Why Is My Horse Drooling So Much?

By Dr Duncan Houston

Finding your horse with saliva dripping from the mouth can look dramatic. Sometimes it is a fairly simple forage-related problem called slobbers. Other times, drooling can be a warning sign of choke, mouth injury, toxic exposure, neurological disease, or a reportable infectious disease.

Slobbers is most commonly linked to a fungal toxin called slaframine, usually found on affected clover or legume forage. It stimulates the salivary glands and can make a horse drool heavily, even while otherwise looking bright and normal. In typical slaframine cases, the mouth itself has no ulcers or wounds, and signs improve once the contaminated forage is removed. (MSD Veterinary Manual)

The key is not to panic at every wet chin. The key is knowing when drooling looks like simple slobbers and when it looks like something that needs urgent veterinary care.

Quick Answer

Slobbers in horses is excessive salivation most often caused by eating clover or other legume forage contaminated with the fungus Rhizoctonia leguminicola, which produces the toxin slaframine. Most horses recover after the affected pasture or hay is removed, often within 24 to 48 hours, but drooling is not always harmless. Call your vet urgently if your horse has feed or saliva coming from the nostrils, trouble swallowing, mouth ulcers, weakness, fever, colic signs, breathing difficulty, or is not eating or drinking normally. (MSD Veterinary Manual)

What Are Slobbers in Horses?

“Slobbers” is the common name for excessive salivation caused by slaframine toxicosis.

Slaframine is a toxin produced by a fungus that can infect forage, especially clovers. When a horse eats enough affected forage, the toxin stimulates the salivary glands. The result can be an impressive amount of drool, sometimes enough to wet the chest, forelegs, stall floor, or feed tub. (MSD Veterinary Manual)

A classic slobbers case usually looks like this:

• Heavy drooling

• Horse otherwise bright

• Normal breathing

• No obvious mouth ulcers

• No feed coming from the nostrils

• Recent access to clover-rich pasture or affected hay

• Other horses on the same pasture or hay may also drool

That last point is useful. If several horses eating the same hay or grazing the same paddock start drooling at the same time, a feed or pasture cause moves higher on the list.

What Causes Slobbers?

Slobbers is usually caused by horses eating forage contaminated with Rhizoctonia leguminicola, a fungus associated with black patch disease in legumes. The fungus produces slaframine, which causes excessive salivation. (MSD Veterinary Manual)

Common forage sources include:

• Red clover

• White clover

• Alsike clover

• Alfalfa

• Clover-rich hay

• Silage or forage stored in damp conditions

Red and white clover are common culprits, and alfalfa can be involved less often. Damp, humid conditions can make fungal growth more likely, especially when forage is mature, stressed, or poorly dried before baling. (Penn State Extension)

This is why slobbers may appear suddenly after a change in hay, a move to a new paddock, wet weather, or grazing in a clover-heavy field.

Is Slobbers Dangerous?

Most uncomplicated slobbers cases are more messy than dangerous.

The horse may look ridiculous, like they have lost an argument with a leaking tap, but if they are bright, eating, swallowing normally, and breathing comfortably, slaframine exposure is usually less concerning than it looks.

That said, excessive drooling still deserves attention because:

• Drooling can contribute to dehydration if severe or prolonged

• Slobbers can be confused with more serious disease

• Some toxic or neurological conditions also cause salivation

• Choke can cause drooling and feed material from the nose

• Mouth ulcers, wounds, dental disease, or vesicular disease can cause drooling

MSD Veterinary Manual notes that profuse ptyalism may be the only sign of slaframine toxicosis and that affected animals usually have no oral ulcers or mouth lesions. That is a major clue. If you see ulcers, swelling, blood, feed from the nostrils, weakness, or marked pain, do not assume it is simple slobbers. (MSD Veterinary Manual)

What Does Slobbers Look Like?

The main sign is excessive saliva.

You may see:

• Clear saliva dripping from the mouth

• Wet patches on the chest or front legs

• Foam around the lips

• Saliva soaking feed or bedding

• Normal appetite, or slightly reduced appetite

• Mild tearing from the eyes

• Mild diarrhoea

• Frequent urination

• Mild bloating in some cases

Merck notes that slaframine toxicosis can cause salivation within hours of eating contaminated hay, and other signs may include mild lacrimation, diarrhoea, mild bloat, and frequent urination. Death is not typical, and appetite often returns after the contaminated feed is removed. (MSD Veterinary Manual)

The key practical distinction is this: a horse with slobbers can usually swallow. A horse with choke often cannot swallow properly.

How Worried Should You Be?

The amount of drool alone does not tell you how serious the problem is. The horse’s overall condition matters more.

The most important checkpoint is whether your horse can swallow normally. If saliva or feed is coming from the nostrils, treat it as possible choke, not simple slobbers. Merck lists nasal discharge of feed material or saliva, dysphagia, coughing, ptyalism, anxiety, and neck stretching as signs of esophageal obstruction in horses. (Merck Veterinary Manual)

Slobbers vs Choke

Choke in horses is an esophageal obstruction. It is not the same as a person choking on their airway, but it is still an equine emergency.

A horse with choke may show:

• Saliva or feed material coming from the nostrils

• Coughing

• Repeated swallowing

• Stretching or arching the neck

• Anxiety or distress

• Not eating normally

• Gagging or retching motions

• Drooling

AAEP notes that feed material from the nostrils is one of the most recognised signs of choke, and that choke episodes can have serious consequences, so veterinary evaluation should happen promptly. (AAEP)

If you suspect choke, remove feed and water while you call your vet. Do not try to hose anything down the throat. Do not force the horse to drink. Do not wait overnight to see if it sorts itself out.

That is how a drooling horse becomes a pneumonia horse, and nobody ordered that upgrade.

What Else Can Cause Excessive Drooling in Horses?

Slobbers is common, but it is not the only cause of drooling.

Other causes include:

• Choke

• Dental disease

• Mouth ulcers

• Tongue injury

• Foreign body in the mouth

• Sharp feed material

• Bit or bridle trauma

• Vesicular stomatitis or other vesicular diseases

• Toxic plants or chemical exposure

• Irritating medications or oral pastes

• Botulism

• Neurological disease affecting swallowing

• Severe colic or distress

• Rabies in regions where it is a risk

MSD lists vesicular stomatitis, foot-and-mouth disease, bluetongue, and vesicular exanthema among important differential diagnoses for large animals with salivation and oral-type signs. (MSD Veterinary Manual)

Botulism is another serious rule-out when drooling occurs with weakness or swallowing difficulty. MSD describes botulism signs in horses as progressive paralysis, difficulty chewing and swallowing, weakness, muscle tremors, stilted gait, and eventually breathing difficulty in severe cases. (MSD Veterinary Manual)

So, slobbers is usually simple. Drooling plus weakness is not.

How Do You Tell Slobbers From Something More Serious?

Look at the whole horse, not just the saliva.

Slobbers is more likely when:

• The horse is bright and alert

• Appetite is normal or only mildly reduced

• Swallowing is normal

• There is no feed coming from the nostrils

• There are no visible mouth ulcers

• Several horses on the same forage are affected

• There has been recent access to clover-rich pasture or hay

• Signs improve after changing forage

Something more serious is more likely when:

• The horse cannot swallow

• Feed or saliva comes from the nostrils

• The horse coughs repeatedly

• The horse is weak, dull, feverish, or uncoordinated

• There are mouth ulcers, blisters, bleeding, or swelling

• Only one horse is affected and there is no obvious forage link

• Drooling continues despite removing suspect feed

• The horse has colic signs, severe diarrhoea, or dehydration

• The horse has breathing difficulty

In practice, the mouth exam matters. Slaframine slobbers usually does not create ulcers or wounds inside the mouth. If the mouth is sore, damaged, ulcerated, or bleeding, look beyond slobbers. (MSD Veterinary Manual)

How Do Vets Diagnose Slobbers?

A vet usually starts with the history and physical exam.

They may ask:

• When did the drooling start?

• Did the horse change hay or pasture recently?

• Is there clover in the field or hay?

• Are other horses affected?

• Is the horse eating and drinking?

• Is feed or saliva coming from the nostrils?

• Are there mouth ulcers or injuries?

• Is the horse weak, feverish, colicky, or neurologic?

• Has the horse had access to toxins, chemicals, or unusual plants?

Diagnosis is often suspected when there is heavy salivation, recent exposure to affected forage, no oral lesions, and improvement after the forage is removed. Testing forage for slaframine or fungal contamination can help confirm exposure, but it is not always practical or necessary in straightforward cases. Merck notes that diagnosis can be based on characteristic signs and black patch on forage, with chemical detection helping confirm the diagnosis. (MSD Veterinary Manual)

If the horse has nasal discharge, swallowing difficulty, mouth lesions, weakness, fever, or only one horse is affected without a clear forage pattern, the vet will look harder for other causes.

When Is This an Emergency?

Call your vet urgently if your horse is drooling and has any of these signs:

• Feed or saliva coming from the nostrils

• Repeated coughing or gagging

• Difficulty swallowing

• Neck stretching or retching behaviour

• Distress or agitation

• Weakness or wobbliness

• Muscle tremors

• Collapse or inability to stand

• Breathing difficulty

• Fever

• Mouth ulcers, blisters, bleeding, or swelling

• Severe diarrhoea

• Colic signs

• Refusal to eat or drink

• Signs affecting multiple livestock species

• Suspected toxic plant, chemical, or contaminated feed exposure

If choke is possible, remove feed and water and call your vet. Merck specifically warns that horses with esophageal obstruction may continue to eat or drink, which can worsen signs. (Merck Veterinary Manual)

If weakness or difficulty swallowing is present, botulism and other neurological causes need urgent attention. That is not a “monitor until morning” situation. (MSD Veterinary Manual)

What Should You Do Right Now?

If your horse is drooling but otherwise seems bright, start with a calm, practical check.

1. Remove the suspect forage.
   Take the horse off clover-rich pasture or stop feeding the suspected hay.

2. Offer clean water.
   Heavy drooling can increase fluid loss, so water access matters.

3. Check whether your horse can swallow.
   Watch for feed or saliva coming from the nostrils, coughing, repeated swallowing, or distress.

4. Look carefully at the mouth if safe.
   Do not put your fingers deep in the mouth. Look for obvious ulcers, wounds, foreign material, swelling, blood, or foul smell.

5. Check other horses.
   If several horses on the same pasture or hay are drooling, a feed-related cause becomes more likely.

6. Inspect the hay and pasture.
   Look for clover, mouldy areas, dark patches, dust, damp bales, or unusual plants.

7. Monitor appetite, drinking, manure, attitude, and temperature.
   A bright horse with isolated drooling is very different from a dull horse that will not eat.

8. Call your vet if signs are severe, unclear, or not improving.
   Do not keep assuming slobbers if the pattern does not fit.

Most uncomplicated slaframine cases improve once the affected forage is removed, often within 24 to 48 hours, although some may take longer. (MSD Veterinary Manual)

How Is Slobbers Treated?

There is no specific antidote that owners need to give for a simple slobbers case.

The main treatment is removing the affected forage and providing clean water. Merck notes that no specific antidote exists for slaframine toxicosis, although atropine may control some prominent salivary and gastrointestinal signs in selected cases, and removal from contaminated hay is essential. (MSD Veterinary Manual)

Supportive care may include:

• Clean water

• Fresh, unaffected hay

• Moving to a different paddock

• Monitoring hydration

• Electrolyte support if advised by your vet

• Veterinary treatment if the horse is dehydrated, colicky, weak, or not eating

Do not give atropine, anti-inflammatories, sedatives, or oral medications unless your vet recommends them. If the horse is having trouble swallowing, oral dosing can be risky.

How Long Do Slobbers Last?

Most cases improve quickly after the horse stops eating the affected forage.

A typical timeline is:

• Signs can begin within hours of eating contaminated forage

• Drooling continues while the horse keeps eating the source

• Drooling usually improves after the source is removed

• Many cases settle within 24 to 48 hours

• Some may take up to several days depending on exposure and forage load

Merck reports recovery and return of appetite usually within 24 to 48 hours and up to 4 days after contaminated hay is removed. (MSD Veterinary Manual)

If your horse is still drooling heavily after changing forage, or if new signs appear, arrange a vet check. Time should make slobbers better, not worse.

Can Slobbers Affect Cattle or Other Livestock?

Yes. Slaframine toxicosis can affect large animals, including horses and ruminants, when they consume contaminated forage.

The signs may vary between species, but excessive salivation is the classic feature. In ruminants, the differential list can include important vesicular diseases, which is one reason drooling and mouth lesions in cattle should be taken seriously. (MSD Veterinary Manual)

For horse owners with mixed livestock properties, do not assume every drooling animal has the same harmless problem. Cattle, sheep, goats, and pigs with mouth lesions or vesicles may trigger a different level of disease concern and reporting requirements depending on location.

Common Mistakes Owners Make

Assuming all drooling is slobbers
Slobbers is common, but choke, oral injury, vesicular disease, botulism, and toxins can also cause drooling.

Not checking for nasal discharge
Feed or saliva from the nostrils is a major clue for choke.

Leaving the horse on the same pasture or hay
If slaframine is the cause, the signs may continue until the forage source changes.

Trying to force water or medication into the mouth
If the horse has trouble swallowing, this can increase the risk of aspiration.

Ignoring weakness or neurological signs
Drooling with weakness is not typical slobbers and needs urgent veterinary assessment.

Feeding damp or mouldy hay because “only one bale looks bad”
When in doubt, do not feed suspect forage. Hay is cheaper than a vet call, but only barely these days.

How To Prevent Slobbers

You cannot prevent every case, but you can reduce the risk.

Helpful steps include:

• Inspect hay before feeding

• Avoid feeding mouldy, dusty, damp, or suspicious bales

• Store hay in a dry, well-ventilated area

• Monitor clover-heavy pastures after wet or humid weather

• Rotate pastures where practical

• Avoid overgrazing

• Mow or manage heavily affected clover patches when appropriate

• Provide clean alternative forage if slobbers appears

• Watch whether multiple horses are affected after a forage change

• Keep records of which hay batch or paddock was linked to signs

Extension sources note that clover can be nutritionally useful but may occasionally become infected with fungus that causes slobbers. Removing or changing the offending forage is usually the most important management step. (Extension)

If slobbers keeps recurring on the same property, pasture composition and hay sourcing deserve a closer look.

Will Your Horse Be Okay?

Most horses with true slobbers recover well.

The outlook is usually excellent when:

• The horse is bright

• The horse can swallow

• There are no ulcers or nasal feed discharge

• The suspect forage is removed

• Water intake remains adequate

• Signs improve within 24 to 48 hours

The outlook becomes more guarded when drooling is caused by something else, especially choke, botulism, neurological disease, mouth trauma, vesicular disease, or serious toxic exposure.

The practical takeaway is simple: slobbers should improve when the feed source changes. If it does not, or if your horse looks unwell, stop calling it slobbers and get help.

FAQs

Can clover make horses drool?

Yes. Clover can be infected with a fungus that produces slaframine, a toxin that stimulates salivation. Red clover is a common source, but white clover and alfalfa can also be involved. (MSD Veterinary Manual)

Is slobbers contagious between horses?

No. Slobbers itself is not contagious in the usual horse-to-horse sense. However, multiple horses may drool at the same time if they are eating the same contaminated pasture or hay.

How long does it take for slobbers to stop?

Many horses improve within 24 to 48 hours after the contaminated forage is removed, although some cases can take up to several days. If drooling continues or the horse becomes unwell, call your vet. (MSD Veterinary Manual)

Should I call the vet if my horse is drooling?

Yes, if your horse has feed or saliva from the nostrils, difficulty swallowing, coughing, weakness, fever, mouth ulcers, colic signs, breathing trouble, or is not eating or drinking. If your horse is bright, swallowing normally, and several horses on the same clover-rich forage are drooling, you can remove the forage and monitor closely, but call your vet if you are unsure.

Can slobbers cause dehydration?

It can contribute to fluid loss if salivation is heavy or prolonged, especially in hot weather. Make sure your horse has constant access to clean water and monitor drinking, manure output, gum moisture, and general attitude.

Final Thoughts

Slobbers is one of those conditions that can look far worse than it usually is. A horse may drool buckets and still be bright, hungry, and perfectly capable of swallowing.

But drooling is a sign, not a diagnosis.

If the pattern fits slaframine exposure, remove the suspect forage, provide clean water, and monitor for improvement over the next 24 to 48 hours. If your horse has nasal discharge, difficulty swallowing, weakness, fever, mouth lesions, colic signs, or does not improve after the forage is changed, treat it as more than simple slobbers.

The safest approach is to respect the drool without panicking over it.

If you are unsure whether your horse’s drooling is simple slobbers, choke, toxicity, mouth injury, or something more urgent, ASK A VET™ can help you decide what to do next.