Feline Iris Hyperpigmentation: Melanosis in Cats

Hyperpigmentation of the iris is a relatively uncommon condition in cats. The iris is the portion of the eye surrounding the pupil and containing color. In the case of feline iris hyperpigmentation, certain parts of the iris change color and reflect light differently from the normal spots on the eye. This condition can be generally benign, as in the case of melanosis, or it may be cause for alarm. The malignant and more dangerous cause of hyperpigmentation in the feline iris is melanoma. While melanosis is typically less of a concern, it can still lead to loss of vision and other health effects.

The Process of Melanosis in Cats

Melanosis is a condition in which certain spots on one or both eyes change color suddenly. You may notice that your cat's eye appears to be discolored in a certain area, or that his two eyes no longer seem to match. Melanosis generally occurs in one eye only, although it can happen in both eyes. In the case of melanosis of both eyes simultaneously, your pet's eyes will be asymmetrical.

Dangers of Melanosis

Melanosis is typically a benign and relatively harmless condition. It may affect the appearance of your cat's eyes, but is unlikely to alter your pet's vision in any way. Melanosis does not cause any distortion to the surface of your pet's eye or lead to any obstruction that covers all or some of his eye.

That is not to say, however, that melanosis is always a harmless occurrence. In some cases, melanosis of one or both eyes may lead to glaucoma in that eye. Glaucoma is characterized by high amounts of pressure on the eye that may distort your pet's vision and prove to be very painful.

Melanosis can also be confused with melanoma. An ocular melanoma is a form of feline cancer that obstructs vision and typically spreads rapidly. Left untreated, a melanoma can destroy your pet's vision in one or both eyes and spread to other parts of his body as well, posing a significant health risk. One of the symptoms of melanoma is iris hyperpigmentation. For this reason, it is crucial that you not ignore a change in your pet's eye color. Take him to a veterinarian for examination and to determine that the cause of the hyperpigmentation is not a form of cancer. While most melanosis cases are left untreated (unless there is a danger of glaucoma), melanomas must be surgically removed in order to prevent the cancer from spreading.

Check for signs of melanosis periodically as you brush or pet your cat. Familiarize yourself with the color and natural spots on his eyes, and be aware of any changes that occur to one or both of them. If you do detect any hyperpigmentation, don't hesitate to take your cat to the vet for further inspection and testing. Melanosis is an uncommon condition and is found in cats of all ages and breeds.