The Mysterious Fever of Unknown Origin
Better understand this common—and frustrating—condition seen in horses

He’s just a little off. It’s hard to say exactly what’s going on. But he’s your horse, and you know him so well you pick up on the slightest little nuances when something is wrong.
So, you check him all over: no signs of injury, no strange bug bites, no drainage coming out of the nose, no diarrhea, no cough. Then you take his temperature.
Sure enough, fever. Something is wrong. But what?
Welcome to the world of fever of unknown origin. For both owners and their treating veterinarians, this condition can be fraught with frustration, confusion, guesswork, and a Sherlock-Holmes-like investigative process with some modern technological flair.
Fortunately, through strong collaborations with laboratories and referral clinics, horses with fevers of unknown origin can often get the diagnoses and targeted treatment they need.
“At first, it’s unknown origin—but we hope to give it an origin, and give that horse a diagnosis,” says Toby Pinn-Woodcock, DVM, Dipl. ACVIM, assistant clinical professor in the Department of Population Medicine and Diagnostic Sciences at Cornell University College of Veterinary Medicine, in Ithaca, New York.
Understanding Fever in Horses
More than ever, horse owners are tracking their horses’ body temperatures, our sources say.
Technology has certainly played a role in that—thanks to rubbery digital thermometers that beep with a digital reading less than 30 seconds after being inserted in the horse’s rectum. Veterinarians can also now implant microchips with temperature sensors into a horse’s neck, which send real-time data to mobile phones and alert you if the temperature is abnormal
This story requires a subscription to The Horse magazine.
Current magazine subscribers can click here to and continue reading.
Subscribe now and gain unlimited access to premium content.
Subscribe NowWe at The Horse work to provide you with the latest and most reliable news and information on equine health, care, management, and welfare through our magazine and TheHorse.com. Our explanatory journalism provides an understandable resource on important and sometimes complex health issues. Your subscription will help The Horse continue to offer this vital resource to horse owners of all breeds, disciplines, and experience levels.

Related Articles
Stay on top of the most recent Horse Health news with