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