BRAINSTEM AUDITORY EVOKED RESPONSE
The hearing test known as the BAER (brainstem auditory evoked response) detects electrical activity in the inner ear and the auditory
pathway in the brain.
The BAERCOM is a quick and non-invasive test that can diagnose deafness in dogs and cats.
Some breeds carry a piebald / merle gene associated with deafness , for some breeds congenital deafness (from birth) is more common. These breeds include Dalmatians, English Bull Terriers, Border Collies and cats which have white coats (especially those with blue eyes).
The youngest age the test can be performed at is 5 weeks for puppies and 8 weeks for kittens. This is because the ear canals are not open until roughly 12-14 days of age so sound waves cant enter the ear.
There is no upper age limit for the BAER test being performed.
BAERCOM TEST uses three small acupuncture needles placed under the skin:
One in front of the ear
One on top of the head
One centrally on the forehead
These generally don’t hurt when placed.
A headphone is placed over the ear being tested that produces a sound wave in a pattern of ‘clicks’.
Sound waves enter the external ear, which travel down within the inner ear canal. The sound waves reach the eardrum which then begins to vibrate. These vibrations move into the middle ear causing the tiny bones (auditory ossicles) to vibrate.
The vibration waves move to the cochlea in the inner ear. Hair cells within the cochlea begin to move or ‘wave’ due to the change in pressure.
The cochlea is connected to the auditory nerve which then triggers an impulse that is registered by the brain.
In ‘normal’ hearing the BAER test graph will show a number of peaks and troughs which are displayed on the screen.
This then generates a computer graph measuring brain wave response to the sound allowing us to assess the hearing.
Once both ears have been tested the computer will print the graph and certificate which will be signed for you to take away.
The BAER test can identify whether the animal is deaf in one ear (unilateral deafness) or both ears (bilateral deafness).
There is no ‘partial’ deafness in these cases.
There are different types of deafness that can affect dogs and cats:
Unilateral deafness - hearing loss in one ear
Bilateral deafness - hearing loss in both ears
Age related deafness - progressive hearing loss related to age
Unilaterally and bilaterally deaf dogs can make excellent pets, however if bilaterally deaf, correct specialist training is required.
It is inadvisable to breed from unilaterally or bilaterally deaf animals, as this may be passed down through generations.
All test results are confidential. Two hardcopy certificates of the test results are provided for each puppy for your records and or for your
new puppy owner.
What Do I Do If My Pet Is Deaf?
Please feel free to discuss any worries with your VET and speak to their hearing clinic nurse who will always be happy to provide any further advice you might require.
For puppies that fail their hearing tests we recommend
Hear, Hear!: A Guide to Training a Deaf Dog by Barry Eaton