Botulism In Horses – Symptoms And Treatment

Last Updated on August 3, 2022

Knowing the most common symptoms of botulism in horses can be vital in ensuring a quick diagnosis of this disease. Botulism has a high level of fatality in horses and prompt treatment is vital to maximize the chances of a full recovery. Let’s find out everything you need to know about botulism in horses symptoms and treatment.

What Is Botulism In Horses?

Botulism in horses is a severe infectious disease that affects the neurological system. It is caused when Clostridium botulinum spores are either ingested or infect a wound. There is also a form of botulism found in falls where the spores produced toxins within the gastrointestinal tract.

The spores occur naturally within the environment, most commonly found in the soil. When environmental conditions are favorable, the spores are able to multiply to levels where they can cause toxic effects.

When a horse becomes affected by botulism, the toxin stops communication between muscles and nerves. This leads to reduced muscle strength and increased levels of muscle weakness. All animals can be affected by botulism, but horses seem to be particularly susceptible and a high level of fatality occurs when horses contract this disease.

How Do Horses Get Botulism?

There are three ways in which horses can contract botulism.

The most common cause of botulism in horses is when the horse consumes food or water which is contaminated with the toxin. Clostridial growth can only occur in anaerobic conditions, where oxygen is not present. The most common source of botulism in horses is haylage that has not been preserved or stored correctly.

Open wounds in horses can become infected with the bacteria that causes Botulism. This can occur in both young and adult horses, but fortunately is quite rare.

In young foals up to 8 months old, botulism can occur if the bacteria are ingested and able to grow in the gastrointestinal tract. This can affect any foal, but is more common in foals that eat a high grain diet. Foals with botulism experience high levels of muscle weakness and trembling, and are often referred to as ‘shaker foals’.

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What Are The Main Botulism In Horses Symptoms?

The main Botulism in horses symptoms include weakness of the muscles. Initially, this will most commonly manifest as reduced exercise intolerance, with the horse becoming tired and lethargic.

As the disease progresses, other signs may include muscle tremors, drooling of saliva, and reduced tongue strength. Over time progressive paralysis can occur, which will lead to difficulty swallowing and respiratory problems. Ultimately, this condition will lead to death due to respiratory paralysis and failure of the heart.

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How Is Botulism In Horses Diagnosed?

Diagnosing Botulism in horses can be difficult, as many neurological conditions have similar symptoms. A definitive diagnosis is often based on the clinical signs and excluding other neurological disorders, such as West Nile virus and tick paralysis.

Laboratory samples may not be conclusive as the levels of neurotoxin are often so low that they are barely detectable. It is normally easier to detect the source of the bacteria, from the horse’s environment or feed source. If an outbreak of botulism occurs in a group or herd of horses then this is the easiest way to reach a definitive diagnosis.

In some cases, the bacteria that cause botulism can be identified within samples of faeces taken from the gastrointestinal tract or swabs taken from wounds. Work is ongoing towards developing a more detailed definitive test for Botulism in horses, such as PCR testing or electrophysiological nerve testing.

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How Is Botulism In Horses Treated?

Botulism in horses is very difficult to treat, which is why this disease has a high mortality rate. The best chance of recovery is when the horse is given antitoxin in the very early stages of the disease. Unfortunately, this antitoxin is not widely available and can be very expensive.

Horses that are suffering from botulism also require intensive nursing care and supportive treatment to facilitate a full recovery. The neurological symptoms can be irreversible, and even if the progression of the disease can be halted the horse may never make a full recovery. Luckily, a vaccination against botulism in horses is widely available, so horse owners can do everything necessary to prevent the risk of their horse contracting this disease.

How Is Botulism In Horses Treated

Summary – Botulism In Horses

So as we have learned, being able to identify botulism in horses symptoms is vital to ensure treatment can be initiated quickly. Botulism in horses is a neurological disorder that causes weakness of the muscles. The main botulism in horses symptoms include exercise intolerance, drooling of saliva and muscle tremors.

We’d love to hear your thoughts on botulism in horses symptoms, diagnosis and treatment! Have you ever come across a case of botulism in horses? Perhaps you have some questions about how to reduce the risk of your horse contracting botulism? Leave a comment below and we’ll get back to you!


How Common Is Botulism In Horses?

Botulism in horses is not a common disease, but some horses are more risk of this condition than others. This includes foals that are fed a high grain diet, and adult horses that consume large amounts of haylage.

What Would Cause Botulism In Horses?

Botulism in horses is caused by spores that release toxins which damage the neurological system. These spores can enter the body through wounds or via the gastrointestinal tract.

How Do You Treat Botulism In Horses?

Botulism in horses requires intensive treatment and nursing care. The horse will need to be hospitalised in a veterinary clinic. This may include housing the horse in a padded stable to prevent injury from neurological problems.

Can A Horse Survive Botulism?

The mortality rate for horses suffering from Botulism is very high. Some horses do survive, but treatment can be expensive and long term. Horses that receive antitoxin against this disease have the best chance of a recovery.

Should I Vaccinate My Horse For Botulism?

Vaccination against botulism is the best way to prevent horses from contracting this disease. The spores that cause botulism live in the soil and can also contaminate haylage and hay. Water sources can also be contaminated with botulism.
It is virtually impossible to prevent your horse from being exposed to Botulism, so vaccination is the best chance to prevent them from contracting this disease.