5 facts about blue-eyed domestic cats

Odd-eyed white Scottish Fold
Odd-eyed white Scottish Fold living in St Petersburg, Russia. Photo: Caters.
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People ask the following questions about blue-eyed cats:

  • Are blue-eyed cat deaf?
  • Are blue-eyed cats blind?
  • Are blue-eyed cats rare?
  • Are blue-eyed cats more sensitive to light?
  • Are blue-eyed cats more expensive?

These are my answers:

Blue-eyed cats are often completely white or they have large amounts of white in their fur. The two go together because of their genetic make up. Blue-eyed, white cats are not prone to hereditary blindness and they don’t go blind at an early age. They are no different to other domestic cats.

Inherited deafness (congenital deafness) is the problem with blue-eyed white cats. Research has found that, according to Cornell University College of Veterinary Medicine, 17 to 22 percent of white cats with non-blue eyes are born deaf. But the percentage rises to 40 percent if the cat has one blue eye. If an all-white cat has two blue eyes the percentage born deaf rises to 65 to 85 percent. The deafness can occur in one ear only. If a white cat has odd-eyes meaning one eye is blue and the other is say yellow and if they are deaf as well, their deafness will be on the same side of the head as the blue eye

Feral cat pictures
Odd-eyed feral cat. Photo: by stratman under a CC license.

In a study by George Strain at the School of Veterinary Medicine, Louisiana State University, the prevalence of deafness in white cats with no blue eyes was as stated above by Cornell namely 17 to 22 percent. Perhaps Cornell got the information from Mr Strain’s study or vice versa. Mr Strain’s study was a review of studies as I understand it.

If an all-white cat has two blue eyes 85 percent are born deaf in one ear (unilateral deafness) and 65 percent of born deaf in both ears. If a white cat has one blue eye 40 percent are born with unilateral deafness and 39.1 percent are born with bilateral deafness (both ears).

White Persian with clear blue eyes
White Persian with clear blue eyes. Photo: Helmi Flick.

The book: Robinson’s Genetics for Breeders and Veterinarians, states that “among a group of 240 white cats in which blue eye colour and deafness was recorded, 39 percent had blue eyes and were deaf, 29 percent were blue-eyed with normal hearing, seven percent were gold-eyed and deaf, while 25 were gold-eyed with normal hearing”.

They also confirm that all-eyed cats who were deaf, were deaf on their blue-eyed side. The white fur of an all-white cat is caused by the dominant W gene. It produces blue iris colour and deafness in 60 to 70 percent and in 40 to 50 percent of cats respectively. The authors of this book state that the deafness is gradual and is “due to degeneration of the canal of Corti” (a reference to the sensitive ‘organ of Corti’ which detects pressure impulses that travel along the auditory nerve to the brain). In essence, the hearing structures are affected by this gene causing deafness.

Blue-eyed cats are not particularly rare because all-white cats are not particularly rare either. Neither are blue-eyed cats any more expensive than other cats. The point I’m making is that the eye colour alone does not make the cat more expensive. A blue-eyed cat might be more expensive if the cat as a whole is rare and for example purebred.

Feral cat pictures
by Chriss Pagani under a CC license.

Whether blue-eyed cats are more sensitive to light is another point. I have blue eyes. There is less pigment in the iris of blue-eyed people and cats. This means that more light passes through the pigmented iris as well as the aperture i.e. the pupil. Accordingly, the eyes are more sensitive to light in my view. Certainly, for me, my eyes are more sensitive to sunlight which predisposes me to wearing sunglasses. I am taking a personal view on this from first-hand experience. But in referring to blue eyes being more sensitive to light I do not mean that the blue eyes see better in the dark. I am referring to bright sunlight causing discomfort because of light impacting the retina in a general way.

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