BAER Hearing Clinics
BAER (Brainstem Auditory Evoked Response) is a quick and non-invasive test which can diagnose deafness in dogs and cats. Pride Veterinary Centre offer hearing clinics to those who wish to breed or have concerns about an animal’s hearing. In some breeds congenital deafness (at birth) is more common. Some breeds may carry an extreme piebald gene which is associated with deafness. Such breeds include Dalmatians, English Bull terriers, Border Collies and cats which have white coats (especially those with blue eyes).
The Auditory System
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 then travel into the middle ear which causes the tiny bones (auditory ossicles) to vibrate. The vibration waves then move to the cochlea within 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 which is registered by the brain.
There are different types of deafness that can affect dogs and cats.
- Conductive Deafness - this can interfere with the movement of sound waves due to a foreign body/buildup of ear wax/a rupture of the ear drum or infection.
- Sensorineural Deafness - caused by damage of defect of the inner ear via the auditory nerve and cortex of the brain.
- Congenital Deafness - present at birth. Late onset deafness may also occur due to loss of hearing associated with old age.
- Inherited Deafness - passed down through parents to offspring. Acquired deafness is due to external factors such as injury, trauma or disease.
Deafness seen in some breeds of dogs and cats can occur due to degeneration of structures within the cochlea.
Pride Veterinary Centre can offer hearing tests to not only breeders, but to those animals with acquired deafness as a result from trauma, disease or old age.
BAER Test – What to expect
The BAER test is usually a quick and simple test which can provide a 'pass' or 'fail' result. Puppies can be tested from 6 weeks of age, and kittens from 8 weeks of age. The test usually takes less than half an hour per patient, however some dogs and cats become nervous and may need longer. It is advisable to withhold food eight hours before the procedure for older animals as they may need sedation. It is not advisable to sedate puppies or kittens.
On the day, the BAER test is carried out in a quiet consult room by a specially trained hearing nurse. A vet will then review the test and sign the certificate stating whether the pet has ‘passed’ or ‘failed’ the test. If arriving with a litter, we recommend that you bring a friend with you to help hold any wriggly patients! The practice will provide a crate with bedding and a fresh bowl of water for any thirsty travelers.
The best time for testing is when the litter has had chance to stretch their legs, had a drink and have then had a chance to relax on a nice soft bed. A relaxed and happy puppy will usually test much better.
The test involves placing 3 tiny needles subcutaneously (under the skin). One placed on top of the head, one positioned centrally on the forehead and one below the ear which is being tested. The needles are similar to acupuncture needles and generally do not hurt when placed. A headphone is then held over the ear being tested which releases a sound wave in a pattern of ‘clicks’, this then generates a computer graph measuring brain wave response to the sound allowing us to assess hearing. Once both ears are tested the computer graph is printed out for each patient, this graph is then attached to the signed certificate, which you can take away with you.
BAER Test Results
In ‘normal’ hearing the BAER test graph will show a number of peaks and troughs which are displayed on the screen. BAER testing 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. Unilaterally deaf dogs can make excellent pets, however, if bilaterally deaf correct specialist training is required. It is not however advisable to breed from unilaterally or bilaterally deaf animals, as this may be passed down through generations.
What to do if my animal is deaf?
Pride Veterinary Centre offers a number of canine training sessions which range from 'Puppy Obedience and Socialisation' through to 'Agility Training'. We also have a behaviorist that can help with any worries or concerns you might have. Please feel free to discuss any worries with your hearing clinic nurse who will always be happy to provide any further advice you might require.
To make an appointment regarding a BAER test, get directions or prices please call 01332 678 333.
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