Deafness can be present at birth (congenital) or develop later from infection, trauma, toxins (including certain drugs), or changes due to aging.
Congenital deafness can be inherited or caused by damage before birth from a poisonous substance or a virus. Sometimes, but not always, cats with white fur and blue eyes are deaf. In these cases, changes in the first week of life cause hearing loss.
Vets diagnose congenital deafness by careful observation of a cat’s response to sound. In groups, a deaf cat can copy others and go unnoticed. Testing is more reliable after cats are 3–4 weeks old, when sound responses become predictable. Cats deaf in only one ear are especially hard to diagnose without specialized testing.
Acquired deafness develops later and can result from blockage of the external ear canal due to chronic outer ear infection, middle or inner ear infections, excess earwax, or damage to the tiny ear bones. Inflammatory polyps (growths) can also cause deafness. As with people, cats can have partial hearing loss or one-sided deafness. Removing blockages or healing damaged tissue often restores hearing.
Some causes create permanent damage. These include inner ear trauma, middle or inner ear infections, loud noises, diseases, drugs (like certain antibiotics or aspirin), anesthesia, aging, and tumors.
Cats with bacterial ear infections may regain hearing after taking antibiotics. Recovery from other causes varies. There is no treatment for congenital deafness. Many deaf or partially deaf cats adapt well, but for safety they should only go outdoors on a leash.
Also see professional content regarding deafness.
