Deafness and Hearing Loss in Cats
Some cats are born without the ability to hear because of developmental defects in the hearing apparatus. Cats may also be deaf in just one ear. Congenital deafness occurs most often in white cats with blue eyes, and is the result of an incomplete autosomal dominant gene. However, not all cats with blue eyes are deaf, and that includes not all white cats with blue eyes. Longhaired cats with blue eyes have a higher risk of deafness than shorthaired cats with blue eyes. White cats with the Siamese dilution gene may have blue eyes with no hearing impairment. Still, white cats have a higher risk of deafness than other cats in general, and blue-eyed cats also have a higher risk of deafness-even if they have only one blue eye. Congenitally deaf cats should not be bred.
Common Breeds with the White Coat Pigment Gene
Gradual Hearing Loss
Loss of hearing can be caused by old age, middle ear infections, head injury, blockage of the ear canal by wax and debris, and by certain drugs and poisons. In particular, the antibiotics streptomycin, gentamicin, neomycin, and kanamycin, if used for long periods, can damage the auditory nerves, leading to deafness and signs of labyrinthitis.
Gradual loss of hearing occurs in some older cats. Elderly deaf cats, however, often retain their ability to hear high-pitched sounds beyond the range of human hearing.
It is difficult to tell if a cat is going deaf. The ability to hear must be judged by observing the cat's actions and how she uses her ears. Cats who hear well cock their heads and look toward a sound. The ears swivel to pinpoint the source of the sound. Accordingly, lack of attentiveness is one of the first indications that a cat is not hearing well. One way to test this is to make a loud noise while the cat is asleep. If the cat does not startle and wake up, you can assume there is a significant loss of hearing. Suddenly touching a sleeping deaf cat without a warning could result in a scratch or a bite as the cat is startled when she wakes up. Stamping on the floor will attract a deaf cat's attention, because she can feel the vibrations.
Deaf cats get along quite well. They use their senses of sight and smell and the tactile sensations transmitted through their whiskers to compensate for the hearing loss. However, deaf cats should not be allowed outside.
This article is excerpted from “Cat Owner's Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
Copyright © 2008 by Delbert Carlson, DVM, and James M. Giffin, MD. All rights reserved.