Why Do Horses Foam At The Mouth

Why Do Horses Foam At The Mouth?

If you’ve ever seen a horse in action, you’ve probably noticed a frothy substance around the horse’s mouth. This is very common in horses that are being ridden.

But why do horses foam at the mouth? Is it a sign of distress, or is it perfectly normal?

Here’s a quick guide that’ll break down the reasons behind this occurrence and give you some guidance on when it might be something to worry about.

What is the Foam Around a Horse’s Mouth?

The foam around a horse’s mouth is just the horse’s saliva. When a horse is ridden, it produces more saliva. This saliva then mixes with the air to create the foam you see. Most of the time, this is seen as a positive thing, showing a rider that the horse is relaxed. But, there are cases where excessive foam or froth can indicate other issues.

This foam can also appear around the horse’s chest or saddle area.

Horse foaming at the mouth and chest

Should a Horse Foam at the Mouth?

Absolutely. A certain amount of foaming at the mouth is even sought after. In some equestrian disciplines, riders even try to work up a lather around the mouth before riding. It shows that the horse is producing saliva and is comfortable, especially with its bit. But, if a horse starts to produce excessive saliva, you may have to examine it to see what’s going on.

Why Do Horses Froth at the Mouth?

When a horse foams at the mouth, there are many possible reasons. So, here’s a summary of the most common causes:

Your horse is relaxed

When a horse is happy, it’ll become more relaxed and enjoy its work. This relaxation can often lead to foam at the mouth. ‘Happy foam’ is a good sign that the horse is comfortable, especially with its bit. It also shows that the horse is producing saliva, which is needed for the bit to move smoothly in the mouth.

Relaxed horses chew and work their bit which creates foam. Do note that not all horses will foam at the mouth when they’re relaxed. Also, some horses produce more sweat than others.


A tense horse is likely to produce much more saliva than one that’s relaxed, this then leads to foaming at the mouth. Horses generally become tense through physical stress, like overexertion during an intense workout. But, they’re also widely known to experience emotional stress, brought on by fear or anxiety.

Even changes in the horse’s environment, like a new stable or a new rider, can lead to stress. This is why monitoring your horse’s behaviour and body language for identifying signs of stress and quickly addressing them. Regular exercise, a consistent routine, and a calm, reassuring approach can help alleviate stress in horses.


Rabies is a rare disease but it should always be taken seriously. Rabies can cause horses to drool excessively because it affects the nervous system. Besides foaming at the mouth, rabies can lead to a variety of symptoms, like behavioural changes and difficulty swallowing. Rabies is usually transmitted through the bite of an infected animal and it’s almost always fatal once symptoms show.

Getting your horse a rabies vaccine is the best way to protect it from the disease. It’s even considered a core vaccine by horse experts. If your horse is foaming at the mouth and showing other symptoms of rabies, you have to contact your vet immediately as rabies in horses is invariably fatal.


Choking is another very common reason why a horse’s mouth might start foaming. It happens when a horse’s oesophagus is blocked, usually by food. If your horse is unable to swallow, saliva will start to build up in the mouth and overflow, often appearing as foam. Choking is a very serious condition that requires immediate veterinary attention.

To prevent choking, make sure that your horse’s food has enough moisture. You should also avoid feeding it large amounts of dry food or large apples or carrots that can get stuck in its throat.


Another cause is saliva called Latherin. Latherin is a type of protein that’s found in horse sweat and saliva. It helps horses digest dry forage and also creates the foam you see when a horse is sweating or working hard. Latherin is like a detergent, breaking the surface tension of water. This allows sweat to spread across the horse’s coat, so it can cool down.

When horses are ridden, the bit stimulates saliva production and the bit moving in the horse’s mouth is what makes the saliva foamy. Some riders even give horses a sugar cube before a ride to stimulate the salivary gland.

Racehorse foaming at the mouth


Slobbers, also known as ‘dew poisoning,’ is a condition caused by a fungus that grows on red and white clover. When horses eat an infected clover, the result is them producing excessive saliva, leading to a foamy mouth. Slobbers usually aren’t harmful to the horse, but it can be messy and unpleasant to deal with.

You can prevent slobbers by checking your pasture for any red and white clover that produces brown or grey spots. Another thing to consider is limiting your horse’s grazing time during wet and humid conditions, as this is when the fungus is most prevalent.

A tense rider

When a rider isn’t relaxed and is tense, a horse can become tense too, leading to foaming at the mouth. The tension in the rider’s body can be transferred through the saddle and the reins to the horse, making it become anxious and stressed.

This can stimulate the production of saliva and lead to foaming. To avoid this happening, riders should work on staying in a relaxed and balanced position in the saddle, as well as making soft and steady contact with the reins.

An ill-fitting or incorrectly placed bit

An ill-fitting or incorrectly placed bit can cause a horse to produce excess saliva as a response to the discomfort. The bit is an important piece of riding equipment, and it’s essential that it fits the horse correctly and is comfortable. The bit, bridle, and reins all work together to give a rider control over a horse’s head.

Regular checks and adjustments can ensure the bit is suitable and correctly placed.

Dental issues

Dental issues, like missing teeth, excessive plaque, or too much tartar, can cause a horse to produce excess saliva. This extra saliva can then cause your horse’s foaming at the mouth. Always ensure that your horse goes for regular dental check-ups to help prevent these issues.

Horses with dental problems often struggle to chew and frequently drop food from their mouths. They may also show signs of discomfort while eating or when the bit is in their mouth. Regular dental care is important for having a healthy and happy horse.

A mouth injury

This is also another area where dental check-ups are important. A mouth injury, like a cut or a bit that breaks, can cause mouth foaming. The pain and discomfort from the injury can stimulate the production of saliva. If you see your horse’s mouth foaming and suspect an injury, consult a vet.

Toxins building up

Heavy metals and other organic chemicals in the soil can build up in a horse’s body over time, leading to heavy metal toxicity. This can cause many symptoms, with excessive drooling in a previously healthy horse being one of the most common.

If you suspect your horse has been exposed to heavy metals, it’s important to consult a vet. Test your soil as often as possible to identify the presence of heavy metals and other toxins in your horse’s environment.

Bacterial infections

Bacterial infections can cause inflammation and sores in a horse’s mouth, leading to the production of excess saliva and, in turn, causing foaming. While many bacterial infections are rarely fatal, they can make the horse uncomfortable and cause it stress. They can also be highly contagious.

If your horse is foaming at the mouth and showing other signs of infection, separate it from any other horses and contact your vet.

Vesicular stomatitis

Vesicular stomatitis is a viral disease that’s known to make horses foam at the mouth. Vesicles, or blisters, in the mouth and on the lips, tongue, and muzzle are signs of the disease. The discomfort caused by these blisters stimulates the production of saliva, leading to a foamy mouth.

Vesicular stomatitis can also result in lameness if blisters form on the coronary bands. It’s also highly contagious, so keep this in mind if you have more than one horse.

Equine viral arteritis

Equine viral arteritis or EVA is another contagious disease of horses that can cause a variety of symptoms, including foaming at the mouth. EVA is caused by a virus that affects the horse’s blood vessels, leading to inflammation and damage.

Symptoms can include fever, depression, swelling of the limbs, and red or grey spots in the mouth and on the tongue. The inflammation in the mouth can cause the horse to produce excess saliva, leading to a foamy mouth.

EVA is rarely fatal but it can cause serious issues like pregnancy complications for mares. Vaccination is the most effective way to prevent EVA. If your horse is showing symptoms of EVA, consult a vet for diagnosis and treatment.

What to Do When a Horse is Foaming at the Mouth

When your horse is foaming at the mouth, the first thing you should do is identify what could be causing it. This means looking for symptoms that indicate a health issue.

For example, if your horse has a sudden change in behaviour, like unusual aggression or not eating, it may be a sign that there’s something else going on. It could also be something as simple as a stick or other foreign body stuck in the horse’s mouth.

Remember that consulting a vet is usually best when you’re unsure about a horse’s condition. The vet bills may hurt a little, but rather be safe than sorry.

How to Stop Your Horse Foaming at the Mouth

Preventing foaming at the mouth largely depends on what’s causing it. For example, if stress is the cause, you can simply look for ways to help your horse relax. Changing your riding style, giving more training, or making changes to the horse’s environment can all help a horse relax.

If a health issue like a dental problem is causing the foaming, then consult a vet immediately, as this is generally something that can’t be fixed without the necessary skills. We would also recommend scheduling regular check-ups to catch any issues before they become worse and, ultimately, prevent excessive foaming.


Is vesicular stomatitis fatal?

Luckily, vesicular stomatitis is rarely fatal. But, it can make a horse uncomfortable and cause it distress. Do note that this condition is highly contagious, so it’s important to isolate affected horses by it and seek veterinary treatment, as soon as possible.

When should I consult a vet about a horse foaming at the mouth?

You should talk to a vet if your horse is producing excessive foam, especially if you notice other symptoms like changes in behaviour, difficulty eating, or signs of distress.

Can foaming at the mouth affect a horse’s performance or behaviour?

Yes. A horse’s mouth foaming can be a sign of stress or it being uncomfortable. This can definitely impact a horse’s performance and behaviour. Remember that a small amount of foam is usually normal and is regularly seen as a positive sign that the horse is relaxed and unbothered by its bit.

What is hypersalivation in horses?

This is when a horses produce an abnormal amount of saliva. Horses generally produce around 10 to 37 litres of saliva a day, so anything more than this may be a cause for concern.

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