Congenital sensorineural deafness occurs commonly in domestic cats with a white coat. It is a congenital deafness caused by a degeneration of the inner ear. Deafness is far more common in white cats than in those with other coat colours. According to the ASPCA Complete Guide to Cats, "17 to 20 percent of white cats with nonblue eyes are deaf; 40 percent of "odd-eyed" white cats with one blue eye are deaf; and 65 to 85 percent of blue-eyed white cats are deaf."
Domesticated cats with blue eyes and white coats are often completely deaf. Deafness can occur in white cats with yellow, green or blue irises, although it is mostly likely in white cats with blue irises. In white cats with mixed-coloured eyes (odd-eyed cats), it has been found that deafness is more likely to affect the ear on the blue-eyed side. White cats can have blue, gold, green or copper coloured odd eyes.
A major gene that causes a cat to have a white coat is a dominant masking gene, an allele of KIT which suppresses pigmentation and hearing. The cat would have an underlying coat colour and pattern, but when the dominant white gene is present, that pattern will not be expressed, and the cat will be deaf. A cat that is homozygous (WW) or heterozygous (Ww) for this gene will have a white coat despite the underlying pattern/colour. A cat that lacks this dominant masking gene (ww) will exhibit a coat colour/pattern. KIT mutations have also led to patchy depigmentation and different coloured irises in humans, and KIT has been found to increase MITF expression, the gene involved in human Waardenburg syndrome type 2A.[11]
A white cat may have blue eyes for reasons other than masking. If the underlying coat pattern is one of a pointed cat (also referred to as a Siamese pattern), the blue eyes may come from the genetics of the pointed gene.
A common misconception is that all white cats with blue eyes are deaf. It is possible to have a cat with a naturally white coat without this gene, as an extreme form of white spotting, although this is rare – some small non-white patch usually remains.
There is no reason your deaf cat shouldn't have a happy, fun-filled life. Some pets are born deaf or are genetically predisposed to deafness. For example, blue-eyed white cats can be born with a condition that results in deafness. At other times, illness or injury may lead to hearing loss. With a few accommodations, deaf cats shouldn't have any trouble in most households.
Before You Begin
It's important to understand cat hearing when living with a deaf cat. Normal cats hear much better than we do and youthful pets generally hear better than middle-aged and older animals. Cats more or less hear the same low-pitched sounds as humans, but they are far better at higher frequencies. At typical volumes, cats can hear up to around 79 kHz.1 People can only hear sound waves up to 20 kHz. Your cat can hear sounds in a 10.5-octave range, a wider span of frequencies than almost any other mammal. That allows your cat to easily hear extremely high-pitched sounds like rodent squeaks.
With age, the delicate structures of the inner ear begin to lose their sensitivity to vibration. This normal age-related hearing loss, called presbycusis, develops in every pet that lives long enough, just as it does in aging people. Hearing loss can be accelerated by damage from loud noises. Chronic ear infections and other illnesses or injuries may also result in hearing loss.
Cats can’t tell us that they’re hard of hearing, and they compensate well by paying more attention with their other senses. They may meow loudly (because they can't hear themselves), watch owners and other pets more closely, and cue off of their behavior to know that somebody’s at the door, for example.3 Deaf pets may also pay closer attention to vibration and air currents. The breeze made by an open door may cue them you’ve come home from work. Even when they can’t hear the can opener, the cat’s internal “clock” will announce suppertime. All of this means that you may not notice hearing loss in your cat until it is quite profound.
What You Need
If you suspect hearing loss, speak with your veterinarian.2 The doctor can determine whether a medical problem is to blame and recommend appropriate treatment. To do some deafness tests at home, gather some household items like:
- Paper
- Keys
- Tinfoil
- Cardboard box
Make some noises outside of your cat's line of sight like tearing paper, jingling keys, crunching foil, or tapping on a cardboard box. Use various sounds to test high and low frequencies. If your cat ignores some or all of the noises, there is likely hearing loss. A specialty veterinary center can confirm with a Brainstem Auditory Evoked Response (BAER) procedure.
Communication
It is still possible to communicate with a deaf pet. Use visual or tactile signals rather than your voice. Cats easily learn to respond to hand signals, the beam of a laser pointer, or a light flicked on and off to come for dinner. Deaf pets startle more easily.4 Always approach your pet so he sees you coming, and stomp your foot or give him some other warning before petting him to avoid being accidentally nipped or scratched when you startle him.
Focus on Vibrations
A “dog whistle” that uses high-frequency sound waves may still be detectable to your hearing-impaired pet even when it can no longer hear your voice. Low frequency vibrations may be felt, even when your pet can’t hear. A vibrating collar is also be a great way to get your cat's attention. Use that as a signal to call your pet and as a training device.
A “pet locator” may be helpful when your cat can’t hear you, and you can’t find it. Attach a pendant to the cat’s collar that emits a light tone when the transmitter is activated. A “key finder” product should work well for this purpose.
Keep Them Indoors
There are far too many threats outdoor for deaf cats.2 They can't hear barking dogs, honking car horns, or people yelling, "Watch out!" Provide your cat with a comfortable seating area next to a window where they can look outside and see all that's going on.
Deaf cats are still happy pets. Some hearing loss is a normal part of the aging process for both cats and humans. Making simple accommodations for a hearing-impaired pet isn’t difficult. Besides, it’s what we do for all our friends and family, and our cats are no exception.
Prevention
Depending on the cause of the deafness, it may not be preventable. Some hearing loss due to aging is natural and cannot be stopped. Treat bacterial infections, ear mites, or other health problems quickly and with the assistance of your vet. Left untreated, some of these health conditions can result in permanent hearing loss.