**Jack Fact**
Owners of deaf dogs can find advice through resources. They can be found on the links page under Deaf dog resources!
Deafness in Dogs
Hereditary pigment-related deafness is the most common cause of deafness in young dogs. This condition is often linked to genes that affect pigmentation in the coat, iris, and other body parts.
A significant gene involved is the extreme piebald (sw) allele, predominantly found in white Jack Russell Terriers (JRTs). Affected dogs may be deaf in one ear or both, but they do not exhibit partial deafness in one ear.
The inheritance of this condition is complex: puppies from normal hearing parents can still be deaf, while those from bilaterally deaf parents may have normal hearing. However, it is generally observed that deaf dogs are more likely to produce deaf offspring compared to those that can hear.
The correlation between coat color and deafness goes beyond coincidence. Animals with alleles that create a lack of pigmentation in their coat and other visible body structures may also experience pigment deficits in certain internal structures.
For instance:
Healthy blood vessels contain pigment-producing cells called melanocytes, which play a crucial role in normal development. Dogs with the (Sw) alleles appear to have melanocyte-deficient blood vessels leading to the inner ear. These dogs are born with structurally normal auditory components; however, shortly after birth, the blood vessels begin to degenerate. This degeneration affects parts of the inner ear, including the hair cells essential for hearing, resulting in complete deafness by around one month of age.
Diagnosis
In dogs with normal hearing, auditory signals travel from the ear to the brain via the brainstem. The Brainstem Auditory Evoked Response (BAER) test measures the brainstem's electrical activity in reaction to sounds, providing valuable insights into whether a dog’s hearing is functioning correctly. This pain-free test can be performed on awake dogs. Given that deafness in Jack Russell Terriers (JRT) typically becomes apparent by two to three weeks of age, it's essential for all puppies to undergo BAER testing before being placed in new homes. Responsible breeders should routinely test their breeding stock and refrain from breeding any dogs identified as deaf.
While some preliminary hearing screening tests can be conducted at home, they often lack accuracy and can only identify dogs with bilateral deafness. A simple preliminary test involves speaking a word that usually captures the dog's attention while the dog is distracted and unable to see the speaker. Another approach is to ring a bell or create an unexpected sound from behind the dog, which should elicit a response—such as turning the head or twitching the ears—or even a startle reaction.
Additionally, if a dog that is panting suddenly pauses to listen, this can serve as a tentative indicator of hearing ability.
Check your dog's hearing by watching their reaction to noises from hidden sources.
Testers must ensure that no wind currents from clapping hands or vibrations from the floor reach the dog. Additionally, the dog should not be able to see the tester out of the corner of its eye—keeping in mind that dogs have a much wider peripheral vision than humans. It's also important that the dog does not see the tester's shadow or reflection.
Any other dogs that could provide cues through their reactions should be removed from the area to avoid distractions.
Dogs tend to habituate quickly to sounds, so repeating the test may lead to diminished responsiveness. These tests are typically effective in identifying dogs that are deaf in both ears. However, a dog that is deaf in one ear may still react to words and sounds in a way that is nearly indistinguishable from a dog with normal hearing.