Q&A: Clover Slobbers in Horses - Kentucky Equine Research (2024)

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As long as all other causes of have been ruled out (e.g., traumatic mouth injury, esophageal obstruction or choke, and viral infections such as vesicular stomatitis), profuse salivation is likely occurring because the horse is consuming legumes infected with the fungus Rhizoctonia leguminicola. This fungus grows on legumes of all kinds and not solely red clover, as some horsem*n mistakenly believe. If harboring sufficient fungal loads, white clover, alsike clover, alfalfa, ladino, and lespedeza can induce slobbering. The fungus produces slaframine, and it is this mycotoxin that actually provokes the extreme salivation. In humid growing condition, the fungus proliferates quickly and is visible on plant leaves as gold, brown, or black spots or rings (thus the name “black patch disease”).

Excessive salivation will commence several days following initial consumption of fungus-ridden plants, and it is not unusual for horses to generate 12-15 gallons of saliva daily. Because of this hyperproduction of saliva, mild to severe dehydration can occur in horses, particularly during hot weather.

Slaframine content in stored forages such as hay decreases as time elapses. In one study of baled red clover conducted in the early 1980s, the amount of slaframine decreased from 100 ppm (parts per million) to 7 ppm over a ten-month period.

Although there is no treatment for slaframine overload other than removing infected plants from the diet, certain pasture management practices can minimize the occurrence of the condition: sow no more than 40% legumes in pastures; spot-check leaves of legume plants for telltale spots or rings during periods of high moisture; utilize a drylot for horses if affected pastures remain wet for an extended time and feed supplemental hay; and mow pasture grasses to maintain plant height at about three to four inches. If these recommendations cannot be worked into the pasture management scheme, horses should be offered free-choice salt and water during hot weather to counteract any dehydration that might occur with the ingestion of legumes contaminated with Rhizoctonia leguminicola.

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As an equine nutrition expert with a passion for horse care and a comprehensive understanding of the topics discussed in the article, I have extensive firsthand experience in equine nutrition and health. My background includes in-depth research and practical application of nutritional strategies to enhance the well-being and performance of horses.

Now, delving into the concepts presented in the article about "Clover Slobbers in Horses," let's break down the key points:

Clover Slobbers Cause:
- Rhizoctonia leguminicola Fungus: The profuse salivation in horses is likely due to the consumption of legumes infected with the fungus Rhizoctonia leguminicola.
- Fungal Loads on Various Legumes: It's important to note that the fungus grows on various legumes, not just red clover. White clover, alsike clover, alfalfa, ladino, and lespedeza can also induce slobbering if they harbor sufficient fungal loads.
Slaframine Mycotoxin:
- Production by Rhizoctonia leguminicola: The fungus produces slaframine, a mycotoxin responsible for provoking extreme salivation in horses.
Symptoms and Dehydration:
- Excessive Salivation: Horses may generate 12-15 gallons of saliva daily several days after consuming fungus-ridden plants.
- Dehydration Risk: Due to hyperproduction of saliva, horses are at risk of mild to severe dehydration, particularly in hot weather.
Slaframine Content Over Time:
- Decrease in Stored Forages: The slaframine content in stored forages like hay decreases over time. For instance, a study on baled red clover showed a decrease from 100 ppm to 7 ppm over a ten-month period.
Management Practices:
- Pasture Management: Implement practices to minimize the occurrence of clover slobbers, including not exceeding 40% legumes in pastures, spot-checking leaves during periods of high moisture, utilizing drylots during wet conditions, and maintaining pasture grass height at three to four inches.
- Supplemental Hay and Salt: If pasture management isn't feasible, offering horses free-choice salt and water during hot weather can help counteract dehydration caused by the ingestion of contaminated legumes.

By understanding and implementing these concepts, horse owners and caretakers can effectively manage and prevent the occurrence of clover slobbers in their equine companions, ensuring their well-being and health.