BAER Testing Protocol
The Brainstem Auditory Evoked Response (BAER) test is the only proper method of diagnosis.
Bilateral hearing passes the test. Unilateral or bilateral deafness fails.
Examination protocol
First the ear canal and the eardrum being thoroughly inspected with an otoscope to rule out that any deafness is caused by a very dirty and / or inflamed ear canal or a broken eardrum.
Then, using special equipment nervous hearing tested, called Brainstem Auditory Evoked Response Research (BAERtesting). To prevent interference with the equipment by masticator muscles to exclude the animal gets to study a small ruffle. Under sedation, 3 needle electrodes placed in the dog: one in each ear base and a ground electrode in the middle of the head. Also, an
earpiece where the sound stimulus is passed into the external auditory canal applied. In the middle are the sensory cells that convert sound into electrical potentials. These electrical potentials are measured during the BEAR test.
During the BEAR-test, the average brain activity is visible on the screen. The dog gets through an earpiece (unilateral) click noises (1000 sound stimuli with a frequency of 11 clicks per second with a strength of 70 DECIBELL). The first two peaks represent the pulses by the cochlea, the auditory nerve and can be produced, and the next, smaller peaks are due to the
higher centers in the brains formed.
Deafness is often associated with the Leopard/merle gene, which produces a Leopard or patchwork with combination of white with dark and light areas and often double glass eyes. Even dogs without Leopard look can be carrier of this gene. A solid looking Catahoula, red, red& brindle, Grey, grey& tan, Black, Black& brindle or black& tan, born out two Leopard looking
dogs, can carry the Merle gene. This is called Cryptic Merle, Mcm. The Merle gene (M) is dominant so that affected dogs (Mm or Mcm) can be deaf. However, when two dogs with Merle gene are bred, 25% will end up with the MM genotype. These dogs often have a solid white coat with patches and blue irises, are often deaf and/or blind, and can be sterile. So it is a higher risk to breed two Merle looking dogs. Breeders of these dogs know it is a risk to breed Merle to Merle.
In this case the deafness is neither dominant nor recessive, but is linked to a dominant gene that disrupts pigmentation and secondarily produces deaf dogs.
Unilaterally deaf dogs cannot be detected by other means, and these dogs will pass on their deafness genes. So for us it is
important to test all pups/ dogs who are a suspicious.
Because a Catahoula can carry a MM, double merle gene, which sometimes is not show on the outside, it is better to avoid breeding Merle looking x Merle looking. Below you see different an example a of unilateral and bilateral dog.
Bilateral hearing passes the test. Unilateral or bilateral deafness fails.
Examination protocol
First the ear canal and the eardrum being thoroughly inspected with an otoscope to rule out that any deafness is caused by a very dirty and / or inflamed ear canal or a broken eardrum.
Then, using special equipment nervous hearing tested, called Brainstem Auditory Evoked Response Research (BAERtesting). To prevent interference with the equipment by masticator muscles to exclude the animal gets to study a small ruffle. Under sedation, 3 needle electrodes placed in the dog: one in each ear base and a ground electrode in the middle of the head. Also, an
earpiece where the sound stimulus is passed into the external auditory canal applied. In the middle are the sensory cells that convert sound into electrical potentials. These electrical potentials are measured during the BEAR test.
During the BEAR-test, the average brain activity is visible on the screen. The dog gets through an earpiece (unilateral) click noises (1000 sound stimuli with a frequency of 11 clicks per second with a strength of 70 DECIBELL). The first two peaks represent the pulses by the cochlea, the auditory nerve and can be produced, and the next, smaller peaks are due to the
higher centers in the brains formed.
Deafness is often associated with the Leopard/merle gene, which produces a Leopard or patchwork with combination of white with dark and light areas and often double glass eyes. Even dogs without Leopard look can be carrier of this gene. A solid looking Catahoula, red, red& brindle, Grey, grey& tan, Black, Black& brindle or black& tan, born out two Leopard looking
dogs, can carry the Merle gene. This is called Cryptic Merle, Mcm. The Merle gene (M) is dominant so that affected dogs (Mm or Mcm) can be deaf. However, when two dogs with Merle gene are bred, 25% will end up with the MM genotype. These dogs often have a solid white coat with patches and blue irises, are often deaf and/or blind, and can be sterile. So it is a higher risk to breed two Merle looking dogs. Breeders of these dogs know it is a risk to breed Merle to Merle.
In this case the deafness is neither dominant nor recessive, but is linked to a dominant gene that disrupts pigmentation and secondarily produces deaf dogs.
Unilaterally deaf dogs cannot be detected by other means, and these dogs will pass on their deafness genes. So for us it is
important to test all pups/ dogs who are a suspicious.
Because a Catahoula can carry a MM, double merle gene, which sometimes is not show on the outside, it is better to avoid breeding Merle looking x Merle looking. Below you see different an example a of unilateral and bilateral dog.
Being BAER tested with sedation.
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Checking the ears if they are clean.
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Hearing, when deaf it would be a staight line.
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Getting sleepy!
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Slowly waking up after the test.
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Sunnydog's Dakota. Unilateral deaf Catahoula
Excessive White with Red Leopard patches Catahoula. Tested Bilateral deaf. Brahmina Dogo Dogino- Pelle. Owner: S. Birkner
