Title: Congenital sensorineural deafness in cats

{{Short description|High rates of congenital deafness in white cats}}
[[File:A completely deaf, pure white blue-eyed cat.jpg|thumb|A completely deaf, solid white, blue-eyed cat]]
[[File:Deaf White Cat.jpg|thumb|A deaf white cat with yellow eyes]]
{{Use British English|date=September 2023}}
{{Use DMY dates|date=September 2023}}
[[File:Deaf White Cat.png|thumb|This engraving depicts two cats on a wall with a dog barking below them. The spotted cat hisses at the dog while the deaf white cat dozes, unaware of the barking.]]
'''Congenital sensorineural deafness''' occurs commonly in domestic [[cat]]s with a white coat. It is a [[congenital deafness]] caused by a degeneration of the [[inner ear]].&lt;ref name=&quot;Bosher&quot;&gt;{{cite journal|last1=Bosher|first1=SK|last2=Hallpike|first2=CS|title=Observations on the histological features, development and pathogenesis of the inner ear degeneration of the deaf white cat|journal=Proceedings of the Royal Society B: Biological Sciences|date=13 April 1965|volume=162|issue=987|pages=147–170|doi=10.1098/rspb.1965.0030|pmid=14285813|bibcode=1965RSPSB.162..147B|s2cid=36675534}}&lt;/ref&gt; Deafness is far more common in white cats than in those with other coat colours.

== Occurrence ==
Domesticated cats with blue eyes and white coats are often completely deaf.&lt;ref name=&quot;pmid208085813&quot;&gt;{{cite journal |last1=Webb |first1=A. A. |last2=Cullen |first2=C. L. |date=June 2010|title=Coat color and coat color pattern-related neurologic and neuro-ophthalmic diseases|journal=Can. Vet. J.|volume=51|issue=6|pages=653–7|pmc=2871368|pmid=20808581}}&lt;/ref&gt; [[Charles Darwin]] mentions this phenomenon in his book, ''[[On the Origin of Species]]'', to explain correlated variation.&lt;ref&gt;{{cite book |first=Charles |last=Darwin |author-link=Charles Darwin |url=https://books.google.com/books?id=YY4EAAAAYAAJ |title=On the Origins of Species |date=1909 |orig-year=1859 |isbn=9788187572664 |page=13 |publisher=P. F. Collier }}&lt;/ref&gt; Deafness can occur in white cats with yellow, green or blue irises, although it is mostly likely in white cats with blue irises.&lt;ref&gt;{{cite web|url=https://www.vet.cornell.edu/fhc/health_information/deaf.cfm|title=Ask Elizabeth: White Cats and Blindness/Deafness|website=Cornell University College of Veterinary Medicine|publisher=Cornell University College of Veterinary Medicine Ithaca, New York|access-date=3 December 2016}}&lt;/ref&gt; In white cats with one blue eye and one eye of a different color ([[odd-eyed cats]]), deafness is more likely to affect the ear on the blue-eyed side.&lt;ref name=&quot;Bosher&quot; /&gt; Approximately 50% of white cats have one or two blue eyes.&lt;ref&gt;{{cite journal |last1=Bergsma |first1=D.R. |last2=Brown |first2=K.S. |title=White fur, blue eyes, and deafness in the domestic cat |journal=Journal of Heredity |date=May 1971 |volume=62 |issue=3 |pages=171–183 |doi=10.1093/jhered/62.3.171 |pmid=5137350 }}&lt;/ref&gt;

According to the [[ASPCA]] Complete Guide to Cats, &quot;17 to 20 percent of white cats with non-blue eyes are deaf; 40 percent of &quot;odd-eyed&quot; white cats with one blue eye are deaf; and 65 to 85 percent of blue-eyed white cats are deaf.&quot;&lt;ref&gt;{{cite book |last=Richards |first=J. |url=https://books.google.com/books?id=7JCTRdg68tIC&amp;pg=PA71 |title=ASPCA Complete Guide to Cats: Everything You Need to Know About Choosing and Caring for Your Pet |publisher=Chronicle Books |date=1999 |isbn=9780811819299 |page=71}}&lt;/ref&gt;

In one 1997 study of white cats, 72% of the animals were found to be totally deaf. The entire [[organ of Corti]] in the [[cochlea]] was found to have degenerated in the first few weeks after birth; however, even during these weeks no brain stem responses could be evoked by auditory stimuli, suggesting that these animals had never experienced any auditory sensations. It was found that some months after the organ of Corti had degenerated, the [[spiral ganglion]] of the cochlea also began to degenerate.&lt;ref name=Heid&gt;{{cite journal|last1=Heid|first1=S|last2=Hartmann|first2=R|last3=Klinke|first3=R|title=A model for prelingual deafness, the congenitally deaf white cat—population statistics and degenerative changes|journal=Hearing Research|date=January 1998|volume=115|issue=1–2|pages=101–12|doi=10.1016/S0378-5955(97)00182-2|pmid=9472739|s2cid=38262220}}&lt;/ref&gt;

BAER-testing ([[Brainstem auditory evoked response|Brainstem Auditory Evoked Response]]) is used to test deafness in cats.&lt;ref&gt;{{cite journal |last1=Webb |first1=Audrey |title=Brainstem auditory evoked response (BAER) testing in animals |journal=Canadian Veterinary Journal |date=March 2009 |volume=50 |issue=3 |pages=313–318 |pmid=19436486 |pmc=2643461 }}&lt;/ref&gt;

==Genetics==
Although few studies have been done to link this to genes known to be involved in human [[Waardenburg syndrome]], a syndrome of hearing loss and depigmentation caused by a genetic disruption to [[neural crest]] cell development, such a disruption would lead to this presentation in cats as well.&lt;ref&gt;{{Cite journal|last1=Omenn|first1=Gilbert S.|last2=McKusick|first2=Victor A.|last3=Gorlin|first3=Robert J.|date=1979|title=The association of Waardenburg syndrome and Hirschsprung megacolon|journal=American Journal of Medical Genetics|language=en|volume=3|issue=3|pages=217–223|doi=10.1002/ajmg.1320030302|pmid=484594|issn=1096-8628}}&lt;/ref&gt; Waardenburg syndrome type 2A (caused by a mutation in ''[[MITF]]'') has been found in many other small mammals including dogs, [[minks]] and mice, and they all display at least patchy white depigmentation and some degeneration of the cochlea and [[saccule]], as in deaf white cats.&lt;ref&gt;{{Cite journal|last1=MARKAKIS|first1=MARIOS N.|last2=SOEDRING|first2=VIBEKE E.|last3=DANTZER|first3=VIBEKE|last4=CHRISTENSEN|first4=KNUD|last5=ANISTOROAEI|first5=RAZVAN|date=1 August 2014|title=Association of MITF gene with hearing and pigmentation phenotype in Hedlund white American mink (Neovison vison)|journal=Journal of Genetics|language=en|volume=93|issue=2|pages=477–481|doi=10.1007/s12041-014-0370-3|pmid=25189243|issn=0973-7731|hdl=10067/1211550151162165141|s2cid=16725018|hdl-access=free}}&lt;/ref&gt;&lt;ref&gt;{{Cite journal|last=Strain|first=George M.|date=2015|title=The Genetics of Deafness in Domestic Animals|journal=Frontiers in Veterinary Science|language=en|volume=2|page=29|doi=10.3389/fvets.2015.00029|pmid=26664958|pmc=4672198|issn=2297-1769|doi-access=free}}&lt;/ref&gt;

A major gene that causes a cat to have a white coat is a dominant masking gene, an [[allele]] of [[KIT (gene)|''KIT'']] which suppresses pigmentation and hearing. The cat would have an underlying coat colour and pattern, but when the dominant white gene is present, that pattern will not be expressed, and the cat will be deaf. A cat that is homozygous (WW) or heterozygous (Ww) for this gene will have a white coat despite the underlying pattern/colour. A cat that lacks this dominant masking gene (ww) will exhibit a coat colour/pattern.&lt;ref&gt;{{Cite journal|last1=David|first1=Victor A.|last2=Menotti-Raymond|first2=Marilyn|last3=Wallace|first3=Andrea Coots|last4=Roelke|first4=Melody|last5=Kehler|first5=James|last6=Leighty|first6=Robert|last7=Eizirik|first7=Eduardo|last8=Hannah|first8=Steven S.|last9=Nelson|first9=George|last10=Schäffer|first10=Alejandro A.|last11=Connelly|first11=Catherine J.|date=1 October 2014|title=Endogenous Retrovirus Insertion in the KIT Oncogene Determines White and White spotting in Domestic Cats|journal=G3: Genes, Genomes, Genetics|language=en|volume=4|issue=10|pages=1881–1891|doi=10.1534/g3.114.013425|issn=2160-1836|pmid=25085922|pmc=4199695}}&lt;/ref&gt; ''KIT'' mutations have also led to patchy depigmentation and different coloured irises in humans,&lt;ref&gt;{{Cite journal|last1=Hamadah|first1=Issam|last2=Chisti|first2=Muzamil|last3=Haider|first3=Mansoor|last4=Al Dosssari|first4=Haya|last5=Alhumaidan|first5=Rawan|last6=Meyer|first6=Brian F.|last7=Wakil|first7=Salma M.|date=13 July 2019|title=A novel KIT mutation in a family with expanded syndrome of piebaldism|journal=JAAD Case Reports|volume=5|issue=7|pages=627–631|doi=10.1016/j.jdcr.2019.01.021|issn=2352-5126|pmc=6630042|pmid=31341943}}&lt;/ref&gt; and ''KIT'' has been found to increase ''MITF'' expression, the gene involved in human Waardenburg syndrome type 2A.&lt;ref&gt;{{Cite journal|last1=Lee|first1=Youl-Nam|last2=Brandal|first2=Stephanie|last3=Noel|first3=Pierre|last4=Wentzel|first4=Erik|last5=Mendell|first5=Joshua T.|last6=McDevitt|first6=Michael A.|last7=Kapur|first7=Reuben|last8=Carter|first8=Melody|last9=Metcalfe|first9=Dean D.|last10=Takemoto|first10=Clifford M.|date=31 March 2011|title=KIT signaling regulates MITF expression through miRNAs in normal and malignant mast cell proliferation|journal=Blood|volume=117|issue=13|pages=3629–3640|doi=10.1182/blood-2010-07-293548|issn=0006-4971|pmc=3072881|pmid=21273305}}&lt;/ref&gt;

=== Non-deaf blue-eyed white cats ===
The established link between deafness and blue eyes is found in the link between deafness, blue eyes, and solid white coats. However, it is a common misconception that all white cats with blue eyes are deaf.&lt;ref&gt;{{cite book |first=George M. |last=Strain |url=https://books.google.com/books?id=clmDR0wFtKkC |title=Deafness in Dogs and Cats |publisher=[[CAB International]] |date=2011 |isbn=9781845937645 |pages=[https://books.google.com/books?id=clmDR0wFtKkC&amp;pg=PA68 68]}}&lt;/ref&gt; It is possible to have a cat with a white coat without this gene as an extreme form of [[Cat_coat_genetics#White_spotting_and_epistatic_white|white spotting]], though this is rare; some small non-white patch usually remains. 

Furthermore, there are multiple genes responsible for blue eyes, and several of these genes are not linked to masking, white coats or deafness, such as the dominant blue eye (DBE) gene carried by [[Ojos Azules]]. Another example is a mutation in the [[Tyrosinase|TYR gene]] causing [[Points (coat color)|point coloration]], a form of partial albinism seen in [[Siamese cat|Siamese cats]] and related breeds. [[Foreign White]] cats, a white variation of Siamese, are also not prone to deafness.{{Citation needed|date=February 2025}}

== In popular culture ==

* The character Snowkit in the [[Warriors (novel series)|Warriors series]] book ''[[A Dangerous Path]]'' has congenital sensorineural deafness.&lt;ref&gt;{{cite book |last=Hunter |first=Erin|title=A Dangerous Path|date=17 March 2015 |publisher=Harper Children's|page=79-81|isbn=9780062367006}}&lt;/ref&gt; His condition leads to his death as he fails to hear his mother's warning of the appearance of a predator.&lt;ref&gt;{{cite book |last=Hunter |first=Erin|title=A Dangerous Path|date=17 March 2015 |publisher=Harper Children's|page=94|isbn=9780062367006}}&lt;/ref&gt;

== See also ==
*[[Cat coat genetics]]
*[[Merle (dog coat)]]
*[[Pleiotropy]]
*[[Van cat]]
*[[Waardenburg Syndrome|Waardenburg syndrome]]

==References==
{{reflist}}

{{Cat nav|state=collapsed}}

[[Category:Cat diseases]]
[[Category:Deafness]]
[[Category:Hair color]]