A mixed-breed dog with sectoral heterochromia.

Heterochromia (Irregular Iris Pigmentation) in Cats and Dogs

Overview of Heterochromia in Cats and Dogs

Heterochromia, also known as binocular heterochromia and heterochromia iridis, is a condition that results in irregular pigmentation of the iris. In layman terms, this condition results in two different colored eyes. The iris is the colored tissue in the front of the eye that surrounds the pupil and gives the eye its color. Humans commonly have blue, brown, green, or hazel irises. The function of the iris is to regulate the size of the pupil by allowing more or less light to enter the eye.

Iris pigmentation is typically uniform, though irregularities, like one eye being a different color or more than one color, occur with conditions like heterochromia. These irregularities can be present at birth or acquired later in life as a result of a variety of diseases.

What to Watch For

Heterochromia appears as iris pigment variations in one eye or a difference from one eye to the other. Examples include an iris that is half brown and half blue, or one blue eye and one brown eye.

If your pet is showing new signs of heterochromia or has any abnormal symptoms, call your veterinarian or closet veterinary emergency clinic.

Diagnosis of Heterochromia in Cats and Dogs

Heterochromia is diagnosed by examination of the eye that shows pigment changes in the iris. If it’s congenital, it may be a coincidental finding during a routine examination. However, if it’s acquired, diagnostic tests are recommended to determine the underlying cause.

Tests may include:

Treatment of Heterochromia in Cats and Dogs

In cases of congenital heterochromia, no treatment is needed. In cases of acquired heterochromia with active signs of inflammation or ulceration, treatment may include the following:

Home Care

For pets with active inflammation, administer all medications as directed. For instructions on how to medicate the eye, please read How to Administer Eye Medication to Your Dog.

Monitor your pet closely for signs of worsening ocular pain or inflammation. Call your veterinarian immediately if you see changes or your pet is rubbing at the eye. Scratching, pawing, or rubbing can cause additional damage. An e-collar may be recommended.

Preventive Care

Prevention tips for developing acquired heterochromia include:

Prognosis for Dogs and Cats with Heterochromia

For dogs and cats with congenital heterochromia, the prognosis is excellent, as this is a normal clinical finding. The prognosis for acquired heterochromia depends on the underlying cause.