One blue eye and one yellow eye in a cat: What causes it?

Cat with one blue eye and one yellow eye is usually determined by genetics, and occasionally caused by acquired lesions. This condition is generally referred to as "heterochromia" or "split-colored eyes". If caused by genetics, this abnormality will not affect the cat's vision but may impact its hearing. Cats with such eyes may experience hearing loss in one or both ears in their later years. If the condition is caused by acquired lesions, it is recommended for the owner to take the cat to a pet hospital for inspection, and then proceed with treatment after confirmation.

Genetic Determination

Heterochromia caused by genetic factors is mainly caused by white or cream genes. If the cream gene invades the position controlling the eye pigment gene, it will form blue eyes, and if it doesn't invade the other eye, it will be yellow. Heterochromia is common in Persians and white-haired cats. Although this abnormality doesn't affect the cat's health and hearing, cats with heterochromia usually have hearing difficulties.

Acquired Lesions

If a cat's eyes were previously the same color, the difference in color may be due to acquired factors such as illness or injury that affect the generation of iris pigment cells, thereby changing the original color of the eyes. If this is the case, it is best for the pet owner to take the cat to a pet hospital promptly for inspection to determine the specific cause and then carry out targeted treatment.

Note: Approximately 75% of cats with heterochromia have hearing loss in the blue-eyed side, but cats with blue eyes caused by chinchilla gene, such as goldens and silvers, have normal hearing.