Deafness is not an uncommon problem for dogs. Congenital deafness has been reported for approximately 80 breeds, with the list growing at a regular rate it can virtually appear in any breed. For the person seeking to buy or adopt a pet, failing to check for deafness can cause unexpected hardships and may ultimately end the relationship. Deafness can occur by two processes. Sometimes dogs have congenital deafness, meaning they are born deaf, or deafness develops within a month after birth. Other dogs develop deafness (called acquired deafness) at any time later in life. This can occur due to the use of drugs, particularly some antibiotics, from noise trauma, ear infections and from age-related hearing loss. The current common way that most veterinarians test for deafness is behaviorally, by making a loud noise and then observing the dog’s behavior. While this seems to be a foolproof method, there are inherent weaknesses to this casual examination. Dropping a large book may convince you that the dog actually "heard" a sound. In reality, he may have felt the vibration of the floor, through the pads of his feet. Banging pots and pans together may also prove futile. A puppy that has spent its life devoid of sound often learns to constantly scan for visual cues. If the puppy perceives a subtle change in ambient light, shadows or peripheral movement, as you bang a pot, it may still beat the loud noise test.
A better way to test hearing is to perform an Auditory Brainstem Response (ABR) in conjunction with an Otoacoustic Emission test (OAE). An ABR is an objective and quantitative test that measures the electrical potential produced by the brain in response to sound stimuli by the synchronous discharge of the neurons in the auditory nerve and brainstem.. Instead of being determined by behavior, the ABR is an efficient, objective, and quantitative way to determine if there is a complete or partial hearing loss in a dog. The ABR is regularly performed in humans to assess hearing function and to predict or identify other medical issues related to neural and/or otological function and would be a valuable tool to use in canines as well.
It is very important to be able to accurately determine if there is a complete or partial deafness because there is a greater likelihood of death from being hit by cars because of the inability to hear the vehicles coming. Dogs who cannot hear can be more prone to injuries, since they cannot hear commands or objects coming towards them. There are also behavioral concerns. A deaf dog can startle easily when asleep and this can cause aggression and fear. This research is very significant in that its outcome will be used to more efficiently determine if there is a hearing loss in dogs and will allow us to improve the quality of living of deaf dogs and their owners.
Presently Auditory Evoked Potential (AEP) testing and evaluation is not taught in veterinary medicine. It is hope d that animal audiology will emerge in a similar manner as has been embraced by the human medical community. The relationship of the “animal audiologist” to the veterinarian can be the same as the relationship of the human audiologist to the (ear-nose and throat specialist) ENT medical doctor. Once we are able to accurately determine if there is a hearing loss, we can now move on to proper breeding, training, and handling of deaf dogs and potentially aid in eliminating genetic and sensorineural hearing loss in dogs. The impact of establishing canine “normative data” will be a tremendous advancement in animal welfare and veterinary medicine.