Concerning Collapse

My horse collapsed at a show, but had normal vitals upon standing. Now she’s lethargic. What could be wrong?

No account yet? Register


Q. About two weeks ago my 14-year-old American Warmblood mare that I used for jumpers and preliminary-level eventing randomly collapsed while warming up to jump. She did not trip; it was just more of a drop down and lie there. She lay completely down on her left side, looked to get up, rested her head back down, then finally got up. The episode seemed to last a lifetime, but it was probably only 15-30 seconds. When she got up I walked her around for a bit, then thought to check her gums and heart. Her mucous membranes looked good, and her heart rate was normal with a rate of 36 beats per minute.

Since that episode she has seemed very lethargic and more marish. While working she tires easily and holds her head low. I stop occasionally during workouts to listen to her heart, and it still all seems normal. She does not have any nasal discharge, her appetite and temperature are normal, and so is her respiration and heart rate. I should mention that she is a gray mare, but I cannot find a single melanoma on her body. My vet and I have been trying to figure out what is wrong with my mare, so I thought I would search for some more outside help/input.

Annie, via e-mail

A. Collapse during exercise is certainly a frightening experience for both you and your Warmblood mare. The biggest question is whether the event will reoccur in the future. If a second episode occurs and the cause cannot be identified and controlled, then it would be considered unsafe to ride the mare. Watch the mare’s limbs and face for any unusual scratches or swelling to indicate she might have collapsed and then struggled to rise while being turned out or stabled

Create a free account with to view this content. is home to thousands of free articles about horse health care. In order to access some of our exclusive free content, you must be signed into

Start your free account today!

Already have an account?
and continue reading.


Written by:

Allison Stewart BVSc(Hons), MS, Dipl. ACVIM-LAIM, ACVECC, is a professor of equine internal medicine at Auburn University’s College of Veterinary Medicine in Alabama. Her research interests include equine critical care, neonate intensive care, neurology, equine fungal infections, sepsis, deafness and vestibular disease, and ultrasound.

Related Articles

Stay on top of the most recent Horse Health news with

FREE weekly newsletters from

Sponsored Content

Weekly Poll

sponsored by:

Has your veterinarian used SAA testing for your horse(s)?
67 votes · 67 answers

Readers’ Most Popular

Sign In

Don’t have an account? Register for a FREE account here.

Need to update your account?

You need to be logged in to fill out this form

Create a free account with!