Bull Terriers along with many other breeds suffer with deafness, it is associated more with white dogs however coloured and even solid Bull Terriers can be affected. Dogs can either have hearing loss in one ear (partial deafness) known as unilateral deafness (or unis) or have hearing loss in both ears (totally deaf) known as bilateral deafness.

Deafness in the Bull Terrier is widely excepted by breeders and although it does state in the Bull Terrier Clubs code of conduct that deaf puppies should not be sold, testing for deafness is not endorsed.

Since the BAER test (more details below) has become more widely available more and more breeders are testing their breeding dogs and puppies, whilst this will not completely rid the bred of this condition it will help reduce the number of Bull terriers with hearing loss.

 

Inside the dogs ear and how they hear

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 captures sound waves and allows them to travel through the ear canal to the ear drum (tympanic membrane) which then vibrates.

The middle ear is the area behind the ear drum which contains the tympanic cavity. This is where the auditory tube, the the tympanic nerve, the vestibular window and the cochlea along with other parts are. Also within the middle ear are three small bones (the smallest bones 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 vibrations are converted into nerve impulses, which when reaching the brain result in hearing. It is a labyrinth of fluid filed sacs, which are contained within an osseous labyrinth. 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 10,000 hair 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 change air vibrations to electrical signals that the brain then recognises as sound.

What causes Deafness and how is it inherited?

The cause of deafness is not yet fully understood, however it is believed to be caused by the loss 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, thus causing deafness.

The cause of the loss of blood supply is also unknown but is thought to be due to the absence of pigment producing cells in the blood vessels.

Again the mode of inheritance is not yet understood as two dogs with full hearing can still produce partial or fully deaf puppies. It is known however that by breeding a partially deaf or deaf bull terrier will increase the likeliness of deaf puppies, therefore it is advised not to breed from partial/fully deaf bull terriers.

 

The BAER test explained

The BAER (Brainstem Auditory Evoked Response) is the only way to certain that your dog can hear properly from both ears. In this test a computer is used to record the electrical activity of the brain's response to sound. stimulation. A sound stimuli, normally clicks, is passed through headphones placed over the dogs ears whilst recording electrodes are placed on the dogs heads.

Please click on the picture below of a Bull Terrier puppy having a BAER test carried out.

    

        

Pictures kind permission of Icacia

Bull Terriers can be BAER tested from 5 weeks old until any age. This is a non invasive nor painful procedure so small puppies will not require sedation however an adult who won't sit still may require a light sedation. BAER testing is only required once in a Bull Terriers life and they will be certified either with normal hearing, unilateral deaf (deaf in one ear) or bilateral deaf (deaf in both ears).

You will be given a certificate to show the dog has had a BAER test which should be kept to show potential puppy buyers.

Please click the link below to see a copy of a BAER test certificate, unfortunately this is only a photo while we await a scanned copy of the certificate but should give you some idea of what a breeder should produce.

Link to BAER Test Certificate

 

Further information also on further tests to determine the amount of hearing a dog has.

This link gives more information on BAER & more - http://www.dermapet.com/articles/hearing.html

 

Deaf Bull Terriers

Bull Terriers who are deaf in just one ear do not normally act in any different way to hearing bullies.

Bull Terriers who are completely deaf tend to learn as puppies to pick up other signals to recognise what is going on such as air/ground vibrations when a human enters the room etc, therefore do respond in similar ways to a hearing dog. Deaf bullies respond extremely well to training using hand signals, usually quicker than hearing dogs as they have no noise to distract them! Puppies should attend normal puppy training classes to socialise in the same way a hearing dog would.

The only extra training a deaf puppy requires is in being startled, this should be done slowly whilst a puppy so they do not become scared if woken by accident when sleeping.

Some people believe that deaf Bull Terrier puppies WILL become aggressive, I would like to note that their is NO medical research to back this up. I personally believe their is just as much chance of a hearing dog becoming aggressive as their is a chance a deaf dog becoming aggressive. 

Please follow the links for information on training using hand signals.

http://www.deafdogs.org/

http://pets.groups.yahoo.com/group/deafdogs/

 

Author Debbie Wiles

 

 

NOTE: INFORMATION SUPPLIED ON THIS PAGE IS FOR INFORMATION PURPOSES ONLY. IF YOU SUSPECT YOUR DOG HAS ANY OF THE ABOVE SYMPTOMS OR PROBLEMS PLEASE SEEK THE ADVICE OF YOUR VET.