Deaf White Cat Syndrome

It's PAWS-itively Genetic!

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History

  • 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
Living with a Deaf Cat

Genetic Transmission

  • 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.

Phenotypes

Genotypes

  • 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?

Deaf cats make up for their handicap by having greater tactile sensitivity, greater visual capacity, and an acute sense of smell. They behave no different than a hearing cat, and can live long and happy lives without their defect negatively affecting them. So why is deafness a problem? Large amounts of deaf white kittens get put down because of their liabilities and the training challenges they present to their owners. Deaf cats are also at a higher risk from undetected dangers, such as motor vehicles or predators, thus they require a protective indoor lifestyle.
Mimo the white deaf cat is hard to wake up!

Known Carriers

Pure cat breeds carrying the white (W) coat pigment gene and are at risk for congenital deafness include:



  • White
  • White Scottish Fold
  • European White
  • Foreign White
  • Norwegian Forest Cats
  • Ragdoll
  • Siberian
  • 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

Eradication Methods

Only current eradication method is to identify the animals affected by the hereditary forms of deafness (both unilaterally and bilaterally) through hearing testing, and to remove them from the potential breeding pool to prevent future deaf animals.

Opinion

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?

References

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.

doi:10.1016/S0378-5955(97)00182-2

http://www.sciencedirect.com.ezproxy.proxy.library.oregonstate.edu/science/article/pii/S0378595597001822


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.

doi:10.1016/S0378-5955(97)00114-7

http://www.sciencedirect.com.ezproxy.proxy.library.oregonstate.edu/science/article/pii/S0378595597001147?np=y


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.

doi:10.1016/0006-8993(96)00719-6

http://www.sciencedirect.com.ezproxy.proxy.library.oregonstate.edu/science/article/pii/0006899396007196


Strain, G. (2007). Deafness in blue-eyed white cats: The uphill road to solving polygenic disorders. The Veterinary Journal. 173. P471-472.

http://www.lsu.edu/deafness/VetJEd2007WhiteCat.pdf


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