Surely you’ve ever heard that white and blue-eyed cats are deaf. This is not always the case: not all white cats are deaf. The probability of being deaf is based on the color genetics of the cat.
The genetics of color in cats
There are many genetic characters that depend on the cumulative action of several genes, from the interaction with other genes or even from the environment. The color in felines is an example of this type of character.
There are many varieties in the color of cats, the result of crossing between cats with different layers of color. In a single individual, the color can be determined by the action of several genes and, depending on the inheritance they have received, have different dominance between their alleles.
An allele is a version of a gene, so that for the same gene we can have an allele that can be dominant or recessive. According to the alleles that combine to form the fur, the adult cat will have a certain color.
The white cats and the white gene
He white gene In cats it is responsible for depigmentation: it is related to the lack of cells that produce color, the melanoblasts from which the melanocytes develop. The white color is the lack of pigmentation and is due to the absence of melanin, the substance produced by melanocytes.
W alleles of white gene They explain the white spots on the cat. There are four alleles for this gene that define four different phenotypes and have the following dominance relationship: (WT> Wh> Wl> w +).
- Total depigmentation. Given by the WT allele, which predominates over the other alleles and masks the staining that others contribute, this is called the epistatic effect. It is also associated with blue or green eyes, one or both; these types of cats are the most likely to suffer from deafness.
- Stained. These cats may have spotted areas of other colors, such as orange.
- Partial spotting.
- Solid layer. These cats are recessive for the w + w + allele; They are non-white cats.
Albinism in cats occurs by a different gene. Each color layer in cats is determined by different genes and the interaction between them.
Why does white color relate to deafness?
As you know, melanocytes have a direct role in the expression of color in animals, both fur, and skin and eyes. But they are also related to the formation of the auditory system during embryonic development.
The expression of W causes that during the embryonic development the cells that form the melanocytes do not reach different parts of the cat’s body and produce color. For this reason, white spots, blue eyes or total depigmentation occur. If the melanoblasts do not migrate to what will be the future ear of the cat, it does not fully develop and can lead to a deaf cat.
Not all white cats are deaf: it depends on their genetic inheritance, specifically the shape of the white gene that they have received from their parents.
Some white cats are deaf: how to know?
It can be difficult to know just by observing the animal, since it can compensate for your deafness with the rest of your senses. Cats have a highly developed sense of smell, good night vision and ability to detect movement thanks to their whiskers, so to confirm deafness we need to go to the vet to perform a specific test.
This test is called the BAER test (Brainstem Audirtory Evoke Response) and records the electrical activity in the cochlea and the auditory pathways in the brain before the execution of a sound.
Caring for a deaf cat is not so different from that of a cat with hearing ability. However, you can take care of some details to make your life easier. Read more “