Question

I moved my Arabian mare to a new boarding barn in the winter. I chose this facility in part because of the well-maintained pastures and abundant grazing. This spring and early summer my mare began to slobber excessively. When she opened her mouth to accept the bit, saliva gushed from her mouth. The barn owner, who has housed horses on the property for nearly three decades, said it was due to a naturally occurring fungus on some pasture grasses and as long as my mare has water available to her (which she does), she would be fine. Does this sound on the up-and-up to you?

Answer

A pasture fungus called “black patch” affects many legumes, including certain types of clover. The fungus produces a compound called “slaframine,” which is known to cause excessive salivation in horses and other animals. The fungus seems to be particularly prolific during stretches of wet, cool weather.

In some parts of the U.S., slaframine exposure is common, especially when environmental conditions are ripe for fungal spread. As the barn owner alluded to, there is typically little to worry about in terms of your mare’s health, especially if she appears and acts normal in every other way.

Dealing with the excessive salivation can be tedious at times, but once most horse owners have an understanding of the cause, they seem to manage well. Access to clean, fresh water will help prevent dehydration that might creep into the picture if the mare sweats significantly during exercise or turnout.

Even though slobbers caused by fungal disease of pasture plants seems the likeliest cause, especially if your mare’s stablemates are similarly affected, a once-over by a veterinarian is always sound horsemanship when any unusual situation arises with a horse.