Deaf White Cat Syndrome
It's PAWS-itively Genetic!
- DWCs (Deaf White Cats) with blue eyes first reported in 1828
- Cats of this type were first bred in 1918 by Whiting, who concluded that the defect was a dominant autosomal aberration that was distinctly different from albinism
- Many publications suggest that DWCs are the feline homologue of the human Waardenburg syndrome = hearing loss, change in pigmentation of the hair, skin, eyes; commonly have pale blue eyes, distinctive hair coloring (such as having a patch of white hair, or hair that prematurely turns gray)
What does it look like?
- White fur (deafness suggested to be more common in long-haired)
- Not always solid white - often have colored spots on their heads that may fade or disappear with age
- Predominantly blue-eyed (either both or one eye), can also have no blue eyes, but much rarer
- Congenital deafness develops by 2-4 weeks of age, hearing test conducted starting at 5 weeks to test for unilateral or bilateral deafness
- Caused by degeneration of cochlear hair cells
- Thought to be caused by white (W) pigment gene, or possibly the recessive piebald gene (S)
- The white (W) pigment gene is autosomal dominant over color (w), but is unrelated to albinism
- Not sex-linked
- No certain mechanism for inheritance is known - most likely a polygenic disorder
- Suggested that purebred white cats are less often deaf than mixed-breed white cats
- Deafness increases with the number of blue eyes
- Deafness in cats may not always be the result of the same genetic defects
- When white gene is strongly expressed, it represses melanocytes (which produce pigment granules) not only in the skin but in the eyes (blue eyes are a result of missing pigment granules, the same reason the sky is blue)
- Melanocytes originate embryonically in the neural crest, along with other neural cells
- Melanocytes in stria vascularis (cochlear duct) necessary for maintaining ionic environment needed for cochlear hair cells
- Repressing stria melanocytes causes the stria to degenerate; the hair cells die and various cochlear structures collapse and auditory nerve fibers start to degenerate
Not all blue-eyed, white animals are deaf, there's just a strong correlation.
Deafness is most likely to affect the ear on the side of the blue eye (unilateral deafness); with one blue eye, cat is 2x more likely to be deaf than cats without one blue eye
Congenital deafness can also be found (less commonly) in cats with green, gold, or copper-colored eyes.
Most commonly associated with deafness
Can be unilateral (one ear) or bilateral (both ears); with two blue eyes, deafness 3-5 times more common than cats without two blue eyes
White with Long Hair
suggested that white cats with long hair have a higher prevalence of blue eyes and deafness than short-haired cats
White with Short Hair
lower prevalence of deafness than long-haired cats
- Studies found it difficult to cite single prevalence rate
- In two different studies, prevalence rates among white kittens for deafness in one or both ears were 51.5% and 42.6%, respectively
- Kittens that were homozygous WW were found to yield a prevalence that ranged 52-96% deafness; heterozygotes were 24.3% and 27.4%
- One study used at least one bilaterally deaf parent, while the other included all possible hearing populations in the parents, making it difficult to compare results
Why Is It A Problem?
- White Scottish Fold
- European White
- Foreign White
- Norwegian Forest Cats
- White Turkish Angora
- White American Wirehair
- White Cornish Rex
- White American Shorthair
- White Devon Rex
- White British Shorthair
- White Manx
- White Exotic Shorthair
- White Persian
- White Oriental Shorthair
- White Maine Coon
People should make every effort to make sure their cat is spayed or neutered, especially if the cat is white and proven to be deaf in one or both ears. While deafness is certainly not a death sentence for most cats, it’s a fact that these cats are less desirable for most people, and more likely to be put down because of it. And not all cats are lucky enough to be given a safe, indoor home—cats that have to survive outdoors are at a much greater risk for injury or death when they are unable to hear. Do you think it should be required for owners of deaf cats to fix their animals, or do you feel that the disorder is merely a quirk that is easy to work around?
Heid, S., Hartmann, R., & Klinke, R. (1998). A model for prelingual deafness, the congenitally deaf white cat – population statistics and degenerative changes. Hearing Research. 115 (1-2). P101-112.
Hartmann, R., Klinke, R., & Shepherd R.S. (1997). Response of the primary auditory cortex to electrical stimulation of the auditory nerve in the congenitally deaf white cat. Hearing Research. 112 (1-2) P115-133.
Saada, A., Niparkoa, J., & Ryugoa D. (1996). Morphological changes in the cochlear nucleus of congenitally deaf white cats. Brain Research. 736 (1-2). P315-328.
Strain, G. (2007). Deafness in blue-eyed white cats: The uphill road to solving polygenic disorders. The Veterinary Journal. 173. P471-472.
Strain, G. (2003). Hereditary Deafness in Dogs and Cats: Causes, Prevalence, and Current Research. Tufts' Canine & Feline Breeding and Genetics Conference. Web. Accessed 27 April 2016. http://www.lsu.edu/deafness/Tufts.htm
Strain, G. (2007). Cat breeds with Congenital Deafness. Louisiana State University School of Veterinary Medicine. Web. Accessed 28 April 2016. http://www.lsu.edu/deafness/catbreeds.htm