The University of Pretoria’s Onderstepoort Veterinary Academic Hospital (OVAH) in the Faculty of Veterinary Science has invested in the latest device to test deafness in dogs and is currently testing 20–30 dogs per month, most of which are puppies.
“It’s important for dog breeders and people getting a puppy to make sure that there is no congenital deafness in the line, particularly in breeds that are more susceptible to it,” says OVAH’s Dr Paolo Pazzi. “Other reasons for testing include owners who are concerned that the dog they have adopted is deaf, or if their elderly dog has become deaf.”
Congenital deafness means that a dog is born deaf; it cannot be cured and there are no implants or operations available in veterinary science to enable dogs to hear.
“If, however, the deafness is related to otitis externa (inflammation of the external ear canal, also called “swimmer’s ear” in humans), the deafness should resolve, if treated early enough and appropriately,” Dr Pazzi explains.
Fortunately, Dr Pazzi says that there is a reliable way to test for deafness, called a Brainstem Auditory Evoked Response (BAER) test. The new device being used at OVAH to do this test is the American-manufactured UFI BAERCOM™, which quickly and painlessly assesses the dog’s level of hearing or deafness.
A sedated adult dog undergoing deafness testing at the Onderstepoort Veterinary Academic Hospital in UP’s Faculty of Veterinary Science.
“We had an older, larger, more clumsy device prior to this one as we have been doing deafness testing for some time, but it had become unreliable to the point that we could not do any BAER tests for about two years,” says Dr Pazzi.
The BAER test detects electrical activity in the cochlea and auditory pathways in the brain in much the same way that an antenna detects TV signals. The test is painless and the pup or dog is usually lightly sedated as movement interferes with the results.
Small electrodes are positioned on the animal’s head and connected to the device which reads and interprets the brain’s response to a specific clicking noise generated by it. Each ear is tested individually as the dog may only be deaf in one ear. If they can hear in the ear, the machine’s screen will show a recording of ‘waves’ of varying sizes and depths, but if they are deaf then the screen shows a recording of almost flat lines. Once both ears have been tested, the sedation is reversed, and a copy of the results are shared with the owner.
“Deafness in the dog – and cat – population is low overall, but responsible breeders of predisposed breeds should ensure their puppies can hear and that deafness is not carried in their breeding lines,” says Dr Pazzi.
Congenital deafness has been described in over 80 breeds, but is most commonly diagnosed in Dalmatians, Bull Terriers, Australian Cattle Dogs, English Setters, English Cocker Spaniels and Boston Terriers. There is an association between deafness and pigmentation with white dogs being predisposed and even more so if they are white with blue eyes.
Dogs with congenital deafness can be trained just like a hearing dog (using hand signals instead of speaking) and there are trainers who can assist with this. Many deaf dogs cope very well with hand signals.
If you are concerned about a pup, litter or adult dog and would like to test for deafness, you are welcome to contact the Onderstepoort Veterinary Academic Hospital (OVAH) Small Animal Medicine clinic on 012 529 8302 or email [email protected] for more information.