Why is My Horse Drooling Excessively? Causes and Care

Excessive drooling, or hypersalivation, can be surprising and messy for horse owners. Some horses slobber more than others, and while it may seem harmless, it can be caused by various factors that owners should understand to respond appropriately.

Common Causes of Excessive Drooling in Horses

1. Fungal Toxin: Slaframine from Clover

One of the most frequent reasons a horse drools excessively is due to slaframine toxicosis. This condition occurs when horses ingest a specific fungus called Rhizoctonia leguminicola, which grows on white and red clover. The toxin produced irritates the horse’s mouth and stimulates saliva glands, causing noticeable slobbering. This is especially common when horses graze on pastures rich in clover during the summer months.

Typically, the horse will start drooling excessively while eating or even while standing still, sometimes resulting in a wet patch or puddle under their head. Fortunately, this condition usually resolves when the horse is removed from the affected pasture or clover-containing hay, and no long-term harm typically occurs.

2. Mouth Lesions or Dental Issues

Lesions or injuries to a horse’s tongue or inside the mouth can lead to hypersalivation. Common dental problems such as sharp teeth, abscesses, or foreign bodies lodged in the mouth can also trigger excessive drooling. Routine dental care by a qualified equine dentist or vet is essential for preventing and managing these causes.

3. Esophageal Obstruction (Choke)

An obstruction in the esophagus, sometimes called "choke," can cause saliva to build up as the horse has difficulty swallowing. This leads to drooling and sometimes nasal discharge as saliva may escape through the nostrils. It’s a serious condition needing prompt veterinary attention to gently relieve the obstruction and ensure no damage is done to the food passage.

4. Toxicity or Irritating Chemicals and Plants

Some chemicals like freshly painted fences or ingesting toxic plants such as buttercups or marigolds can irritate the horse’s mouth and cause increased drooling. Physical irritation from plants like burdock or foxtails can also produce excessive saliva. Checking your horse’s environment and diet carefully is vital to avoid exposure to harmful substances.

5. Infectious or Serious Diseases

Rare but very serious conditions such as vesicular stomatitis or even rabies can cause hypersalivation. These conditions usually present with additional signs such as mouth lesions, lameness, neurological symptoms, and behavioural changes. If these signs accompany drooling, veterinary evaluation must be immediate.

6. Normal Behavioural Drooling

Many horses naturally produce large amounts of saliva daily—up to 10 gallons—and it is normal for horses to slobber during certain activities like working their bit when being ridden. This type of drooling is typically white and frothy and not a cause for concern.

How to Identify Contaminated Clover in Pasture

To recognise if pasture might be causing slobbering, inspect red or white clover plants carefully. Fungal-contaminated clover leaves often have a greyish tint instead of the usual bright green and may turn black as the infection progresses. Horses usually avoid eating large amounts, but continuous grazing on such pasture may cause excessive drooling.

When to Seek Veterinary Help

While some causes of drooling are mild or normal, owners should contact a vet immediately if the horse:

• Develops a sudden increase in drooling combined with loss of appetite;
• Shows difficulty swallowing or distress;
• Appears lethargic or feverish while drooling;
• Produces thick or discoloured saliva;
• Exhibits other signs like mouth sores, lameness, or neurological symptoms.

A vet will conduct a thorough examination, check the horse’s mouth, throat, and environment, and may run tests to diagnose the exact cause. Early intervention can prevent complications and treatment tailored to the specific problem is essential for recovery.

Conclusion

Excessive drooling in horses can stem from a variety of causes, ranging from harmless pasture fungi to serious diseases. Understanding the common causes such as contaminated clover pastures and dental issues is key for responsible horse ownership. Regular health checks, careful pasture management, and prompt veterinary care when abnormal symptoms appear will help keep your horse happy and healthy.