Dogs are expert at reading us, and our behaviour. They can predict our actions from imperceptible signals. Seizure alert and diabetes alert dogs use these skills to protect their owners. This sensitivity makes it difficult to notice when their senses are compromised. A deaf dog may greet you enthusiastically, having ‘heard’ your footsteps through floor vibrations. So, hearing and vision loss can be advanced before we observe changes in behaviour. We may think our dog has selective hearing or is being naughty.
Could my dog be deaf?
Deafness can affect dogs of any age, gender and breed.
Puppies can be born deaf. This is called congenital deafness. It is often seen in dogs with white or merle colouration. Dalmations, Australian Cattle Dogs and English Setters carry a gene called the piebald gene which predisposes them to congenital deafness (1). The disease is inherited so if you are buying a pup from a susceptible breed, check the parents have been tested. Congenital deafness is permanent.
Some causes of deafness can affect middle-aged dogs but hearing loss is most common in old age.
What are the signs of deafness?
Loss of recall is often the first sign of hearing loss. An obedient dog will no longer come when called.
Where your return home was marked by an excited dog greeting you at the door, they may no longer hear your car or key in the door. Many dogs go into a frenzy when the doorbell rings or the food bowl comes out. This behaviour stops. A favourite squeaky toy may become less appealing when they can’t hear the squeak.
All dogs have a startle response when they are surprised. You may notice the startle response occurring more often or being more exaggerated if a dog is deaf. For example, if your dog is resting and doesn’t hear you approach, they may jump when you stroke them.
Deaf dogs may bark or whine excessively. Dogs may become isolated by hearing loss, sleeping more and interacting less. They may become fearful, anxious, confused or even aggressive.
Deafness may be partial or complete. It can affect both ears or one ear. Some dogs with partial or unilateral hearing loss may be unable to work out where sound is coming from and tilt their head.
If infection or inflammation is causing hearing loss, ears may be painful to touch. The dog may be scratching at their ears. There can also be an unpleasant odour, excess wax and discharge from the ear.
What causes hearing loss?
Sound waves enter the ear canal (outer ear), travel through eardrum into the middle ear and on into the inner ear. The vibrations are translated into nerve impulses, which are then carried to the brain. Any of these areas can be diseased and cause deafness.
Ear infections can affect all parts of the ear.
Discharge and swelling can obstruct the outer ear. If the infection broaches the eardrum, infection spreads to the middle and inner ear. Dogs who swim regularly and those with allergies or narrow ear canals are more susceptible to infection. Untreated ear infections are painful and debilitating and can cause severe illness and aggression.
The outer ear can also be blocked by a build-up of wax. Dogs with a lot of ear hair can experience hearing loss as the hairs become clogged with debris.
Ear canals can also be blocked by foreign bodies.
Grass seeds are the most common culprit. If you can remove the grass seed at home, the eardrum should still be checked for perforation.
Deafness caused by infection and ear canal obstruction is usually temporary and resolves with treatment.
Topical medicines may be safe in the outer ear but damage the inner ear if they cross the eardrum. This is the reason that a vet will always check the eardrum with an otoscope before prescribing ear medication. Antibiotics, such as neomycin and gentamicin can be ototoxic, as well as other ingredients in ear drops. The damage to the inner ear may be temporary or permanent.
Injury to the brain, structures of the ear or the auditory nerve can result in hearing loss. This is rare but may occur with head trauma.
Congenital deafness in puppies is usually diagnosed after 6 weeks of age. The inner ear does not transmit vibrations to the brain. Deaf puppies behave differently to their littermates, miss audible cues, may appear isolated and can be very loud.
Old dogs often suffer progressive acquired hearing loss as the receptors in the inner ear fail. This is similar to hearing loss in older people.
How is deafness diagnosed?
Deafness can be confirmed by a Brainstem Auditory Evoked Response (BAER) test. This is a non-invasive test which measures brain activity in response to sound. However, this is an expensive test, and most deafness is evident with home testing.
To assess your dog’s hearing: clap, shout, ring the doorbell or open a food wrapper behind your dog so they cannot see you. You should not be close to your dog in case air vibrations signal the noise. The noise should be unexpected. If you do not see a response try calling in a louder voice, with varying pitch. Dogs may lose high frequency (high pitched) sound first.
What can be done?
If you suspect that your dog has hearing loss, visit your vet. The outer ear canal can be examined with an otoscope. Your dog may need sedation or anaesthesia and ear flushing to diagnose and treat the problem. If inner ear infection is suspected, then a CT scan may be recommended.
In many cases the cause of deafness is not reversible. Dogs with hearing loss may need to be walked on the lead or in safe places. They will not hear you call them if they are in danger because of traffic, water, aggressive dogs or other hazards. Make sure that your current phone number is on their collar in case they do become lost. Collars or coats with ‘I am deaf’ written on them can ensure anyone who finds your dog is sympathetic and careful.
Dogs can be retrained using hand signals. A vibrating collar can encourage them to look at you for the hand signal if they are off lead.
If you are regularly losing your dog in the house or garden attaching a bell to their collar can help.
Deaf dogs can live a happy, fulfilled life. Most learn hand signals quickly. With recent or progressive hearing loss they can become confused and anxious and need reassurance. Regularly checking your dog’s ears can also prevent deafness caused by infection, inflammation and obstruction. Be extra vigilant with susceptible breeds and old dogs.
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