It is often said that white cats are more likely than others to be deaf. This is a scientifically proven fact. However, the risk is more or less important depending on the color of their eyes, since deafness is a genetic defect linked to the color of the hair and eyes. Find out the reasons for this amazing phenomenon.
The deafness of the white cat: genetics at fault
A white-haired cat is more likely to be deaf than another. This peculiarity is explained by genetics, and more particularly by a genetic mutation. The W gene is involved, because it is what prevents the cells responsible for pigmentation from activating and functioning normally; as a result, the cat's coat does not color and remains white. However, it turns out that the W gene (for White gene) can, when active, cause the destruction of the cells of the organ of Corti, at the level of the inner ear, which causes deafness of the animal. This manifests itself from the first days after the kitten is born. This genetic anomaly is comparable to Waardenburg syndrome in humans. In this case also, the persons concerned have a dysfunction of the organ of Corti associated with an absence of skin pigmentation.
In addition, deafness is more or less frequent depending on the color of the cat's eyes. It is estimated that when a white cat has blue eyes, it has a 50% risk of being deaf. If he has minnow eyes, that is, a blue eye and a green or brown eye, he is 40% likely to be deaf. On the other hand, if none of his eyes is blue, the risk of deafness drops to 20%. Conversely, if all kittens are born with blue eyes, as in humans, it is estimated that 70% of cats with the W gene will keep this blue color as they grow.
Deafness in white-haired cats is therefore not systematic, as some have perfect hearing, and it is not always bilateral. Some cats with snow-colored coats are only deaf in one ear. And strangely enough, when these cats have minnow eyes, it is often the ear on the side of the blue eye that is deaf. Similarly, cats that do not have an entirely white coat, that is to say if it contains spots of another color, the animal does not have the W gene and therefore has very little risk of being deaf. However, some white cats are born with a patch of another color on the head; it is the color that the animal would have worn without the W gene. But in this case, this small spot disappears with age.
Finally, do not confuse white cats and albino cats. In the case of the latter, another genetic mutation is at work and these animals are not more deaf than normal.
Deafness in cats: a heritage to live with
Why are some cats deaf and others not? This question is complex and involves many genetic factors, beyond just the color of the fur and the eyes. In this case, it is said that this explanation is polygenic, that is to say that it is the consequence of several genes whose sum generates deafness and most of which are not yet identified by science.
When a white cat is born deaf, we cannot expect an improvement in its hearing with age. Conversely, if a white cat is not born deaf, but becomes so as it ages, this hearing loss will not be linked to the W gene, but to a normal degeneration of hearing due to age or illness.
It seems that deaf cats compensate for part of their hearing loss with better vision. Indeed, studies have shown that deaf tomcats are able to better understand movement, in particular the speed of movement of an object, and they seem to have a wider field of vision than a hearing cat.
Unfortunately, deafness in white cats is not without consequences. They are much more sensitive animals and more prone to stress. Indeed, the loss of hearing generates a loss of reference points that the other senses are not able to completely compensate for. These cats are therefore much more sensitive in the event of changes, they are often more distant, sometimes even more aggressive. They are also generally more talkative and louder, as they try to be heard, but without measuring the range of their voices.
Owners of deaf white cats are advised to avoid or greatly limit access to the outdoors, as the pet does not always perceive the danger. Indeed, the risk of being struck by a vehicle is increased because the animal does not hear it coming.
To reduce the risk of giving birth to a deaf kitten during breeding, certain crosses should simply be avoided.
Avoid crossing two white cats. At least one of the two parents must be colored, but be aware that the white mask will remain dominant on the litter if one of the parents is white. On average, only 25% of kittens born to a white parent and a parent with colored fur will be born deaf, while the risk rises to 50% with two white parents.
Avoid breeding a cat that is already deaf. In this case, the risk of transmission within reach is around 50%.
Avoid crossing two blue-eyed cats, even if they are not white, as the risk of deafness remains, although it is difficult to quantify.