Deafness in animals often goes undetected because so few people are on the look-out for it. Cat-breeders, however - more specifically, breeders of British short- and long-haired whites - are only too familiar with the condition.
The gene that makes a cat white all over has other effects besides determining the colour of its coat. It is also responsible, in combination with other genes, for the colour of a cat's eyes and for the formation of its ears. Many white cats are born with a congenital hearing defect - sometimes just in one ear, sometimes in both. The eye-colour of white cats is also unpredictable; some have orange eyes, some blue, a few even have odd-coloured eyes, one orange and on blue.
Unfortunately the cats most frequently found to be deaf are those with blue eyes, the variety that appeals most to the tastes of buyers. However, a created breed, the blue-eyed Foreign White, which has added Siamese blood, is able to hear perfectly well.