The White Norwegian Cats
Cats can also lose their hearing due to age, like humans do. In this case it is generally a gradual process that is sometimes difficult to notice. The eardrums become less flexible and the sound is not transmitted effectively. Other cats, on the other hand, are born partially or completely deaf due to a genetic defect. In many cases this genetic defect is related to the pigment or is found much more often in totally white cats.
In fact, completely white cats with blue eyes are well known to be very often affected by a congenital hereditary deafness that can involve one or both ears.
Breed studies have therefore defined the relationship between deafness and white cats with blue eyes.
The responsible gene is a dominant gene which is defined W (White). The first studies on this gene date back to 1930 and have been deepened in the following years. The W gene is a pigment-related gene in cats and is a dominant color gene, but it is not linked to albinism. Cats carrying this gene are not always solid white in color, but they often have colored patches on their heads which may disappear with age.
In fact, we often see a young kitten with a colored speck, generally on the head, which then disappears in adulthood. The color that is hidden under the white cloak, dominated by W, is revealed by that speck!
Because of this, white cats can produce non-white or two-tone kittens.
This gene has complete penetration for white coats, in fact all cats that have this gene also have white coats, but it has incomplete penetration with regard to the blue color of the eyes, related to deafness, even if they are closely related.
However, not all white cats are deaf and not all blue-eyed cats have a deafness defect.
The penetration variable of deafness linked to the blue color of the eyes can be caused by the interaction with other genes or with environmental factors.
Furthermore, if we are in the presence of deafness, this can refer to both eyes or even to only one eye, so it can be bilateral or_cc781905-5cde-3194badd_ .
How do we know that the cat is deaf?
These cats generally show some changes in behavior. We can notice it since, even calling them, they do not approach or do not notice when we return home.
If the deaf cat lives with another cat, we will generally notice that it tends to refer to him for hearing. This means that we will often find him observing the other cat, to understand what is happening. If, on the other hand, it is a single cat in the house with the problem of deafness, it is much easier to notice this defect. The cat, for example, may sleep very soundly, may not notice when we enter the room and may not be aware of very loud noises even close to it. If there is no reaction to a very loud clap or noise, we can really suspect possible deafness.
White cats or albino cats?
However, it must be specified that these cats are not albini.
A true albino cat not only has a white coat, but also the eyes have no pigment, they appear pink. An albino cat is very sensitive to light and needs sunscreen on their ears to prevent skin cancer. However, this prevention is necessary for all white cats.
White cats with blue, orange and green colored eyes are not albinos. Albinism is a very different mutation that causes color absence, not color coverage.
In the presence of the W gene, white coat and blue eyes, we can have the absence of the glossy carpet (it also happens in some cats with blue eyes with diluted white coat - Siamese) or a very thin glossy carpet, which means that the visibility at night it is very small. This is one more reason not to allow the deaf white cat to go out!
Studies have shown that if:
◊ Un white cat has both blue eyes is 3-5 times more likely to develop deafness than a cat with non-blue eyes.
◊ A white cat with only one blue eye has about twice the opportunity to be deaf than a cat with both eyes of a different color.
◊ White long-haired cats are three times more likely to be bilaterally deaf.
What are the problems encountered?
Deaf cats emit very strong vocals just because they don't hear exactly like humans. Due to the extreme utility of hearing in predation and the ability to hunt, this can be reduced in completely deaf or partially deaf cats. Complete deafness, in any case, does not supersede success in hunting. A deaf cat responds equally to its predatory instinct.
This is why vocalization in completely deaf cats is an important means of communication between cats, and deaf cats may be less good at communicating with their peers. Deaf cats can conflict with other cats much more often or fail to integrate well into a group. They may find it more difficult when they are still puppies and, moreover, they are more frequently rejected by their mother. Their reduced ability to recognize dangers is the most serious handicap especially when it comes to cats that live outside. Cars, dogs, garden machinery, are the biggest dangers.