Koper Equine

Over-salivation, or excessive drooling, in horses after eating clover is often caused by a natural substance found in certain types of clover called slaframine. Slaframine is a mycotoxin produced by the fungus *Rhizoctonia leguminicola*, which commonly infects red clover and, to a lesser extent, white clover and alsike clover.

Key Points

1. Cause: Slaframine stimulates the salivary glands in horses, leading to excessive salivation. This condition is sometimes referred to as “slobbers.”
2. Symptoms: In addition to excessive drooling, other symptoms can include watery eyes, diarrhea, and frequent urination. However, drooling is the most common and noticeable symptom.
3. Toxicity: While the slobbers caused by slaframine are usually not harmful and tend to resolve on their own once the horse stops eating the contaminated clover, they can be inconvenient and messy. In severe cases, prolonged exposure can lead to dehydration or nutritional imbalances due to the loss of fluids.
4. Prevention: Managing pasture to reduce the presence of infected clover can help prevent slobbers. This includes rotating pastures, avoiding grazing in wet conditions that promote fungal growth, and possibly reseeding with less susceptible forage species.
5. Management: Removing the horse from the contaminated pasture usually results in the cessation of symptoms. Providing fresh water and monitoring the horse for signs of dehydration is important. In most cases, no specific treatment is required, but consulting a veterinarian for persistent or severe cases is recommended.

Some horses react more intensely than others

This can be influenced by several factors:

1. Individual Sensitivity: Just as with humans, individual horses can have varying sensitivities to different compounds. Some horses might be more sensitive to slaframine, the mycotoxin responsible for slobbers and may react to a single bite.
2. Grazing Habits: Horses that graze more extensively or prefer clover to other types of forage are more likely to ingest larger amounts of slaframine, increasing their risk of over-salivation.
3. Immune System Variability: Differences in immune system function can also play a role. Horses with weaker immune systems might be more susceptible to the effects of mycotoxins.

Preventive Measures

• Pasture Management: Rotating pastures and reducing clover density can help minimize exposure.
• Forage Selection: Introducing a variety of forages to reduce or eliminate the reliance on clover.
• Monitor Consumption and Grazing Habits: Observing horses’ grazing habits and limiting access to clover-rich pastures during times when fungal growth is likely.

For more detailed information, you can refer to these sources

• The Horse: Slobbers: Causes and Treatments
• Kentucky Equine Research: Clover Poisoning
• University of Minnesota Extension: Red Clover and Slobbers