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Foaming at the Mouth in Horses: Understanding the Causes and Symptoms

Foaming at the Mouth in Horses: Causes and Symptoms

As a horse owner, have you ever been concerned when you see your horse foaming at the mouth? Foaming or lathering in horses may indicate a variety of different conditions, some mild and others more serious.

In this article, we will examine the possible causes of a horse foaming at the mouth. We will also discuss the diagnosis and treatment for each condition.

Protein as a Cause

One possible cause of foaming is the presence of a protein called latherin. Horses produce latherin in their sweat and saliva, and it works to regulate their body temperature.

The function of latherin in digestion is also thought to be an essential role. When mixed with air or friction, latherin can create a soapy, slippery solution that may cause foaming in some horses.

Eating, Drinking, and Chewing

Another common cause of a foaming mouth in horses is hypersalivation. Horses produce a significant amount of saliva, particularly while chewing their food.

Some horses can produce so much saliva that it spills out of their mouth and creates foaming. Hypersalivation can occur for various reasons, such as being in hot and humid conditions, dental problems, or drinking excessively.

Bits as a Cause

A horse may also foam at the mouth when wearing a metal bit. A bit can cause discomfort or pain that leads to hypersalivation or lathering.

This condition is prevalent in dressage horses where the rider aims to relax their horse. Using a hard hand or poor riding form may also cause a horse to foam at the mouth.

If a horse feels stressed or anxious about its rider, it may excessively produce saliva.

Sign of Relaxation

In some cases, foaming may be a sign of relaxation. When a horse is relaxed, it may naturally produce more saliva than usual and appear to be foaming at the mouth.

The practice can be common with performance horses, particularly those who get trained in dressage. Many owners may consider it a sign of their horse cooperating with them.

Sign of Stress or Exertion

On the other hand, if your horse is foaming at the mouth, it may indicate stress or exertion. A horse is a flight animal, and they are prone to experiencing anxiety, which can make them produce more saliva or foam at the mouth.

Overexerting a horse by challenging it beyond its physical abilities can also induce foaming.

Clover Slobbers and Other Illnesses

Clover slobbers are a type of hypersalivation that occurs when a horse ingests a fungus found in clover. The fungus causes the horse to salivate excessively, which can create foaming or lathering.

There might be other diseases that can cause foaming, such as Vesicular Stomatitis and Rabies.

Mouth Injuries and other Dental Issues

A horse may foam at the mouth if its mouth suffers an injury or has an ulcer. Dental problems, such as damaged or lost teeth and other tooth-related diseases, can also cause foaming in horses.

Owners must ensure that their horses receive regular dental checkups by a qualified equine dentist to prevent such dental issues. Choking, Foreign Body in the Throat, and Bacterial Infections

If a horse accidentally swallows a foreign object, such as a piece of hay or straw, it may lodge in the horse’s throat and cause foaming.

Choking can lead to more severe problems and may need veterinary attention. Bacterial infections, such as Equine Grass Sickness and wooden tongue are also known to cause foaming in horses.

Toxic Substances

The ingestion or consumption of poisonous substances, like heavy metals and organophosphate poisoning, can cause foaming in horses. Symptoms vary, but foaming at the mouth may be one of the signs that poison is present in their system.


Foaming or lathering in horses is not uncommon, but it is essential to identify the cause quickly. Many different factors can cause a horse to foam at the mouth, ranging from minor issues to severe illnesses.

As a responsible owner, you must keep a keen eye on your horse and make sure it gets regular check-ups with a veterinarian. By considering their health needs seriously, you can prevent a range of health issues and keep your horses happy and healthy.

3) Bits and Foamy Mouths: The Role of the Bit

A well-fitting bit is an essential tool for horse trainers to communicate with their horse. While bits can be made from a range of materials, metal bits are most commonly used.

While it is widely accepted that bits are harsh and can cause pain in the horse’s mouth, a bit is an essential tool for a horse’s training. A bit forms a critical part of the bridle and helps a rider to control the horse’s movement.

Breaking Suction of Lips

One common issue with bit usage is that if it is not correctly placed, it can create a vacuum effect in the horse’s mouth that leads to excessive salivation. This is due to the suction created when the bit comes in contact with the lips.

When the lips touch the bit filling the mouth space, the air gets trapped, causing one to produce more saliva. By breaking the suction of the horse’s lips and allowing the air to mix with the saliva, the foamy mouth condition can be prevented.

Excess Saliva and Churning Foam

Horses have a unique chewing motion that involves grinding food between their teeth. As a result, they produce a lot of saliva that mixes with the food to aid digestion.

During this process, a horse may chew on the bit and produce excessive saliva that leads to foaming at the mouth. The foaming from bit play is a typical sign observed in performance horses like dressage.

Horse riders and trainers regard it as a sign that the horse is relaxed and comfortable working in a bit.

It’s essential to keep in mind that the amount of foam produced by each horse may vary, depending on the breed, temperament, and stage of training.

Some horses may foam more than others, even when they are not relaxed, and vice versa.

Sign of Relaxation and Stress

Foaming at the mouth may indicate more than just hypersalivation.

It is essential to keep an eye on the foaming pattern, amount, and color to diagnose the underlying cause. Observing the horse’s physical expression and temperament, overall mood, and body language can help identify the foaming pattern.

Happy Foam in Dressage

In dressage, ‘happy foam’ is used to describe white foam around the horse’s mouth, which is regarded as a sign of relaxation. The foam created from bit play during dressage movements is a desirable indication of performance.

Trainers and riders celebrate the white foaming around the jacket as a proud, collaborative moment between them and the horse.

Tense and Stressed Horses

In contrast, excessive foaming in a more tense and anxious horse may indicate that the horse has worked to their limit. Foaming around the mouth may turn brown and indicate that the horse is overexerting itself and experiencing fatigue.

Tense and stressed horses may produce excessive amounts of white or brown foaming, requiring a more trained professional to diagnose the underlying condition.

Importance of Observing Individual Horses

It is vital to observe the individuals because every horse is different. Each horse will foam differently; sometimes, there may be no foam even though the animal is relaxed.

Observing horses during various activities and comparing the amount, color, and pattern of foam can help identify any changes or unique signatures. A horse may foam more or less depending on the work plans or how they feel.

Horse owners should work closely with trainers and veterinarians to determine if the foaming is a real cause for concern. It is also essential to note that excessive foaming in horses can be a side effect of some medications and modes of treatments.

Therefore, veterinarians should always be consulted before administering medications to horses.


Foaming at the mouth in horses is a common condition that can occur due to different factors. Bit play is the leading cause of excessive salivation and foaming in horses, but it can also be due to other elements.

White foam around the mouth in a dressage horse can indicate relaxation, while brown foam can indicate excessive exertion. Whether a horse foams or not is a trivial matter; the real issue is why it’s happening.

Therefore, it is essential to work closely with trainers and veterinarians to determine the underlying cause and appropriate treatment to ensure that the horses remain calm, healthy, and happy. By closely examining the individual horse, the owners can provide the best care for their companion.

5) Clover Slobbers and Other Causes of Foaming

Foaming at the mouth in horses is not always a result of bit play. Multiple underlying conditions may be leading to excessive salivation and foaming in horses, which can be a cause for concern.

Clover Slobbers

Clover slobbers is a condition that occurs when horses feed on clover infected with the Rhizoctonia fungus. As a result, the horse can experience hypersalivation and end up foaming at the mouth due to the excessive saliva production.

This white foaming is a clear sign of clover slobber syndrome, and although it can look alarming, it typically clears up quickly.

Choking and Foreign Bodies

If a horse accidentally inhales foreign material while grazing or feeding, it can quickly become lodged in the throat. This blockage can limit airflow or lead to intense coughing and, in some cases, foaming at the mouth.

Coughing can cause irritation leading to extra saliva production, further contributing to excess foaming and white bubbling.

Dental Injury or Disease

Dental injuries and diseases can also cause foaming. Horses with dental issues often have difficulty chewing their food, leading to excessive salivation and foaming.

It is essential to keep an eye on your horse’s dental hygiene and ensure that they receive routine dental checkups from a qualified equine dentist to avoid such issues.

Vesicular Stomatitis and Other Diseases

Vesicular Stomatitis is a rare but serious illness that can cause foaming in horses. This disease leads to the formation of blisters around the horse’s mouth, which can lead to swelling and excessive salivation.

Horses that are infected with Vesicular Stomatitis may excessively foam and produce brown saliva as the virus progresses.

Toxic Substances and Bacteria

The ingestion of toxic substances or bacterial infections caused by contaminated feed or water can lead to excessive foaming in horses. Examples of toxic substances include heavy metals, fertilizers, and pesticides.

Contamination from bacteria can happen due to the presence of harmful bacteria or fungi, leading to specific conditions like Wooden Tongue or Equine Grass Sickness. Symptoms typically include excessive salivation and foaming around the mouth.


Foaming at the mouth in horses is not always due to excessive bit play. Severe situations like Vesicular Stomatitis or dental issues like infected teeth or gum disease, when left untreated, can cause significant harm to horses.

Though excessive salivation and white foaming are common with horses, the cause behind the foaming can indicate the seriousness of the situation. It is essential to work closely with the equine dentist and the veterinarian to ensure that the horse remains calm, healthy, and comfortable.

Foaming at the mouth in horses can occur due to various reasons, including bit play, dental issues, diseases, and toxic substances. Owners and trainers must observe the individual horses closely and identify the cause behind the excessive foaming.

It is essential to work closely with the equine dentist and veterinarian to provide the appropriate treatment and care for the horse. If left untreated, dental issues or illness can cause significant harm to horses.

By understanding the various causes of foaming and taking the necessary steps, owners can keep their horses healthy and comfortable.


1. Can bit play cause foaming in horses?

Yes, bit play can cause foaming in horses due to excessive salivation.

2. What other causes of foaming are there besides bit play?

Other causes of foaming in horses include clover slobbers, choking, dental issues, diseases, and toxic substances.

3. How can owners prevent dental issues in horses?

Owners can prevent dental issues in horses by practicing regular dental checkups with a qualified equine dentist.

4. Can Vesicular Stomatitis cause foaming in horses?

Yes, Vesicular Stomatitis can cause excessive foaming and the formation of blisters in horses.

5. What should owners do if their horse is foaming excessively?

Owners should observe their horses closely and seek the advice of an equine dentist or veterinarian if they believe the foaming is excessive and indicates an underlying issue.

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