It’s springtime and the horses have been grazing in the lush pastures, but they seem to be salivating excessively. Could this be a case of clover slobbers, and what does this actually mean for my horse?
Clover slobbers is a condition where horses start salivating profusely after an exposure to fungus affected plants. The fungus involved in this phenomena is called Rhizoctonia Leguminicola, and is easily recognizable by its black patch formation which can be found on the leaves and stems of the infected greenery. This particular strain of fungus is commonly associated with clover and alfalfa filled pasture and hay as it provides an ideal host. It typically thrives in spring and fall as the cool wet conditions create a perfect breeding ground for these plants and fungus alike.
But what about this fungus causes your horse to salivate? The fungus produces the mycotoxin Slaframine, which irritates the mouth and produces the slobbers. These mycotoxins are created when the fungus parasitize the host plants during growth. The true purpose of mycotoxins is a bit of a mystery as they do not directly contribute to the growth or development of the fungus, but it has been speculated that it may be a tactical effort to create a better environment for further fungal proliferation. If untreated, this fungus can continue to thrive and spread through adjoining pastures and hay fields. In addition to surviving in the fields this particular fungus can survive for up to 10 months in hay stores, however its potency will decrease over time.
Typically slobbers are harmless, and will resolve themselves once the infected source is removed from your horse’s diet. However in some cases, although rare, more sensitive horses may present other symptoms such lacrimation, colic and diarrhea. Symptoms often develop 1-3 hours after consumption of infected pasture forage or hay and subside within two to three days. It is also important to keep in mind that excessive drooling can be a sign and symptom of other health concerns such as Vesicular Stomatitis, chemical irritants, and irritation caused by consuming other vegetation. Be sure to check your horse’s gums, tongue, lips, and palate for signs of irritation or lesions to rule out other causes. If symptoms persist, or your horse’s condition deteriorates it is best to contact your veterinarian.