases%20Laboratory/Atypical%20Myopathy%20fact%20file%20updated%202022.pdf


And see the British Horse Society’s fact sheet on Acorn Poisoning: 




Monday, October 24, 2022

Could stem cells be used to treat equine asthma?

(c) Callipso88 Dreamstime.com

Equine asthma is a common respiratory disease of horses, brought on by repeated exposure to dust and moulds. Although the signs may be improved by medical treatment, this is unlikely to achieve a permanent cure.


Doctor Dorothee Bienzle of the Ontario Veterinary College, University of Guelph, has been investigating stem cells as a potential treatment option, working with a group of researchers at the University of Slovenia who have expertise in growing stem cells. The research is published in Stem Cell Research and Therapy.


She says, “This is not for the casual investigator because it takes some experience to have the right culture conditions to make sure those cells are clean.  They are not cultured for very long, and when the final preparation is administered to an animal, it must be free of cell culture components that could make inflammation worse.”


The study used stem cells derived from subcutaneous fat tissue (“adipose-derived mesenchymal stem cells”: AD-MSC), which were placed directly in the lower airway.


Twenty horses with severe equine asthma (SEA) were divided into two groups: ten horses receiving a single application of autologous AD-MSC; and ten given oral dexamethasone daily for three weeks.


Horses were assessed before treatment and three weeks later. The research team also monitored the horses for recurrence of SEA over the following year.


They found that AD-MSC administration improved the clinical score and decreased the expression of inflammatory markers (such a IL-4, IL-1b) in the broncho-alveolar lavage fluid. 

It took longer for signs of SEA to return in horses treated with stem cells. The researchers noted exacerbations of SEA in the dexamethasone-treated  group shortly after discontinuation of treatment, while most horses in the AD-MSC treated group remained stable for at least 300 days after treatment.


They conclude: “In this study, the intrabronchial application of autologous AD-MSC had a modest short-term therapeutic effect and a possible positive long-term effect on SEA.”


Speaking about the work in an Equine Guelph webcast* Dr Bienzle added: “Stem cell therapy is a proof of concept at this point. It is not widely available and we don’t want to mislead people ..that this is a commonly available therapy. We’re a long way from that, but horses may get there before humans do.”


For more details, see:


Effect of intrabronchial administration of autologous adipose-derived mesenchymal 

stem cells on severe equine asthma 

Neža Adamič, Sonja Prpar Mihevc, Rok Blagus, Petra Kramarič, Uroš Krapež, Gregor Majdič, Laurent Viel, Andrew M. Hoffman, Dorothee Bienzle and Modest Vengust

Stem Cell Res Ther. 2022; 13: 23. 




Tuesday, October 18, 2022

Cloned Przewalski’s horse learning the language of wild horses


From left to right: Kurt, the world’s first cloned Przewalski horse, and Holly, in a field habitat at the San Diego Zoo Safari Park.  Ken Bohn, San Diego Zoo Wildlife Alliance
Kurt, the world's first cloned Przewalski's horse (L)
and Holly (R) at San Diego Zoo  Safari Park
(c) Ken Bohn, San Diego Zoo Wildlife Alliance
A rare Przewalski’s horse, named Kurt, produced by cloning in 2020 is thriving at his home at the San Diego Zoo Safari Park and learning the language of being a wild horse from Holly, a young female of his own species. 

Kurt was cloned from the DNA of a Przewalski's horse that was frozen 42 years ago. It's hoped that once he reaches maturity in a couple of years, he will be able to breed and return lost genetic diversity to his species.


By the end of the 1960s, the Przewalski horse, considered to be the last truly wild horse, was extinct in the wild. Some individuals survived in zoos, and an intensive breeding program managed to revive the species, allowing horses to be reintroduced to their natural habitat in the 1990s. 


Although there are now over 700 animals roaming the Mongolian steppes, almost all are related to just 12 individuals. This loss of genetic diversity is a cause for concern; maintaining genetic variation is likely to be an important part of ensuring the species’ survival in the future.


Kurt was born to a surrogate mother, a domestic quarter horse, which means he had no experience of other Przewalski’s horses. San Diego Zoo Safari Park wildlife care experts embarked on an effort to ensure the young male gained the behavioral language he will need to interact and thrive among his own species.  


“Przewalski’s horses normally live in groups where a youngster secures their place in the herd from their mother,” said Kristi Burtis, DM, director of wildlife care, San Diego Zoo Safari Park. “Because Kurt was not born into a herd, he didn’t know the behavioral language that is unique to Przewalski’s horses. Our first step to socialize him was introducing him to Holly.” 


Holly arrived at the San Diego Zoo Safari Park in May 2021. Just a few months older than Kurt, Holly was raised in a Przewalski’s horse herd and had the full repertoire of wild horse language to share. Wildlife care specialists at the Safari Park introduced the two, hoping that Holly could serve as a mentor and teacher to Kurt. 


After some behavioral sparring, the two have settled into an affectionate pairing. Kurt and Holly have been in a secluded, private habitat since their arrival at the Safari Park and were recently introduced to the Safari Park’s Central Asia field habitat, where they are now viewable by guests. This move will further prepare them to soon join the larger herd of Przewalski’s horses, and the plan is for Kurt to be the breeder stallion when he reaches maturity at 3 to 4 years of age. 


“Kurt is significant to his species because he offers the hope of bringing back lost genetic diversity to the population,” said Dr Nadine Lamberski, chief conservation and wildlife health officer, San Diego Zoo Wildlife Alliance. “It is imperative to do everything we can to save this genetic diversity before it disappears.” 


By reviving genetic diversity that was stored in San Diego Zoo Wildlife Alliance’s Biodiversity Bank, conservationists hope to expand the strength of the species’ population.


For more details, see:



Monday, October 17, 2022

Do younger parents breed faster racehorses?

 Recent research shows that increasing parental age at conception has a detrimental effect on race speed.

 When a split-second can separate the horses at the end of the race, the slightest advantage can give the winner the edge. Research from the university of Exeter found that the speed of thoroughbred horses declines as the age of their parents when they were conceived increases. 


Dr Patrick Sharman and colleagues at the Centre for Ecology and Conservation, University of Exeter, analysed 906,027 racing performances of 101,257 horses -   the offspring of 41,107 dams and 2887 sires. The study included data from almost 25 years of racing results, from 1996-2019, involving meetings across Great Britain. The work is published in Royal Society Open Science.


Dr Patrick Sharman said “The fact that parental age affects racehorse speed should be of interest to the horseracing industry.  More generally, it adds to an increasing body of evidence which points towards parental ‘state’ at the time of conception having an influence on offspring phenotype. This would have implications well beyond racehorses and the horseracing industry” 


They found a ‘significant effect’ of maternal age on speed, with each additional year of age at conception decreasing the offspring speed by 0.017 yards per second.  


This may not sound very much, but they suggest it could produce a one second difference in a race over a mile between horses born to a five-year old and a 15-year old mother.


Also, they found that the paternal age showed a decrease of 0.011 yards per second for every increasing year in stallion age.


Sharman added: “It is perhaps not surprising that offspring speed declines with increasing maternal age. It is the dams, after all, who care for the foal, first in utero, and then through to around 6 months of age. 


“What I find fascinating, though, is that increasing paternal age also causes a significant decline in racehorse speed. Thoroughbred stallions play no part whatsoever is raising a foal, so what is behind this decline in speed?” 


The authors conclude: “Our analysis identified significant negative within-parent effects of advancing maternal and paternal age on offspring speed. While we had expected to find some evidence of parental age effects, their magnitude is notable, particularly that of the previously undocumented influence of paternal age on offspring speed.” 


They hope that their findings will prompt research into the mechanisms by which these parental age influences are transmitted to the offspring.


For more details, see:


Evidence of maternal and paternal age effects on speed in thoroughbred racehorses

Patrick Sharman, Andrew J. Young, Alastair J. Wilson

Royal Society Open Science Vol 9, no 10 (2022)



Friday, October 14, 2022

Can you help with a senior horse survey?

 If your horse or pony is 15 years or over, the team at the SPILLERS feed company is urging you to spare five minutes to participate in their senior horse survey. The results will help them learn more about the specific needs of older horses and every participant will have the chance to win free feed.

Traditionally, senior horses and ponies were classed as being 15 years or over, but perspectives are changing. Management and care continue to improve, and around 40% of horses and ponies in the UK now sit in this 15+ category. 


“If you own or care for a horse or pony who is 15 years or over, we would be very grateful if you could spare five minutes to participate in our survey,” said SPILLERS Product Manager Sarah Nelson. “The results will help us to help more senior horses nutritionally, in the very best ways we can.” 


If you would like access to the survey results, just add your email address at the end of the survey. If you submit your email address, you’ll also be added to a prize draw for your chance to win a £50 SPILLERS Feed voucher.


The survey is set up with one horse or pony in mind. If you own more than one horse or pony of 15 years or over, they ask you to complete a survey for each horse. Every completion will provide an additional entry into the prize draw.


Click here to complete the survey https://www.smartsurvey.co.uk/s/Seniorsurvey/

Tuesday, October 11, 2022

Free nutrition webinars

For a second year, MARS EQUESTRIAN™ are sponsoring a series of virtual educational webinars covering nutrition
research, nutritional advice, and the latest in laboratory diagnostics and medical imaging. All will be available free of charge. 

Published times, dates and topics are as follows: 


  • 10AM EDT, October 22, 2022 – Keeping the performance horse healthy and active. “The focus of this first webinar is keeping the performance horse healthy and active. The updates on our core research, diagnostic tools and nutritional recommendations will focus on the specific needs of working horses.”
  • 10AM EDT, October 29, 2022 – Keeping the gastrointestinal tract healthy. “The focus of this, the second webinar, is feeding specifically for the gastro-intestinal tract, as well as diagnosing problems and our research behind key nutritional recommendations.”
  • 10AM EDT, November 5, 2022 – Keeping the performance horse mobile and active. “The focus of this, the third webinar, is keeping the performance horse mobile and fit. Techniques for measuring fitness, imaging and diagnosing lameness as well as relevant nutritional recommendations will be discussed.”


Each webinar session must be registered for individually. For those who are unable to attend the live event, recordings will be available afterwards, as are recordings of last year’s webinars, covering obesity, the senior horse and laminitis.


For more information, go to: