Clover Slobber in Horses
What is Slobbers and What Causes It?
You bring your horse in from the pasture and are alarmed to see saliva pouring out of her mouth. Standing in the cross ties while you groom her, she drools a puddle on the floor. What in the world is wrong? Does this warrant a vet call? Is this a dangerous situation, or just a messy one? Why is one horse slobbering and another is not? And why after years of grazing in a particular pasture this year your horse is slobbering?
White Clover is Common in Many Pastures
Slobbering is Caused by a Fungus Found on Clover
What your horse is suffering from is "clover slobbers." Red clover seems to the most likely species to cause this condition, but all clovers and legumes can host the fungus that causes slobbers. It is not actually the plant itself causing this problem, but a fungus that grows on the plant, or hay made from red clover. The fungus Rhizoctonia leguminicola produces a mycotoxin called slaframine.
The fungus flourishes in cool, wet, and humid conditions. It appears in late spring and early summer and even in fall months as tiny black specks on the clover plants. It is so small that it is difficult to see with the naked eye. Some horses apparently really love clover, while others can take it or leave it, which explains why some horses are affected and others are not. Some horses may be more susceptible than others to the mycotoxins.
That being said, mechanical or chemical reactions to plants can also cause salivation. Irritation from the hairy stems of clover can cause this gross reaction, and plants other than clover including burdock and foxtail can also cause slobbers. One common plant that can cause a chemical irritation is buttercups. The best defense from these weeds is to keep your pastures mowed regularly.
Hay made from the clover can also cause salivation if it contains the fungus. The most immediate danger from clover slobbers is dehydration since the horse is losing fluids from the salivation.
The first thing to do to "cure" slobbers is take the horse off the pasture. The slobbering will cease within 24 hours. Be sure the horse drinks plenty of water. If you notice any symptoms other than the slobbering, or the slobbering does not subside within two days call your vet. He may prescribe an antihistamine. While clover slobbers is not life threatening severe problems can arise if the horse is exposed to the infected clover for a long period of time, including colic and founder.
Mowing the pasture and removing the infected plants can alleviate the problem.