Researchers found that only 17 to 22 percent of white cats with non-blue eyes are born deaf. The percentage rises to 40 percent if the cat has one blue eye, while upwards of 65 to 85 percent of all-white cats with both eyes blue are deaf. Some of these cats are deaf in only one ear.
What is the risk of deafness in a white cat?
The following figure illustrates the relationship between coat and eye color and the risk of deafness. If deafness occurs, it may be either unilateral or bilateral.
Deaf cats with white coats and either one or both blue eyes comprise approximately 1-1 of all cats. 5% of the total cat population. Nonetheless, there are regional differences in the frequency of white cats.
A white cat is three to five times more likely to be deaf if it has two blue eyes than if it has two non-blue eyes. A cat that has one blue eye is roughly twice as likely to be deaf as a cat that has two non-blue eyes. Additionally, the likelihood of bilateral deafness in longhaired white cats is three times higher. Deaf white cats face significant negative pressure from natural selection when living in the wild, as follows:
- They are deaf
- Because of their blue eyes, they are photophobic, or intolerant of bright light.
- They have reduced vision in low light conditions
But white cats are far more common in pet cats, most likely just as a result of selective breeding (human preference and intervention). Numerous cat breeds are known to carry the gene for white coats, which means they can result in deaf white people. Nowadays, a number of breeds mandate that white cats undergo hearing tests (e g. utilizing brainstem auditory evoked response testing, or BAER testing—a straightforward, non-invasive test that can be carried out at specialized facilities to precisely ascertain whether deafness is present. It is not permitted to breed deaf white cats from these breeds.
How Do Genes Play a Role?
Just as genes shape who we are, they also shape who animals are. Similar to how our genes can affect our hair color or level of athleticism, a cat’s genes can determine its appearance and potentially innate traits like deafness. It turns out that there is a strong genetic correlation between deafness in cats and the genes that produce a white coat and blue eyes.
The link between deafness and cats with white fur and blue eyes has long captivated geneticists and cat breeders. Researchers have discovered that the snow-white coat coloration is caused by a single dominant gene known as W (for White). Additionally, this gene causes deafness and blue eyes.
A cat will have a white coat with 100% certainty if it carries the W gene. But if the cat has the W gene, there’s also a chance that it will be equally likely to have blue eyes and deafness. The gene is highly associated with both eye color and intrinsic deafness because there is an equal chance of developing these two characteristics. Not all blue-eyed, white-coated cats are deaf, though the great majority are. Researchers think that the W gene, which also causes deafness in cats, may be influenced by other recessive genes and environmental factors.
Is There a Test for Deafness in Cats?
White cats are very sought-after, and some breeders will only work with cats that have white fur. Breeders must frequently test new kittens for deafness due to the high prevalence of deafness in white-furred cats in order to properly manage and care for their cats. Fortunately, a quick and safe test exists to determine whether a cat is deaf.
An easy test that a veterinarian can administer is the BAER test. A specialist can administer the brainstem auditory evoked response test, which looks for an instant reaction in cats. The test takes five to fifteen minutes to complete, and most cats can take it without being sedated. The test looks for a hearing response in addition to examining the ear’s structure to detect the presence of deafness.
FAQ
What breed of cat is prone to deafness?
Why do white cats usually have blue eyes?
Are cats with blue eyes rare?
Are all heterochromia cats deaf?