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Deaf Animals Scope
Many lower species of animals are "deaf" in the sense that they do not have organs developed for detecting sound waves. Among these are worms, mollusks, squids, octopi, and more. The issue of whether or not a species of lower animal can "hear" is often obscured by the fact that many of them can detect the vibrations of sound waves, without actually hearing the sound itself. For example, many insects can detect sound through various organs, not all of which are true "ears." Virtually all animals with ears can become deaf from illness, injury, or medical intervention. This document is limited to those animals that are deaf from hereditary causes or are naturally deaf. This document is divided into four sections:
Cat breeds with tendency to hereditary deafnessDeafness in cats has relatively little connection with specific breeds, and more with having all or mostly white fur (not albinos, which have pink eyes and are normally hearing. Hereditarily deaf cats with white coats have blue or yellow eyes.) Nevertheless, some breeds of cat do have higher rates of genetic deafness than others:
Dog breeds with tendency to congenital deafness
Deafness in dogs also has some correlation with whiteness in the dog's coat, but to a much lesser extent than with cats. The particular breed plays a greater role in the chance of a dog's having deafness. There is also a far larger number of distinct dog breeds (78) identified as having consistently higher numbers of congenitally deaf individuals than in other breeds:
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Those breeds listed in bold have relatively high prevalences of congenital (hereditary) deafness.
Dalmatians have the highest proven incidence of all, with 8% being born deaf in both ears and up to 22% deaf in one ear. English setters are second, averaging 2.3% bilaterally deaf; third are Australian cattle dogs at 2.1% bilaterally deaf; fourth place is split between bull terriers and English cocker spaniels at 1% each. Each of these breeds also has a higher occurrence of deafness in just one ear.
Jack Russell terriers have tested out with a 10.6% bilaterally deaf rate (plus 8.5% unilaterally deaf), and the Catohoula leopard dog has been tested to have an incredible 41.7% bilaterally deaf rate (plus 27.1% unilaterally deaf). However, it must be pointed out that the numbers tested in each of those two breeds are too low to be statistically significant (less than 50 individuals were tested), and those figures should not be trusted until a larger number of animals in those two breeds can be tested for a better statistical sampling.
Partial bibliography:
Deaf Dog Education Action Fund (DDEAF)
P.O. Box 2840
Oneco, FL 34264-2840
Santa Fe School for Deaf Dalmatians
P.O. Box 8921
Santa Fe, NM 87504
Dalmatian Club of America, Inc.
Information on deafness in other animals is scarce.
Armadillos: According to anecdotes, these are reported to all have very poor hearing.
Bears: The Maryland Zoo in Baltimore (formerly Baltimore Zoo) has a deaf polar bear named Alaska, 10 years old in 2003.
Birds: There is a report that an (unidentified) study found that deaf wild birds make bad parents, because they cannot hear their offspring calling for food. There are also unconfirmed reports of some pet birds being found to be deaf.
Ferrets: As with many other mammals, deafness in ferrets is fairly common in individuals having whiteness in their coats, though the whiteness need not be total. Many individual deaf ferrets have apparently normal coloration, with only small to tiny amounts of whiteness, often in obscure spots. The Waardenburg syndrome responsible for hereditary deafness in some humans has also been identified in ferrets. A Web site about deaf ferrets is http://www.geocities.com/wolfysluv/deaf.html.
Goats: There is a breed of milk goats called LaMancha, in which all individuals nearly or completely lack the external ear pinna (flap or cup). Contrary to popular impression, however, LaMancha goats are not deaf. They still have an external ear opening, normal inner ears, and hear just fine. For more on them, see http://www.ansi.okstate.edu/breeds/goats/LAMANCHA/.
Horses: Several deaf horses have been reported; a story on one is at http://clerccenter.gallaudet.edu/WorldAroundYou/mar-apr98/snoopy.html. Unfortunately, information is lacking on how this horse or others became deaf-whether from hereditary factors, illness, injuries, or other factors.
Llamas and alpacas: These animals, native to South America but used in North America for their wool or as pets or even as herd guards, often have hereditary deafness in white-fleeced individuals.
Mice: There is a strain of congenitally deaf laboratory mice (mutant strain dn/dn) that are used in some laboratory experiments related to deafness. One technical medical document referring to them is:
Minks: As with other mammals, there tends to be a correlation between white coats and deafness in minks. A medical document studying them is:
Octopi, squids, and cuttlefish (coleoid cephalopods): All are truly deaf, completely lacking any kind of acoustic receptors.
Sea lions: The Brookfield Zoo near Chicago, IL, has a deaf sea lion named Harley.
Snakes: In the early 1950s, there were newspaper reports that "research" had shown snakes to be completely deaf. This is incorrect. Although they have no external ear openings, snakes do have internal ears, and can hear some sounds although poorly.
There is an organization called Deaf Pets of America, operated by deaf man Steven G. Doleac, that functions as an agency for finding homes for unwanted deaf pet animals. DPOA can be contacted through Mr. Doleac at e-mail stephen.doleac@gallaudet.edu. For adopting deaf dogs, also contact Deaf Dog Education Action Fund (DDEAF) at http://www.deafdogs.org.
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