Involuntary Eye Movement (Nystagmus) in Cats

Key Takeaways

Nystagmus is the involuntary, erratic movement of the eyes. 

• Generally caused by conditions affecting the cat’s nervous or vestibular (balance) system

• Nystagmus can be a sign of life-threatening disorders and it is best to seek out veterinary care immediately after it is first observed

• Diagnostics may include physical examination, bloodwork, urinalysis, CT scans, and examination of the cerebrospinal fluid to determine the specific disorder

• Treatment varies depending on the condition causing the nystagmus, but can include surgery, medications, symptom management, or radiation

• Nystagmus is often seen alongside head tilting, circling, ataxia, and lethargy

A Closer Look: What is Nystagmus in Cats?

Nystagmus can be characterized into several categories depending on the nature of the eye movement. In general, the type of nystagmus does not reflect the severity of underlying disease. The general categories are:

Jerk nystagmus:

• Slow eye movements in one direction

• Rapid correction movement in the opposite direction

Pendular nystagmus:

• Small oscillations of the eyes without a change in speed

Positional nystagmus:

• Nystagmus that occurs only when the head is placed in an unusual position

Resting nystagmus:

• Nystagmus only when the animal is not moving and the head is in a normal position

Possible Causes

Nystagmus is associated with various disorders of the nervous and vestibular systems including:

• Poisoning, such as bromethalin, ethylene glycol, or stimulants • Infections of the middle and inner ear

• Hypothyroidism • Traumatic injury • Cancers, such as brain tumors and lymphoma

• Viral infections such as FeLV and FIV • Thiamine deficiency • Idiopathic vestibular disease

Risk Factors

If a cat has suddenly developed nystagmus, it is best to seek vet care immediately. Not all causes of nystagmus are life-threatening, but it is best to determine the underlying cause as soon as possible. Some underlying conditions associated with nystagmus are life-threatening and require prompt medical attention to improve health outcomes.

Pendular nystagmus is common in Siamese, Birman, and Himalayan cats. Affected cats display nystagmus from birth and are unlikely to have serious underlying disease.

Testing and Diagnosis

Diagnostics for nystagmus include:

• Physical examination • Blood work • Urine analysis • CT scan or MRI • Analysis of cerebrospinal fluid

• Bacterial culture analysis

Treatments will vary based on the condition associated with the instance of nystagmus but can include:

• Surgery • Radiation/Chemotherapy • Medication • Supportive care/symptomatic treatment

Similar symptoms

Nystagmus from side to side can be normal when the head is in motion. When the head is turned to the side, the eyes move rapidly towards the direction of turning, then return back to a central position.

Associated Symptoms

• Head tilting • Circling/pacing • Uncoordinated movement (ataxia) • Lethargy • Reduced appetite