A horse that collapses while under saddle is both a hazard to himself and others. What does this mean for his potential as a mount, though? For many horses, suffering an episode of collapse (when a horse falls suddenly with or without recumbency--the inability to stand--or loss of consciousness) is a once-in-a-lifetime occurrence, according to a Scottish researcher.
"Riding is a dangerous sport whether or not a horse has a history of collapse," said John A. Keen, BVetMed, PhD, Cert EM (Int Med), Dipl. ECEIM, MRCVS, RCVS and European Specialist in Equine Internal Medicine from the University of Edinburgh, in Scotland. "Collapse is, thankfully, rare. A horse is probably more likely to trip, fall, or get a fright than collapse."
Keen and his colleagues conducted a retrospective study of 25 equine collapse cases in an attempt to characterize causes and outcomes. All horses in the study were thought to be healthy when the incident occurred.
Diagnosing the cause of collapse is often difficult and, therefore, it can be hard to predict if or when the horse will collapse again, Keen said. However, many horses that collapse once (whether or not a cause for the collapse was determined) never collapse again.
Although a collapse may seem to warrant the end of a horse's riding days, the prognosis for most horses that have collapsed is generally good. In Keen's study, veterinarians made a definitive diagnosis in 11 cases. These diagnoses included cardiac arrhythmia (irregular heartbeat), right-sided heart failure, hypoglycemia (low blood sugar), generalized seizures, and sleep disorders (accompanied by loss of muscle tone). Veterinarians reached presumptive diagnosis in eight cases, and these included syncope (fainting caused by a drop in arterial blood pressure), exercise-induced pulmonary hemorrhage, and generalized seizures. No diagnosis was made in six cases despite comprehensive investigations. Only one of the 25 horses was observed to collapse after discharge.
A definitive diagnosis often can help veterinarians prevent another collapse from happening, if it's a condition they can prevent with management methods or treatments.
Keen suggested that following a horse's first collapse owners wait six months before riding the horse again. If the horse does not display any abnormal clinical signs and remains healthy as confirmed by both the veterinarian and horse owner/caretaker, he added, it might be possible for the horse to resume his career under saddle.
"This seems sensible advice for (the owner of) any horse that has collapsed only once, with no specific diagnosis, rather than potentially subjecting a 'normal' horse to pasture rest for the rest of its life," Keen said. However, there are no guarantees that the horse will not collapse again, he reminded.
If the owner decides to ride the horse, Keen suggests starting slow and spending time doing low-risk training such as hacking or working in an arena. Always have someone else present when schooling these horses, he cautioned.
"Ultimately, owners must make their own decisions about these horses in communication with their own veterinarians," he said. "If the horse is collapsing, or there is suspicion that this is the case--such as unusually disturbed bedding, or unexplained bruises or cuts around the head¬--owners should take increased care and seek veterinary advice promptly."
If a horse collapses, Keen recommends owners record the following information about the incident to accurately inform the veterinarian about the episode:
- What preceded the episode?
- How did it happen?
- How long was the horse down?
- Did he move when down?
- How did he get up?
Keen added that video footage can help veterinarians' evaluations of a collapse.
The study, "Retrospective evaluation of episodic collapse in the horse in a referred population: 25 cases (1995-2009)," was published in the November-December issue of the Journal of Veterinary Internal Medicine. The abstract is available on PubMed .
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Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.