White clover flowers in spring, shallow depth of field
If your horse is drooling excessively, it could be due to the fungus Rhizoctonia Leguminicola, or “black patch.” This fungus grows on clover and other legumes and produces the chemical slaframine. Slaframine is what causes the excessive drool.
Black patch grows best in the spring and fall, and with the high rain fall and humidity of the past spring, the growing condition is perfect. If your pasture is infected with the fungus, clover will have brown to black rings on the underside of the leaves and stems. Be aware: the fungus is not limited to infecting red and white clover. All legumes, like alfalfa, can grow slaframine so check your pasture and hay carefully.
Symptoms can begin within one to three hours after ingestion. Slaframine is generally harmless and symptoms should subside 24-72 hours after the horse no longer has access to the infected legume.
Symptoms of slaframine ingestion include:
- Extreme salivation
- Diarrhea
- Mild bloat
Infected legumes are not the only cause of excessive drooling. It’s important to rule out:
- Mouth injuries
- Infections like vesicular stomatitis
- Dental problems like sharp point and ulcers
- Choke
If you suspect one of these medical conditions, contact your veterinarian.