BEAR TESTING
What is BAER?
BAERCOM stands for Brainstemm Auditory Evoked Response (BAER), the main component of the BAERCOM system is the unit itself. This BAERCOM generates audible clicks that stimulate the acoustic nerve, that then gives you the BAER data response. The BAERCOM also incorporates EEG signal conditioning circuitry, BAER testing is most often used to screen dogs for congenital deafness. Numerous breeds are at the risk for this disorder and in the vast majority it is related to coat colour.
Why use BARECOM?
BAERCOM can help us to identify if a dog is deaf at a young age ( starting from age of six weeks), which then helps the breeder and new owner to prepare for the puppy's life. Deaf dogs can be hard to train and would need to be taught from a young age commands for the owner and canine to communicate. Without testing these breeds could cause more harm to future litters and the puppy itself, as the puppy could become startled easily or react differently if not trained around congenital deafness. As for future litters you would ideally avoid breeding from the puppy in the future to prevent any offspring carrying the trail. Congenital deafness is mostly recognized as a problem in dogs breeds that usually carry the piebald gene or white coats like:
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Dalmatians
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English Setters
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Border Collies
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Australian Shepherds
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White Boxers
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White Bull Terriers
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Australian cattle dogs
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Jack Russell terriers.
Pure cat breeds carrying the white (W) coat pigment gene and at risk for congenital deafness:
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White
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White Scottish Fold
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European White
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Foreign White
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Norwegian Forest Cats
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Ragdoll
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Siberian
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White Turkish Angora
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White American Wirehair
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White Cornish Rex
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White American Shorthair
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White Devon Rex
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White British Shorthair
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White Manx
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White Exotic Shorthair
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White Persian
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White Oriental Shorthair
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White Maine Coon
Canine Hearing abilities.
Puppies are functionally deaf at birth, their ear canals begin to open at two weeks old. Canines have 18 ear muscles in their ears, they use their ears muscles to raise and tilt their head to better catch sound waves. Sound waves are measured by two main characteristics, frequency and loudness, the frequency is measured by hertz Hz's which determines the pitch of sound. Loudness is by volume, or the intensity of the sound pressure, and it is measured in decibels db. Because canines have such a high range being approximately 40 Hz-60 000 Hz, noise and trauma is a concern for them, repeated exposures to that type of noise 85dB can create hearing loss in both humans and canine. Canines have tiny hair-like sensory cells, which are called cilia, deep in the ear canal and can be easily damaged by sound pressure.
BAER test results
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Affected – bilateral: the dog is completely deaf in both ears
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Affected – unilateral: the dog is completely deaf in one ear and able to hear normally in the other
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Unaffected: the dog has normal hearing in both ears
HOW IS A BAER HEARING TEST PERFORMED?
The BAER hearing test is completed by using a specialized computer that is connected to three electrodes placed just under the skin on the patient’s head. The placement of these small electrodes is not painful to the pet.
Once the BAER electrodes are in place, the patient will then have a soft foam earphone placed in each ear. These earphones make a clicking sound. After the sound has been transmitted, the electrodes will detect any activity in the hearing pathways of the cochlear nerve and brainstem
This activity will be transmitted to the computer and will show as waveforms on a graph, much like an electrocardiogram (EKG) shows electrical activity in the heart. Peaks in the waveform represent activity in the cochlea and other auditory pathways, while a flat waveform represents inactivity (deafness).
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Is sedation needed for a BAER test?
Most dogs do not require sedation for a BAER test. Many puppies actually fall asleep during the hearing test.
Causes of Deafness
Deafness can be either inherited or acquired. Hereditary deafness can be either cochleosaccular or neuroepithelial in origin. Cochleosaccular is the most common cause of deafness and is associated with coat colour patterns. It is usually seen in dogs with the piebald colour genes or merle colour gene. It can cause deafness in either one or both ears and is seen more in association with blue eyes and a white coat. This type of deafness can be first seen between 1 to 3 weeks of age.
Neuroepithelial deafness is not associated with coat patterns. It usually impacts both ears and is typically seen around the same age.
Acquired deafness can be caused by numerous factors. Some medications can be toxic to the ears. Generally, the deafness caused by these drugs is permanent, but some animals may regain hearing over time. Many older animals develop deafness. It typically starts with the loss of ability to hear mid-level to high-level frequencies and eventually leads to the inability to hear any frequency
WHY BAER Testing?
Many breeders of dogs that have hereditary deafness will choose to BAER test their breeding animals and puppies. If you suspect your dog is deaf, contact KMPservices to find out when BAER testing is available. BAER testing is the gold standard in deafness diagnosis. BAER stands for Brainstem Auditory Evoked Response; the test detects electrical activity in the cochlea and auditory pathways in the brain. It is performed by a veterinarian, who will place small electrodes on the dog’s head and then send a stimulus click through foam earpieces. Each ear is tested individually.
New study reveals deafness in Dalmatians declines
Thanks to careful breeding decisions
A new study has revealed a marked improvement in the number of deaf dogs born in one of the world’s most recognisable breeds.
The research, carried out as part of a collaboration between the Kennel Club and the Animal Health Trust, examined the number of cases of deafness in Dalmatian puppies, how common it is and how this has changed over time. The study, the largest of its kind, analysed 26 years’ worth of hearing test data from nearly 9,000 Kennel Club registered Dalmatians.
Dalmatians are known to have an increased risk of deafness compared to other breeds. This type of deafness is inherited, with the function of one or both ears sometimes being affected. From a young age (around five to six weeks), dogs can have their hearing checked using a BAER (Brainstem Auditory Evoked Response) test. Breeders can use the results of these tests to help them select unaffected breeding dogs and reduce the risk of producing puppies with hearing loss.
Researchers analysed BAER test result data, alongside pedigree information from the Kennel Club database, and showed that deafness is moderately heritable, meaning that a parents genes do, to some degree, influence a puppy’s risk of deafness. Further analysis revealed that 17.8 per cent of Dalmatians tested were affected by deafness (13.4 per cent in one ear and 4.4 per cent in both ears). During the 26 years of data that were looked at, the overall number of dogs with deafness fell by about a third - the number of dogs that were deaf in one ear decreased by over a quarter, while dogs with deafness in both ears decreased by a half.
The study further analysed physical descriptions of the dogs recorded during their BAER test, and confirmed findings from previous studies - that dogs with blue eyes are at increased risk of deafness, while those with a patch of colour on their head have a decreased risk of deafness. During the 26 years of study data, the number of dogs with blue eyes decreased, while those with a patch of colour on their head increased.
Dr Tom Lewis, Quantitative Geneticist and Genetics Research Manager at the Kennel Club said: “Our research shows that a Dalmatian’s genes can influence its puppies’ risk of deafness. We suspect that there are a number of genes and other factors interacting and influencing a dog’s risk of hearing loss, so reducing deafness in the breed is not as straightforward as it seems.
“Analysis shows that for decades, Dalmatian breeders have been actively reducing the incidence of hearing loss in the breed by carefully selecting dogs, not only based on their ability to hear, but also other traits known to influence this. The breed clubs and breeders have done an incredible job at reducing the prevalence of hearing loss and with data from our new study, we hope can help find ways to help make an even bigger impact on the health of the breed.”
Published on17 June 2020 at 11:12am
To read the study in full visit: http://dx.doi.org/10.1111/jvim.15776