HEREDITARY DEAFNESS
Bull Terriers along will other breeds carry the deafness gene It can affect both coloured and white Bull Terriers. Dogs can be totally deaf (Bilateral
deafness )or can have hearing in one ear ( Unitaleral deafness)
Inside the dogs ear.
Their are four parts to a dogs ear, the ear flap, the ear canal , the middle ear and the inner ear. The ear flap is made of cartilage, muscle and skin which
you can see on the dogs head this flap captures sound waves and allows them to travel to the ear drum (tympana membrane) which than vibrates. The
middle ear is the area behind the ear drum which contains the tympana cavity. This is where the auditory tube, the tympana nerve, the vestibulal window
and the cochlea along with other parts are. Also within the middle ear are three small bones ( the smallest bone in the body) the malleus. The incus and
the stapes. These bones transmit the air vibrations from the ear drum and tympanic cavity to the inner ear. The inner ear is where the air vibations are
converted into nerve impulses, which when reaching the brain results in hearing. It is a labyrinth of fluid filled sacs, which are contained within an
osseous lebyrinth. The osseous parts of the inner ear are a shell shaped cochlea. This cochlea winds around a hollow core,containing the cochlea
nerve. Within the cochlea are around 10,000hair cells which respond to the air vibrations and stimulates the nerve cells to send messages to the brain,
these hair cells are what the ear uses to changes to electrical signals that the brain then recognises as sound.
What causes deafness
The cause of deafness is not yet fully understood, however it is believed to be caused by the loss of blood supply to the cochlea and thus causing the
degeneration of the hair cells contained in the cochlea. Without these hair cells their is no way the ear can change air vibrations into electrical signals
which the brain recognises as sound. Inheritance is not known at this time though DNA testing is being conducted to try and find the gene which
produces deafness, as two fully hearing parents can produce deaf or partial deaf puppies while in the same litter you can have full hearing puppies.
BAER testing
BAER (Brainstem Auditory Evoked Response) The only way to be certain that you dog can hear properly from both ears. In this test a computer is used
to record the electrical activity of the brains response to sound stimulation. A sound stimuli, a series of clicks, is passed though headphones placed over
the dogs ears whilst recording electrodes are placed on the dogs neck just behind the head. Puppies can be tested from 6 weeks of age and will require
a light sedation to keep them still. BAER testing is required only one in a puppies life and a certificate will show the results.
Bull Terriers along will other breeds carry the deafness gene It can affect both coloured and white Bull Terriers. Dogs can be totally deaf (Bilateral
deafness )or can have hearing in one ear ( Unitaleral deafness)
Inside the dogs ear.
Their are four parts to a dogs ear, the ear flap, the ear canal , the middle ear and the inner ear. The ear flap is made of cartilage, muscle and skin which
you can see on the dogs head this flap captures sound waves and allows them to travel to the ear drum (tympana membrane) which than vibrates. The
middle ear is the area behind the ear drum which contains the tympana cavity. This is where the auditory tube, the tympana nerve, the vestibulal window
and the cochlea along with other parts are. Also within the middle ear are three small bones ( the smallest bone in the body) the malleus. The incus and
the stapes. These bones transmit the air vibrations from the ear drum and tympanic cavity to the inner ear. The inner ear is where the air vibations are
converted into nerve impulses, which when reaching the brain results in hearing. It is a labyrinth of fluid filled sacs, which are contained within an
osseous lebyrinth. The osseous parts of the inner ear are a shell shaped cochlea. This cochlea winds around a hollow core,containing the cochlea
nerve. Within the cochlea are around 10,000hair cells which respond to the air vibrations and stimulates the nerve cells to send messages to the brain,
these hair cells are what the ear uses to changes to electrical signals that the brain then recognises as sound.
What causes deafness
The cause of deafness is not yet fully understood, however it is believed to be caused by the loss of blood supply to the cochlea and thus causing the
degeneration of the hair cells contained in the cochlea. Without these hair cells their is no way the ear can change air vibrations into electrical signals
which the brain recognises as sound. Inheritance is not known at this time though DNA testing is being conducted to try and find the gene which
produces deafness, as two fully hearing parents can produce deaf or partial deaf puppies while in the same litter you can have full hearing puppies.
BAER testing
BAER (Brainstem Auditory Evoked Response) The only way to be certain that you dog can hear properly from both ears. In this test a computer is used
to record the electrical activity of the brains response to sound stimulation. A sound stimuli, a series of clicks, is passed though headphones placed over
the dogs ears whilst recording electrodes are placed on the dogs neck just behind the head. Puppies can be tested from 6 weeks of age and will require
a light sedation to keep them still. BAER testing is required only one in a puppies life and a certificate will show the results.
| Heart |
| Patella |
| Kidney |
| A Graph showing BAER testing of a 6 week old puppy |
| The BAER testing computer |
| A Denotany puppy being BAER tested |
| Back to Hereditary |
