Inherited deafness in one or both ears occurs due to the degeneration of sensory inner ear structures (sensorineural deafness) within a few weeks of birth. This occurs in many breeds and is especially common in the dalmatian.

    The trait for deafness is tied to the genetics of coat colour, particularly in breeds with the merle or piebald gene. There is an increased risk of deafness with increasing amounts of white in the coat.

    How is deafness inherited?

    The mode of inheritance in dalmatians is thought to be autosomal recessive involving more than 1 gene (or incomplete penetrance may be involved), since dogs with normal hearing in both ears can produce bilaterally deaf puppies, and vice versa.
    Dogs with deafness in 1 ear can have pups that are deaf in both or neither. Statistically however, deaf parents are more likely to produce deaf pups.

    Dogs with an increased amount of white in their coats and blue eyes (discussed further below) are predisposed to congenital deafness. In breeds in which deafness is associated with merle colour, the trait appears to be autosomal dominant.

    In the bull terrier, Doberman pinscher, pointer and rottweiler, congenital deafness is thought to be an autosomal recessive trait.

    What breeds are affected by deafness?

    Deafness occurs in many breeds. The highest incidence is in the dalmatian, with studies from the US and the UK showing that 18 to 30% are unilaterally deaf, and 5 to10% are bilaterally deaf. The condition is slightly more common in female dalmatians.
    Other breeds with a relatively high incidence of deafness are the English setter, Australian shepherd, border collie and Shetland sheepdog.

    There is a strong association of deafness with increased amounts of white colour in the coat and blue eyes (heterochromia iridis) in breeds with merle and piebald coat colouring. Merled breeds include the merled collie and Shetland sheepdog, Australian heeler, dapple dachshund (18% bilaterally deaf, 36% unilaterally deaf), harlequin    great Dane, Norwegian dunkerhound, and old English sheepdog. Breeds with the piebald gene (which affects the amount and distribution of white areas) include the beagle, bull terrier, samoyed, great Pyrenees, Sealyham terrier, greyhound, English bulldog, English setter, and of course dalmatian.

    Congenital deafness is reported less commonly in many other breeds including the akita, cocker spaniel, Staffordshire terrier, Boston terrier, boxer, Catahoula leopard dog, Doberman pinscher, dogo Argentina, English springer spaniel, foxhound, German shepherd, greyhound, Jack Russell terrier, Kuvasz, Maltese terrier, miniature
    pinscher, miniature and toy poodle, papillon, Rhodesian ridgeback, rottweiler, St. Bernard, Scottish terrier, Shropshire terrier, Siberian husky, Walker American foxhound, West Highland white terrier, whippet.

    For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

    What does deafness mean to your dog & you?

    Pups lose their hearing a few to several weeks after birth. Signs of bilateral deafness may include aggressive play because the deaf pup does not hear cries of pain from littermates, and having to be jostled to waken. Unilateral deafness is much harder to spot.

    If your dog is deaf in only 1 ear, you will likely not even be aware of it. In training sessions, you may notice that your dog responds better to hand signals than verbal cues.

    One-sided deafness is generally not a problem, except in some working dogs for whom localization of sound is important. However it is much more difficult for bilaterally deaf dogs to lead a normal life, and breeders will generally opt for euthanasia of these pups.

    How is deafness diagnosed?

    If you suspect your dog is deaf, your veterinarian will recommend the BAER (Brainstem Auditory-Evoked Response) test since hearing loss can be very difficult to evaluate by clinical examination (ie. behavioural response to sounds). The BAER test is a painless and reliable means of detecting hearing loss in one or both ears, that is     available at veterinary schools and referral centres. It can be used in puppies of 5 weeks of age on. Older pups and adult dogs may need to be sedated for the test.

    Dogs in breeds with a high incidence of deafness should be tested by the BAER test before being used for breeding, and pups should be tested before being sold. Hearing loss, if present, is complete - that is the dog either has normal hearing, or is totally deaf in 1 or both ears.

    How is deafness treated?

    Deafness can not be cured or treated, but dogs can generally accommodate very well, particularly if only deaf in 1 ear. They should not be bred.

    Because dogs that are deaf in both ears startle easily, are difficult to train, and are prone to accidents, they are usually euthanized as pups. As an alternative, an owner may train the dog to respond to hand signals or other visual cues, always restrain him/her on a leash or in a fenced yard, and be alert to the possibility of the dog biting someone if startled.

    Breeding advice

    Controlled breeding can reduce deafness. Any dalmatian to be used for breeding should be checked by the BAER test. Pre-breeding BAER screening should also be used in other breeds where congenital deafness is a problem. Bear in mind that dogs who are deaf in 1 ear appear to function normally, but they should not be used for breeding as this contributes to the perpetuation of this disease.

    There is a lower incidence of deafness in dalmatians in Norway and the UK, likely due to selection by breeders against blue eyes, which are considered a desireable feature in the US.

    Well-defined and publicized screening programmes and registries of dogs used for breeding will help to reduce the incidence of deafness. The Institute for Genetic Disease Control in Animals maintains an open registry for deafness, for all breeds.
    http://www.vetmed.ucdavis.edu/gdc/gdc.html

    It is laudable that dalmatian breed clubs, particularly in the UK, have supported research aimed at reducing deafness through assistance with funding and data collection.

    FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

    Resources

    Ackerman, L. 1999. The Genetic Condition: A Guide to Health Problems in Purebred
    Dogs. pp 132-133. AAHA Press. Lakewood, Colorado. This reference has a good
    explanation of the heredity of the deafness trait and the association with
    merle and piebald coat colours.

    Wood, J.L.N., Delauche, A.J., Lakhani, L.H. 1996. The problem of inherited disease 6:
    deafness in Dalmatians. J. of Small Animal Practice. 37(11) : 559-561.