Wednesday, December 17, 2008

White Cats

White CatsWhite cats, like all white animals in general, are both valuable – and vulnerable. The white of their coat is not a real colour but rather the absence of colour, which also means absence of protection from the sun’s harmful ultraviolet rays. It is the variety and distribution of natural “dyes” in an animal’s skin and fur that explain different coat colours and patterns. One of these dyes is melanin, the chief protector of skin against ultraviolet radiation. The skin of white cats has either no melanin at all or very little of it, which is why they are far more vulnerable to sunburn and cancer of the skin than coloured cats. The “classical” wild-type cat is a brown tabby, which combines optimal protection from the sun with a camouflage pattern that hides it from predators. When we consider that cats evolved as desert animals that spend much of their time under the blazing sun, it is fascinating that white cats exist at all. They are clearly an example of how centuries of breeding have produced animals that are both stunningly beautiful and dependent on humans for their continued survival and protection.

Such protection involves, first and foremost, keeping a white cat out of the sun or limiting its exposure to the sun. The best way to do this is to raise a white kitten strictly indoors so that it is not tempted to go outside as an adult. Spaying or neutering the cat is part and parcel of an indoor lifestyle since intact animals are driven to go outside in search of a partner, and torment themselves and their owners when confined indoors. However, if a white cat has been adopted as an adult and is already used to spending time outdoors, chances are that it will be miserable and restless if not allowed to do so, especially in the short term. If the cat is happy to simply be outdoors and does not insist on roaming, it can be tethered to a tree or post in a shaded area and supervised as it watches birds and chills out. For cats that are used to coming and going, applying sun-block cream to the ear rims as well as the nose, eyelids and lips can go a long way toward protection, if the owner is able to do this and the cat does not protest. If possible, the cat’s outdoor time should be restricted to late afternoon and evening hours, avoiding the morning and early afternoon when the sun is at its harshest.

Another method tried by some owners is tattooing ear rims, the area most likely to develop sunburn and skin cancer. A veterinarian may inject artificial dye in place of the protective melanin which white cats lack. This method has at least two drawbacks. First, the dye is injected in spots and does not spread evenly, with the skin between the spots remaining unprotected. Secondly, the dye ends up under the surface layer of the skin, the layer most susceptible to sunburn and cancer, which is thereby left unprotected.

In the absence of protection, and often in spite of it, white cats exposed to the sun will almost certainly develop sunburns which, with repeated exposure, will likely become cancerous. Signs to look for are reddened bumps on the ear rims or around the nose, eyes and lips. Unlike insect bites or allergic reactions, these bumps are seldom if at all itchy. The sooner such a cat is treated by a veterinarian, the better the chances of controlling the skin cancer, since this form of skin cancer often responds well to treatment. This is, of course, only a temporary solution if the cat remains exposed to the sun.

Not all white cats are created equal. Many come in “shades” of white. While most of their coat is indeed white, the fur on the tips of their ears and around the face and feet can be a pale cream or orange. This would be an extreme case of a point pattern, with Siamese and Himalayan cats representing the classical pattern. Interestingly, the darker colour at the tips of the ears, nose and feet in these cats develops because of lower body temperature over those areas. Such “off-white” cats can sometimes develop dark spots on their lips or nose, especially at a young age. This is very common among orange cats, and is normal as long as these spots are flat and the skin is otherwise unchanged. Other cats can be a very light, silvery gray with darker fur around their eyes; this is common in Persian cats.

Cats with a pure snow-white coat are a varied population based on their eye colour. For instance, a white cat with blue eyes is missing surface “dye” in its eyes as well as its coat: blue eyes in an adult cat mean lack of colour in the upper layers of the iris. What appears blue is really black, the result of the melanin (black dye) in the deeper layer of the iris without overlay of other colours in the top layers. Such cats are also usually deaf, since the gene responsible for iris colour goes hand in hand with the gene responsible for hearing. Deaf cats need extra care for obvious reasons: outside of their home, they are vulnerable to approaching dangers such as cars or aggressive dogs or other predators. If they go outside, they must be walked on a leash or tethered and kept under very close supervision. In addition, deaf cats make poor mothers since they cannot hear the mewing of their kittens.

The kittens of two white blue-eyed cats do not always resemble their parents: some can have coloured fur as well as coloured eyes. Likewise, two coloured cats whose ancestors included white cats can have white kittens among their offspring. These seemingly unexpected results are due to the way genes come together to make a new generation of animals. Your veterinarian or an experienced and reputable breeder will be able to give you an idea of what colours of kittens to expect from two cats whose ancestry is known.

Many white cats have a blue and a green eye. Unlike blue, green means presence of colour; hence these cats are deaf in only one ear – but it is not necessarily on the same side as the blue eye. Other white cats have orange eyes, which is also due to a colour in the upper layers of the eye, above the black melanin. Albinos, or animals with complete lack of colour or melanin in their skin, fur or eyes (their eyes appear red because you can see through the completely colourless outer layers to the blood vessels in the iris), are exceedingly rare among cats. Thus white cats, when properly cared for, combine the beauty of a snow-white coat with variation in eye colour which means protection of the eye.
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3 comments:

Rosa Blenn said...

I have a pure white cat with two green eyes - is she valuable? Thanks.

Unknown said...

Ihave a white cat green eyes this is the second time he gets sunburn he has brown spots now around the nose area I have use antibiotic cream and aloe vera gel he liks it all

Anonymous said...

i have 3 pure white cats. 2 female 1 male. mine have like bright yellow eyes though. i can't keep my one female indoors hardly ever, i got her as a stray.

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