What is BAER testing
Brainstem Auditory Evoked Response (BAER) testing is an electro-diagnostic test used to evaluate the hearing ability of dogs, cats, and other domestic animals. It evaluates the components of the external ear canal; the middle/inner ear cavities; cranial nerve and selected areas of the brainstem.
It is a non-invasive procedure taking from 5 to 15 minutes to perform for each patient. In some circumstances, sedation is used. If the hearing threshold needs to be determined, more often in older patients, general anesthesia is recommended.
From small subcutaneous electrodes and externally applied acoustic stimuli of different intensity, we record numerous waves, each of which represents composite neuronal activity.
What are the uses of BAER testing?
1. Early diagnosis of hearing loss secondary to cochlear agenesis/degeneration.
2. Assessment of brainstem (caudal part of the brain) function.
3. Conductive hearing loss which is the result of a dysfunction of the external ear canal and middle ear space.
4. Sensorineural hearing loss which is the result of dysfunction of the conchlea, conchlear
nerve or central auditory pathway.
Hearing Loss in Puppies
We test litters of puppies who are prone to having hearing loss such as Dalmatians, English Setters, English Cockers, Australian Cattle dogs, Jack Russell Terrier, and other breeds. The best time to test is at seven weeks of age. Dogs can lose hearing up to 16 weeks of age, so retesting before breeding if we get a questionable reading on the first test or if the owner notices and problems, is not an uncommon practice.
If a puppy tests negative in one or both ears, usually nothing can be done to regain hearing if they suffer from cochlear degeneration. The ears are checked for any type of infection, which can interfere with the test, but congenital deafness cannot be restored. Chronic ear problems can cause thickening of the ear canals and cause poor signals to the brainstem, which would cause poor hearing and a questionable test. In this situation the patients will often be retested after being treated appropriately.
Most responsible breeders of dogs who are at high risk for congenital deafness will test liters of puppies before selling them.
A dog that seems to be able to hear but cannot locate where the sound is coming from may be affected by unilateral hearing loss (hearing in one ear only). A BAER test can confirm this and identify the affected ear.
Raising a deaf dog takes patience. Raising a deaf dog with a hearing dog is sometimes easier. Having a deaf dog around children can be risky. Deaf dogs seem to startle easier and may strike out at a child who comes too close or surprises him from behind. Deaf dogs must be supervised when outside; they tend to be hit by cars more often because they do not hear the sound of the street.
We recommend a book “Living with a Deaf Dog” by Susan Cope Becker. This book gives some training techniques to help an owner who takes on the task of a deaf dog.
Learn more about this disease by contacting our Neurology service at your nearest BluePearl veterinary hospital. Here are our hospital locations.
© BluePearl Veterinary Partners 2012