Nystagmus (Unintentional Eye Movement) in Cats

What Is Nystagmus in Cats?

Nystagmus in cats is the involuntary rhythmic movement of the cat’s eyeballs. Nystagmus can be a normal reflexive movement, such as eye movement when a cat moves its head side to side (“doll’s eye reflex”).

When nystagmus occurs abnormally it is almost always associated with vestibular disease, a neurological condition where a cat experiences incoordination, falling, head tilting, and motion sickness, among other symptoms.

There are two types of pathologic nystagmus in cats:

• Jerk Nystagmus—The eyes move slowly in one direction away from an object and snap back quickly.

• Pendular Nystagmus—The eyes move with equal speed in both directions. This type of nystagmus is often seen in purebred Oriental cats (Siamese, Himalayan) and albino cats as a congenital defect in the visual pathway. Affected cats usually have other vision problems as well.

Nystagmus can also be categorized relative to head movement:

• Spontaneous—Eyes shift back and forth when the head is stationary. Eye movement can occur from side to side (horizontal), up and down (vertical), or circular (rotary).

• Positional—Eyes shift only when the head is moved in an unusual position (such as when the cat is placed upside down or flipped over on his back).

Nystagmus can be described as either conjugate (both eyes move in the same direction) or dysconjugate (each eye moves in opposite direction).

Nystagmus is not considered a medical emergency, but if your cat appears to be in pain or extremely uncomfortable, contact your veterinarian immediately.

Symptoms of Nystagmus in Cats

Nystagmus itself is a symptom of other conditions, particularly vestibular disease. But if not due to an underlying condition, nystagmus is not painful (though it can contribute to motion sickness).

In addition to nystagmus, a cat with vestibular disease may show symptoms such as falling or leaning to one side, head tilting, scratching at the ears, or stumbling, among many other signs.

Causes of Nystagmus in Cats

Nystagmus doesn't occur often in cats, but when it does, it almost always is due to vestibular disease.

Other related conditions include:

• Inner or middle ear infections—the most common cause of pathologic nystagmus

• Due to infection—feline panleukopenia (FIP), rabies, toxoplasmosis, or cryptococcosis  

• Idiopathic (unknown cause)­­—also known as feline vestibular syndrome, this condition often resolves without care

• Trauma

• Toxins – certain drugs like aminoglycosides or metronidazole (antibiotics) or chlorhexidine

• Nutritional (thiamine deficiency)

• Cancer

• Nasopharyngeal polyps

• Visual deficit—some lesions along the optic pathway

Certain Oriental breeds such as Siamese, Burmese, Himalayan, Persian, and Tonkinese are predisposed, and cats of any age can be affected.

How Veterinarians Diagnose Nystagmus in Cats

Nystagmus is often easily detected on physical examination alone. The veterinarian will identify the type of nystagmus present, which can help narrow down the possible causes. Categorizing the nystagmus helps determine which diagnostic testing to perform.

The vet often performs a neurological exam to identify any other neurological issues. Oral and ear (otoscopic) exams may be done, along with cultures to uncover possible infection. If bacterial infection is present, these tests can determine which antibiotic to prescribe.

The vet may recommend a myringotomy (surgical puncture of the ear drum) with a deep ear flush for both diagnostic sampling and treatment.

Other tests may be performed, such as:

• Baseline bloodwork, including a complete blood cell count

• Internal organ screening; urinalysis

• FeLV/FIV/FeLV and infectious disease PCR or titer testing. These are routinely performed to determine any underlying or associated causes

Other tests, such as advanced imaging (MRI and CT scan) or a cerebrospinal fluid tap, may be recommended to screen for infectious diseases, cancer, or inner ear infections. These are usually performed with a veterinary specialist.

Treatment of Nystagmus in Cats

Depending on the cause, some conditions can be cured where others can only be managed. Your veterinarian may recommend medication to reduce potential nausea and vomiting caused by nystagmus, such as chlorpromazine, meclizine, diphenhydramine or dimenhydrinate. 

Other conditions such as ear infections and FIP might require steroids, antibiotics, or antifungals.  Ear infections may require ear cleanings along with several weeks of antibiotics. Ear cleaning itself often requires anesthesia or heavy sedation.

Treatment options for cancer include surgery, chemotherapy, radiation, or a combination. Nasopharyngeal polyps are surgically removed.

Nystagmus cases without a clear underlying cause usually require minimal to no therapy, as clinical symptoms improve within a few days, with a complete recovery seen in a few weeks. 

Recovery and Management of Nystagmus in Cats

Recovery often requires two to four weeks but can vary depending on the cause. Fortunately, cats are skilled at compensating for issues with their vestibular system. Some symptoms may worsen temporarily following treatment, but improvement should be noticeable within a few days. 

During this time, be sure to keep your cat comfortable, away from other pets and away from stairs, pools, sharp corners, and other potential dangers as its balance and coordination may be affected. An e-collar or recovery cone may also be needed depending on their treatment and whether surgery is involved.

Although your cat may recover, some deficits such as a head tilt may persist. If your cat has nystagmus or one of the listed causes, symptoms can reoccur.

Unfortunately, for some conditions such as FIP, there is currently no approved treatment and the prognosis is poor, and some cancers may not be treatable. Pet parents may opt for palliative care or humane euthanasia, depending on the cat’s diagnosis. 

Prevention of Nystagmus in Cats

Nystagmus cannot be prevented, but having your cat examined at the first sign of nystagmus may opt for a better prognosis and speedier recovery. Keeping your cat indoors, routinely examined, and up to date on vaccines is crucial, along with good ear hygiene.