Why Does My Horse Drool so Much?

Q. My 18-year-old Arabian gelding likes to drool. My veterinarian has examined my horse and his teeth and says my horse is in excellent health. The drooling is not continuous--it just happens every once in a while, and he'll spit a slobber out. It's pretty gross. My questions on horse slobber are:

  1. Could this be an allergy?
  2. Is it more behavioral because I give him treats? My vet calls me a "Pez Dispenser"; maybe my horse sees me and starts to salivate?
  3. He gets plenty of water, but does he need electrolytes even in winter?

Nancy, via e-mail

A. Thank you for your question. It sounds like an interesting case, and it is great that you are already working with your veterinarian who has completed a thorough oral examination.

Excessive drooling, or hypersalivation, can have several potential causes. One of the most common causes is slaframine toxicosis from ingesting mold on red clover. Most horses stop the drooling when they are taken off the inciting pasture, although hay might potentially result in exposure as well. That seems unlikely based on the history you have provided.

Other causes include lesions of the oral cavity and tongue, such as dental disease, foreign bodies, grass awns, or abscesses. One horse that I examined about a year ago had a thin wire through her tongue, which was not visible until we took X rays.

Esophageal obstruction and gastric ulceration are potential causes of excess salivation as well. I would not expect an allergy or treats to cause what you have described, but I would certainly defer to your veterinarian who knows your horse and the extent of the situation. If the problem persists or worsens, I would recommend some additional diagnostic tests (such as X rays, ultrasound, endoscopy, and/or CT scan) to rule out a lesion in the mouth or tongue.

About the Author

Amanda Martabano House, DVM, Dipl. ACVIM

Amanda Martabano House, DVM, Dipl. ACVIM, is an assistant professor in the department of large animal clinical sciences at the University of Florida's College of Veterinary Medicine.

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