White cat with blue eyes
Some white cats suffer from congenital deafness caused by degeneration of the inner ear. This condition is associated with blue irises. In white cats with mixed-coloured eyes (odd-eyed cats), it has been found that deafness is usually limited to the ear on the blue-eyed side. White cats can have blue, gold, green, or copper coloured odd eyes. In one study of white cats with varying degrees of hearing deficiency, 72% of the animals were found to be totally deaf.