Deafness : white cat’s curse





We would not be wrong to say that Turkey is a country with the largest number of white cats.
White cats are considered as the "national breeds" and desirable pets, however people are not aware of deafness issue affecting lives of so many white cats. In contrary, colored cats don’t have such a problem.
The breeding of the white cats is practiced in the Ankara Zoo and the Van University. Both of these institutions see their so called breeds as solid white and preferably having odd – eyes. In fact, deafness in the Angora cats seen as a normal phenomenon, while Van university confidently claims, that their cats have only 2-3 % deafness rate. This is, of course, impossible. Van University has never done even one single study on deafness of white cats and never performed any serious hearing tests.

The Ankara Zoo does nothing to prevent deafness which occurs in alarmingly high numbers: 7 out of 9 cats were deaf in one ear (Tike, 2009).

However the deafness problem should a very serious concern for everybody who loves and care about the cats. Deaf cats are vulnerable to various dangers. Behavior problems like, aggression are quite common with white deaf cats. Deaf cats may not make the good pets.

Deafness is a disability which definitely harms the cats. Fortunately there are ways that reduce deafness occurrence significantly or even may prevent it completely.


1. What makes my cat’s fur white?

No matter how strange it sounds, your cat only appears white, because the gene W (white) acts as a mask, covering all other colors cat may have (Robinson, 1977).  Besides white cats are not albinos!

2. My white cat has a colored spot on the head? What is this?

It’s normal and happens in the white cats. The patch of color on your cat’s head shows off the color a cat hides under its white fur. It will fade away with age. It was observed that a cat with a patch on head is less deaf than those without (Robinson, 1977), however more evidence is needed.

3. Do longhair cats have the bigger chance to be deaf?

Some researchers (Mair, 1973) suggested that longhair cats tend to be deaf more frequently than shorthair cats. This is not truth! The long or short fur has no relation to deafness. Both longhair and shorthair cats can be deaf if they are solid white.


4. Do deaf cats can’t hear at all?

Not true, some may hear with one ear but not another (Rebillard et al., 1981a). There two kind of deafness: Unilateral which affects one ear and bilateral - effects both ears, which means a cat is completely deaf.
In very rare cases, a cat may have partial loss of hearing, but even electrodiagnostic tests have limited efficiency for this type of diagnosis and should be used with caution (Strain GM, 1997).

5. Can deafness be inherited?

Yes, cats with the white fur often will be born deaf. It’s called congenital deafness (Strain GM, 1999).
This deafness is similar to Waardenburg syndrome (Bergsma, Brown, 1971; Webb, 2010) seen in humans which make them deaf and their skin, eyes and hair pale.


6. Are all blue eyed white cats always deaf?


Not always, but many are. If a cat has blue eyes, the chance of being deaf is very high compared to cats with amber or green eyes (Geigy, 2007). Analogically, odd-eyed cat may be deaf in the side of blue eye.

7. Why some white cats are deaf and others are not?

Deafness in white cats is a complex matter. It correlates to the white fur and especially blue eyes, however not all white cats with blue eyes are deaf. So there are additional factors. It’s a polygenetic issue (Strain GM, 2007). There are many unidentified genes responsible for causing deafness and we haven’t find them out yet.

8. Is deafness a characteristic of the Angora cats?

No!
Some people think it a proof that the Angora is ‘’purebred’’, but deafness is not something we should be proud of. It’s a disability seen in many white cats! Besides only white Angoras can have this problem, while colored Angoras will not be deaf! The stereotype that Angora cats tend to be deaf, will get a confirmation from "white to white" breeding practices  and won’t vanish easily on its own.


9. Do Van cats have only have 2-3 % of deafness?

This is a myth, very much like the prevalent belief "Van cats like to swim" (based on anecdotes and stories). Nobody has ever done even one study about the deafness of white cats from the Van cat house.Why deafness is not taken seriously? It seems that the Van cat research center is satisfied with an opinion (Odabaşiolu Ateş, 2000) and prefer to avoid this matter at all costs. The truth is, so called Van cats are affected by deafness like any other white cat.
Giving a special status for the white cats as a "special breed" we not only segregate cats purely by our flawed thinking, but also create more deaf animals. All of this is preventable and cannot be justified.

10. Is it possible that my cat was not deaf at first and later lost its hearing?


Unless your cat’s deafness is caused by physical factors like infection, damage to ears or old age, your cat will not lose its hearing suddenly for no reason. White cats which are deaf since birth in one or both ears, won't have its hearing improved or worsened, but will stay constant for the rest of their lives (Ryugo et al., 2003).




11. Could a deaf cat ever hear again? Is there any treatment available?

Maybe. According to the latest research(Chen, Ruygo, 2010), deaf kittens which got cochlear-implant (made specially for cats) implanted at early age, had their hearing partially restored. These cats from the study not only offering a promising treatment for other deaf cats, but also serve as a perfect model for studying and treating deafness in children.


12. Do deaf cats, just like deaf people, are blessed with better vision compared to hearing cats?

Partially. Deaf cats brain compensates its lost hearing with somewhat improved. A deaf cats can understand better how fast an object is moving (visual motion detection) and their wider than normal cats, vision field allows understand how far an object is (peripheral vision).
The other visual abilities are however not different than those of hearing cats vision (Lomber, 2010).


13. What are known behaviour problems in deaf cats?

-Deaf cats are more sensitive to stress and changes and show almost paranoid like behaviors (hyper-alertness) (Beaver, 2003). According to reports of veterinarians, deaf cats tend to be more aggressive and harder to handle during veterinary visits.
-Vocalizations of deaf animals may be louder than normal (Strain GM, 2011), so some owners may complain their cats being too noisy and talkative.
-Deaf females are less good mothers, may not meet the needs their kittens, because unable to hear their cries (Beaver, 2003).
-Challenging to keep as pets. Completely deaf cats can not respond to any vocal commands, so owners should be prepared that having a deaf cat will need some knowledge and effort in order to communicate with their cats. There are already some techniques used to train deaf dogs which could be useful for cats too.
-Susceptible to dangers outside: deaf cats must be kept indoors only. The risk of being hit by the car is high(Strain GM, 2011).

14. My cat has some color on its head and tail but is otherwise all white. Can it be deaf also?


No, your cat is not white because of W gene, found in most of white cats. A cat which is not completely white  (bicolor) is result of another unrelated gene (Cooper et al., 2005) - white spotting (S). This gene are not associated with deafness.

15. I want to breed my two white cats. What is the chance that kittens will be deaf?

You should think twice before you breed any white cats. Is it worth to risk at the expense of cats health and well-being?
Are you sure your cat is not deaf? What if it can’t hear with one ear? It doesn’t matter if a cat you want to use for the breeding is completely or just partially deaf – NEVER breed any deaf cat, if you do not want to bring more deaf kittens to this world.

At least 50 % of white cats will be deaf (Delack, 1984), while blue eyed cats will 65- 85 % at risk, with one blue eye has risk about 40 % and cats with no blue eyes - 20 % (Mair 1973, Bergsma and Brown 1971).
In conclusion, there is a very high risk that kittens will be deaf, if you breed two white cats.


16. Do pedigreed cats have a lower incidence of deafness?

One study (Cvejik D, 2009) tested 55 white pedigreed cats, from which 22 % (17) were deaf; about half of blue eyed cats were deaf.
Pedigreed cats may be less deaf because white cats are often mixed with Siamese colored cats (temperature-sensitive albinism; Imes et al., 2005). They will be white, will have blue eyes but genetically will be pointed (Pedersen, 1991) therefore NOT deaf.


17. Are albino cats also deaf?

No, albino cats are not deaf. An experiment of breeding Siamese cats showed that from 20 cats across five generations, not even one cat was deaf. It was confirmed by the auditory brainstem response (ABR) test (Creel, 1982).

Albino cat and a white cat are unrelated; besides albinos are rare. Pointed color seen in Siamese cats is a type of albino. Cats which carry Siamese color (cs gene) can have blue eyes, white fur and no deafness (Pedersen, 1991).
 
BAER test


18. I have a white cat and it’s not deaf.

Good for you, but are you sure it hears with both ears? Observing a behavior and reactions of your cat is not reliable way to understand deafness (Strain, 1999). It could easier to spot a completely deaf cat (bilateral), but you will miss a cat which hears with only one ear. The only way to know if your cat is 100 % hearing is to do electrodiagnostic tests (BAER, BAEP, ABR).
Unfortunately, a  limited availability of BAER testing sites, create difficulties and may be out of reach for many cat owners.This problem should be addressed.

19. How can I reduce the risk of deafness?

  •   Don't breed two white cats. Make sure one of parent’s will be colored. You can expect that almost all kittens will be white even if one parent is colored and the other one is white. This is because a white color is dominant over all other colors.
  • Breeding white and colored cats is not a cure, and may still produce white and deaf kittens. On the other hand, the risk will be significantly  lower: only 25 % on average (Bergsma and Brown, 1971; Mair, 1973) were deaf compared to almost 50 % deafness rate in kittens from both white parents (Delack, 1984). Many cat breeders today only breed white cats with colored ones and significantly reduce the number of kittens with hereditary deafness.
  • Don't breed any cats which are deaf (Strain, 2011). Don't rely on your senses - a cat may be deaf in one ear and the only reliable way to know this is to test ALL white cats for deafness with electrodiagnostic test (like BAER).
  • Avoid breeding blue eyed cats (Robinson, 1977).



Sources:

1. Tike Şeyda, 2009, Yüksek Lisans Tezi, 47 sayfa, Ankara Kedilerine İşitme Testlerinin Uygulaması Ve İşitme Seviyelerinin Değerlendirilmesi, Sağlık Bilimleri Dergisi 18(3)I- LXVI
2. Robinson R., 1977, Genetics for Cat Breeders, Second Edition, London: Pergamon Pres
3. Mair, I.W. and Elverland, H.H. (1977) Hereditary deafness in the cat. An electron microscopic study of the stria vascularis and Reissner's membrane. Archives of Oto-Rhino-Laryngology 217, 199-217.
4. Rebillard et al., 1981a Variability of the hereditary deafness in the white cat. I. Physiology.
5. Strain GM, 1997: Electrophysiological assessment of auditory function. Proc. 15th ACVIM Forum 15:617.
6. Strain GM, 1999, Congenital deafness and its recognition; The Veterinary clinics of North America. Small animal practice
7. Bergsma, D.R., Brown, K.S., 1971. White fur, blue eyes, and deafness in the domestic cat. Journal of Heredity 62, 171–18
8. Webb, Audrey et. Al.,2010 Coat color and coat color pattern-related neurologic and neuro-ophthalmic diseases
9. Geigy etc. 2007, Does a pleiotropic gene explain deafness and blue irises in white cats? The Veterinary Journal 173, 548-553
10. Strain GM,2007; Deafness in blue-eyed white cats: the uphill road to solving polygenic disorders. Comment on Vet J. 2007 May;173(3):548-53.
11. Odabaşioglu, Ateş, 2000, Van kedisi,  Yüzüncü Yil Üniversitesi, (sayfa 85)
12. Ryugo et al., 2003, Separate forms of pathology in the cochlea of congenitally deaf white cats.
13. Chen, Ruygo, 2010, The Effect of Cochlear-Implant-Mediated Electrical Stimulation on Spiral Ganglion Cells in Congenitally Deaf White Cats, Journal of the Association for Research in Otolaryngology
14. Lomber, 2010, Cross-modal plasticity in specific auditory cortices underlies visual compensations in the deaf, Nature Neuroscience
15. Beaver, 2003 Feline Behavior, Elsevier Science
16. Strain GM, 2011 Deafness in Dogs and Cats, CABİ publishing.
17. Cooper etc.  2006, White spotting in the domestic cat (Felis catus) maps near KIT on feline chromosome B1, Anim Genet.
18. Delack, J.B. (1984) Hereditary deafness in the white cat. Compendium on Continuing Education for the Practicing Veterinarian 6, 609-619.
19. Cvejik D, 2009 Unilateral and bilateral congenital sensorineural deafness in client-owned pure-breed white cats
20. Imes et al., 2005, Albinism in the domestic cat (Felis catus) is associated with a tyrosinase (TYR) mutation.
21. Creel D et al., 1982, Retinal projections in tyrosinase-negative albino cats.
22. Pedersen, N.C. (1991). Feline Husbandry. Goleta, CA: American Veterinary Publications.


Authors: Perla Aksoy, Batu Aksoy
Publication date: 2014, October



Other versions of this article:

Kedilerimizde Sağırlık (Türkçe - Turkish)

Evrim Ağacı: Beyaz Kedilerin Korkulu Rüyası: Sağırlık (Türkçe - Turkish)


Surdité, la malédiction des chats blancs (Français - French)


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