Nystagmus (Unintentional Eye Movement) in Dogs

What Is Nystagmus in Dogs?

Nystagmus in dogs occurs when there is eyeball movement in a back-and-forth or circular motion that is out of the dog’s control.

Dogs (and humans) normally have nystagmus as they turn their head. This is called physiologic nystagmus, which helps hold the image the dog sees in place as they turn their head. The eyes are working in tandem with the dog’s vestibular system, which provides the dog with a sense of balance, knowledge of body position, and information about direction of motion.

If the dog’s head isn’t moving but they have nystagmus, the dog has a dysfunctional vestibular system causing abnormal (pathologic) nystagmus. Pathologic nystagmus can also occur with changes in position, such as when the dog is looking upward or lying on its side.

Types of Nystagmus of Dogs

Jerk nystagmus, which is when the eye moves slowly in one direction and quickly back in the opposite direction, is the most common form in dogs.

With pendular nystagmus, the eye movement occurs at the same speed in both directions. Pendular nystagmus is usually due to a congenital (at birth) condition.

When the eyes move side-to-side, it’s called horizontal nystagmus.

Abnormal eye movement in an up-and-down direction is vertical nystagmus in dogs.

Involuntary movement in a circular motion is rotary nystagmus.

Rarely, the eyes may each have a different direction of oscillation, such as the left eye moving horizontally while the right eye moves vertically. This is called disconjugate nystagmus.

Symptoms of Nystagmus in Dogs

Nystagmus often occurs along with changes to the pet’s balance or other neurologic signs.

Symptoms include:

• Uncontrolled and repetitive eye movements

• Head tilt

• Walking in circles

• Falling over or rolling

• Drunken gait (ataxia)

• Pupils not facing the same direction (strabismus) or uneven pupil size

• Lack of coordination or awareness of limb placement

• Loss of mental awareness

Causes of Nystagmus in Dogs

Pathologic nystagmus is often seen when there has been damage to the middle/inner ear or to the brain, both important components of the vestibular system.

Causes include:

• Inner or middle ear infection

• Middle ear surgeries or ear cleaning

• Congenital or hereditary abnormalities

• Tumors of the middle or inner ear or brain tumors

• Head trauma

• Strokes

• Inflammatory brain conditions, like granulomatous meningoencephalitis (GME)

• Infections affecting the brain such as distemper virus or neosporosis

• Medications and toxins like metronidazole, anesthetics, or marijuana

• Hypothyroidism (rare)

A common disorder in senior dogs with nystagmus is idiopathic peripheral vestibular disease. In this condition, nystagmus, head tilt, and disorientation occur without a known cause.

Dog breeds that can have a higher risk of congenital nystagmus include:

• Doberman Pinschers

• Cocker Spaniels

• German Shepherds

Other causes of nystagmus can occur in any breed.

Abnormal nystagmus warrants calling your veterinarian. If your dog is so disoriented that you’re worried they may injure themselves, consider visiting an urgent care veterinarian.

How Veterinarians Diagnose Nystagmus in Dogs

Your veterinarian can diagnose nystagmus through physical examination. What they won’t be able to do through examination alone is determine the exact cause.

Diagnostics should include a neurologic examination, which involves testing reflexes, watching your pet walk, and other ways to determine which part of their vestibular system is affected. They will also want to perform an ear examination. A torn or swollen eardrum may indicate a middle or inner ear infection.

In some cases, your veterinarian may recommend puncturing the eardrum (myringotomy) to get a sample for culture from the middle ear. Your pet will need to be anesthetized for this.

If your veterinarian suspects a middle or inner ear condition, they may recommend you pursue a CT scan. Usually, CT scans are performed at specialty clinics and veterinary hospitals using sedation or general anesthesia.

If they’re concerned that the brain may be affected, the veterinarian is more likely to recommend an MRI and analysis of the fluid that surrounds the brain (cerebrospinal fluid analysis). MRIs and cerebrospinal fluid collection are also generally performed at specialty clinics and veterinary hospitals using general anesthesia.

Make sure to let your veterinarian know:

• If you’ve recently cleaned the dog’s ears or used medications for the ears

• Any new medications your pet is taking

• If your pet may have consumed marijuana

Treatment of Nystagmus in Dogs

Nystagmus itself can’t be cured, as it is generally a symptom of an underlying condition. If an underlying cause is determined, such as an inner ear infection, treatment is aimed toward resolving the underlying condition, which should resolve the nystagmus.

Often, nystagmus occurs without a known cause as part of idiopathic vestibular disease. Treatment is more supportive, focused on altering the environment to prevent self-injury and providing anti-nausea medications like maropitant citrate.

Dogs with brain disorders usually don’t do as well as ones who have idiopathic vestibular disease or a condition affecting their ears. Treatments vary widely depending on the type of condition, such as a brain tumor or an infection.

Recovery and Management of Nystagmus in Dogs

With nystagmus occurring as part of idiopathic vestibular disease, improvement usually happens within one or two weeks.

Nystagmus may resolve on its own within several weeks. However, if the underlying cause is not resolved, the symptoms may continue.

With nystagmus your pet’s balance is altered, so make sure you’re keeping them safe from accidentally injuring themselves. This means keeping them away from stairs, off porches, and away from other fall risks. Consider keeping them confined in a well-padded area. Placing them in a dark room, though it may sound beneficial, can worsen their balance as it impairs their sense of orientation.

Conditions causing nystagmus can recur. One episode of nystagmus does not make your dog immune to additional episodes.

Prevention of Nystagmus in Dogs

Most cases of nystagmus in dogs aren’t preventable. However, you should use caution when cleaning ears, as vigorous ear cleaning can lead to vestibular dysfunction and nystagmus.

Speak with your veterinarian before placing any medications in the ears, even if it’s a medication you have used before.

Ear infections can spread to the middle or inner ear.  It’s important to get your dog’s ear infections taken care of in a timely manner.