On Deaf Ears

Science is coming to the aid of deaf dogs and cats with better diagnostic protocols and even the installation of pet hearing aids being possible.

Deaf pets can be difficult to manage. With the inability to hear their owners or to detect dangers such as approaching motor vehicles, deaf dogs and cats need dedicated and caring owners.

How does deafness occur in pets?

Deafness can occur by two processes.

Sometimes dogs and cats have congenital deafness, meaning they are born deaf, or deafness develops within a month after birth.

In an American study, Dalmatians topped the list with almost 30% of over 5,000 of the breed showing some form of deafness. White bull terriers show a 20% incidence of deafness, Australian cattle dogs have a 14% incidence and English setters approximately 12%.

White cats are also particularly prone to deafness. A collection of studies in the 70s and 80s showed that 50% of white cats show some degree of deafness. The incidence of deafness is as high as 85% in white cats with two blue eyes, and 40% in cats with just one blue eye (these cats are commonly called odd-eyed whites).

Other pets develop deafness (called acquired deafness) 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.

Can Hearing Be Tested in Pets?

While it is a lot more difficult to test the hearing of a pet compared to humans, it is not impossible.

A test called the Brainstem Auditory Evoked Response (BAER) has been developed to test the hearing capabilities of dogs. This test is used at the University of Queensland by Dr Sue Sommerlad and by other professionals in locations around Australia and overseas.

This test can be used on puppies from the age of six weeks, and is therefore useful for testing those litters of breeds with a high prevalence of congenital deafness.

In a BAER test, three small needle electrodes are placed under the skin in the scalp of the dog. The electrodes detect electrical conductivity in the inner ear and in the auditory pathways in the brainstem in much the same way an ECG detects electrical activity from the heart. The electrical activity in response to a sound is identified by waves and peaks on a graph. A trace with no peaks indicates deafness in the ear being tested and will even show whether a dog is deaf in just one ear or in both.

Can Deafness Be Treated?

It is important that your veterinarian examines your pet if it develops deafness.

Some forms of deafness are treatable and because ear infections are such a common cause of deafness, it is important that infections are treated.
But what about hearing aids for deaf pets? Dr Sommerlad from the University of Queensland works with Ms Deborah Mackenzie, the head of audiology from the Royal Brisbane Hospital. This team pioneered research to develop the first hearing aid for dogs.

These candidate dogs were those that suffered conductive deafness after damage to or removal of their ear canals.  The hearing aid is implanted into the bone near the ear and transmits vibrations into the inner ear. The vibrations are then converted into signals sent to the brain.

Until recently this procedure had been limited by the thickness of the bone which holds the implant. This is important as younger animals may not have thick enough bone to house the implant.  Dr Sommerlad’s recent work has shown that by using bone grafts to thicken the bone, the implants can be fitted to younger animals.

This same technology can be sued to facilitate the placement of implants in deaf children under five, allowing them to hear at an earlier age.

Training a Deaf Dog

It is certainly possible to train a deaf dog, and even a deaf cat, but it takes patience and commitment. You need to use hand commands and to be very consistent in the way you use them. Also exaggerate your facial expressions so the dog can easily tell right from wrong and when you are happy with it and when you are not.

To get a deaf dog or cat’s attention stamp on the floor, throw a stuffed sock or a ping pong ball near it. If you are outside toss a small pebble or rock near the pet. Then give it the appropriate hand signal.

Develop a special way to rouse your deaf dog from a sleep. A deaf pet can startle easily when asleep and this can cause aggression and fear. Try waking your dog by putting your hand in front of its nose or by using the scent of a food treat.

Pethealth Articles Available

Dr Cam Day

Dr Cam Day

Vet Behavioralist

Dr Cam Day is a Veterinarian consulting full-time in pet behaviour in South-East Queensland, Australia.