Dear Dr. Vittoria: My pony, Top Hat and Tails, aka the naughty Toby, has been having slobbers for the past two weeks. I am worried that he is going to dehydrate from losing all his saliva. Someone told me that the clover in his field is the problem, and I was going to have it sprayed. Do you think this will help? - Victoria from Kutztown

Dear Victoria: Your friend is right in some ways, but it is not just the clover that causes the mouth to slobber. It is a reaction to the toxin from a fungus that causes the problem. The clover plant itself is not toxic. The toxin, slaframine, is made by the fungus, Rhizoctonia, which grows on the clover.

This fungus likes to grow on clovers and alfalfa during times of high humidity, as we have been experiencing. It will be nice when we have some sunny days and dry weather to finally kill the fungus. This fungus typically likes the red clover more than the white, but in the rainy season that we have been having, I think it is an equal-opportunity fungus. I have had many clients with horses affected by this.

The typical symptoms you see are from the toxin exposure. The salivary glands are stimulated and produce so much saliva that it just runs out of their mouths. When you feel the inside of the mouth, it is very swollen and hot. It is like eating a superhot pepper. It tingles and burns, and your salivary glands try to put the fire out that is going on in your mouth. Some horses have their eyes water and refuse to eat, since their mouth hurts.

The best way to treat it is to remove the horses from the infected pasture and mow it down until you don't see any brown spots on the clover. You may want to kill off the clover in your pastures and reseed with grass seed. But you need to allow time for the baby grass to grow before putting your horses back on it. Often it takes a year to really establish new grass growth.

I had a case of the slobbers hit in the dead of winter. I had the owners show me their hay, and sure enough, they must have baled some infected red clover. Unfortunately, they had to throw out all of their hay.

It seems that some horses are more affected than others. So you will have some horses in your field that have terrible problems with it and others that are hardly affected.

Most horses don't need to be treated. Others should have pain medicine and supplemental electrolytes to help replace what is lost.


Dear Readers: After meeting Russ from Mount Aetna, I would like to give a shout out to all the faithful readers who don't even have horses. I am glad you keep reading and enjoying my column and this section of the paper. We appreciate your continued support.

Christina Vittoria, D.V.M., practices equine, small ruminant, and companion animal medicine at Willow Creek Veterinary Center. Comments offered here are for educational purposes only. Readers should consult their veterinarian before taking action. Have a question for Dr. Vittoria? Send it to Please put ASK THE VET in the subject line.