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Home > Ask A Vet > Sudden Onset Ataxia in Horses: Vet Answer (Definition, Causes, & Treatment)

Sudden Onset Ataxia in Horses: Vet Answer (Definition, Causes, & Treatment)

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Dr. Joe Mallat

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You’ve noticed that your horse’s gait isn’t quite right. You might have detected this either under saddle or by watching them move around a paddock. It could be caused by lameness, but it could also be ataxia.

First, let’s define ataxia. Ataxia refers to wobbliness caused by a neurological problem. Lameness, on the other hand, refers to a change in gait or “limp” and is usually caused by pain of the muscles, tendons, or bones. If a vet has told you that your horse has ataxia, it can be harder to understand than something like a sore muscle, which most of us are familiar with.

This article will explain ataxia in horses—what it means, what it looks like, and what can be done to fix it.


What is Ataxia in Horses?

Ataxia is defined as the incoordination of voluntary movement. Put simply, when your horse decides to walk or trot, their gait appears clumsy and uncoordinated. Ataxia is neither a disease nor a diagnosis—it is purely a sign of neurological disease. A limp is a sign of pain, and wobbliness is a sign of ataxia. A number of neurological diseases can cause ataxia.

A neurological disease refers to a disease in the brain, inner ear, or spinal cord. While brain and inner ear diseases are certainly possible in the horse, they are extremely rare. The vast majority of horses with ataxia have spinal cord disease. But what is spinal cord disease, and why does it cause ataxia?

Think of the spinal cord as the circuitry that connects the legs to the brain. It transmits information picked up by the nerves, and this connection between legs, spinal cord, and brain allows the horse to walk in a controlled, coordinated fashion. If this connection is lost, the legs are required to “figure it out” for themselves, with no input from the brain. This results in an abnormal, wobbly gait.

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What Are the Signs of Ataxia in Horses?

Some common signs of ataxia in horses include:
  • Wobbliness
  • Dragging or scuffing of the feet
  • Swinging legs to the side when walking
  • Tripping or falling over
  • Swaying of the trunk and neck
  • Difficulty walking in a straight line
  • Laying down with difficulty rising

A note here on how to distinguish lameness from ataxia—there are two differences. Firstly, lameness is usually associated with pain—a sore foot or muscle makes your horse reluctant to put weight on that leg, causing a limp. Ataxia, on the other hand, is usually not painful. Secondly, lameness is consistent or repeatable. If you walk your horse up and down in a straight line several times, the limp will look very similar each time. Ataxia, on the other hand, is inconsistent. The gait changes all the time and does not have an obvious pattern.

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What Are the Causes of Ataxia in Horses?

This article will not explore the causes of ataxia associated with the inner ear or brain disease, as they are very rare. If your vet suspects one of these causes, they’ll guide you through the diseases and diagnostic options. Spinal cord problems are much more common, and there are five main causes to discuss:

1. Wobblers Syndrome

Wobblers Syndrome is a slang term used for horses with cervical stenotic myelopathy, though there are a few other names for this disease. It refers to a narrowing of the vertebrae of the neck, which compresses the spinal cord in this region. Wobblers Syndrome typically affects either:

  • Young, fast-growing horses, such as a yearling or weanling Thoroughbred colts
  • Warmbloods, Thoroughbreds and Quarter Horses older than 4 years of age

Unfortunately, diagnosis of Wobbler horses is difficult, and the disease is usually progressive. We don’t fully understand what causes the vertebrae to become narrow and malformed, but it’s likely to do with genetics, diet, exercise, and injury.

Horse with wobbly legs
Image By: GoDog Photo, Shutterstock

2. Infection

Infection with different bugs can cause inflammation of the spinal cord, and ataxia is the consequence. There are a few infectious causes of ataxia, and the specific viruses, bacteria, or protozoa vary depending on which part of the world your horse lives in. Some common infections include:

  • Equine herpesvirus 1
  • West Nile virus
  • Protozoan parasite Sarcocystis neurona. This is most common in North America. You may hear this referred to as equine protozoal meningitis or EPM.
  • Hendra virus in Australia

Horses with a fever are more likely to have an infectious cause of their ataxia, but this is not always the case. Diagnosis and treatment of infections depend on your horse’s symptoms and geographic location.

3. Trauma

Falls, collisions, or accidents can all cause ataxia. Fractures or dislocations of the vertebrae will often cause damage to the spinal cord that these bones “house”. These injuries are very significant. Unfortunately, the fall is often not witnessed by horse owners. Diagnosis is possible with X-rays, but treatment can be very difficult.

Belgian warmblood purebred horse
Image By: Lucia L, Shutterstock

4. Toxins

A long list of toxins can cause ataxia in horses. This includes:
  • Stinging nettle plants in some parts of the world
  • Heavy metals such as lead
  • Monensin, which is found in some cattle feeds
  • Many other plants

5. Stroke or tumor

Strokes occur when blood cannot get to the brain or spinal cord due to the blockage of an artery. These are rare in horses, though they are very difficult to diagnose.

Tumors can compress the spinal cord. These are more common in older horses, and the onset of ataxia is not as sudden as it is with all of the causes outlined above. Melanoma and lymphoma are tumors that can cause ataxia in horses.

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How Do I Care for a Horse with Ataxia?

Vet examining horse
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 There are very few home remedies for a horse suffering from ataxia, and care depends on a specific diagnosis. There are three steps to follow:

  1. Call your veterinarian. They will give your horse a full checkover, followed by a lameness and neurological examination.
  2. Keep your horse somewhere safe until the vet arrives. If your horse appears wobbly on their feet, a paddock may be safer than a stable.
  3. Do not ride your horse. Riding ataxic horses can be very dangerous.

Related Read:

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Can Horses with Ataxia Recover?

The answer to this depends on the underlying cause. Generally speaking, horses suffering an infection or toxicity can recover with appropriate treatment. Horses suffering from Wobblers syndrome, a bad traumatic accident, or a tumor are less likely to recover. Unfortunately, if the ataxia is severe enough, some horses will need to be humanely euthanized due to the risk they pose to both themselves and their handlers. Your vet will be able to guide you through the prognosis of your horse making a recovery.

Can Horses with Ataxia Be Ridden?

Riding horses with ataxia is dangerous and not recommended under any circumstances. Horses with ataxia are much more prone to falling over, posing a risk to both themselves and you as the rider. Some horses with mild ataxia are able to live comfortably in a paddock but are not candidates for riding.


Ataxia in horses will often appear suddenly, but it can progress slowly over time. Since it is a neurological problem (as opposed to a muscle/tendon problem), the treatment of ataxia in horses varies. If you think your horse is ataxic, stay calm and contact your veterinarian. Your vet will discuss with you the possible causes, as well as any further tests that need to be run.

Featured Image Credit: Jaco Wiid, Shutterstock

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