This page sets out the causes of hearing loss in cats. In the second half of the page I make a note about deafness due to developmental defects. Some cat owners may not be initially aware that their cat is deaf or deaf in one ear and believe that their cat has gone deaf when in fact it has been present since birth.
Testing For Deafness
This is more or less common sense. Most cats who have a close relationship with their human caretaker will usually respond (ear movement, meow or head turn) to their owner’s voice or when making a noise when the cat’s head is turned away. If there is no reaction on several tests it may indicate partial deafness of deafness. A cat caretaker who knows her cat well will see behavioural changes even though cats adapt well. Cats have superb hearing and are sensitive to sounds. They react to sounds albeit sometimes subtly. A good caretaker will see the differences. Unsure? See a veterinarian.
Cats can be tested scientifically for deafness using the BAER test. Cats are usually sedated. The test can be done at some vet referral centers and veterinary colleges.
Loss of hearing can be caused by:
- Old age, in the same way people lose hearing in old age
- Middle ear infections
- Injury to the head
- Ear canal blockage
- Inflammation of middle and/or inner ear
- Nerve damage
Elderly cats who have lost some hearing often retain their ability to hear very high pitched sounds which we can’t hear. There appears to be no device that can replicate the sound of a mouse (high pitched sound) which is guaranteed to be safe for cats. If there was it might be a useful way to communicate with a geriatric cat who had hearing loss.
Cats compensate for deafness but an owner should ensure he/she is safe. A cat with poor hearing shouldn’t be left alone to wander outside as it may be particularly unsafe due to road traffic as he won’t be able to hear traffic or other hazards e.g. predators (but see picture). However, supervised sessions outside should be OK or an outside enclosure. ASPCA recommends a bell on a collar so he can be located. Deaf cats should be able to feel vibrations, which may be a way of attracting attention. Deaf cats are liable to be startled so an approaching from a position where he can see the person would seem to be advisable.
Middle Ear Infections
The middle ear is the part beyond the ear drum which is at the base of the ear canal.
Otitis Media – not common.
- external ear infection travels to inner ear via ruptured ear drum
- tonsillitis, mouth infection, sinus infection travelling to inner ear via eustachian tube
- pain results in cat tilting head on the affected side.
- crouching low
- head kept still
- balance is affected
Injury to Head
This section does not require a discussion. If your cat has a head injury a vet visit is obligatory and if deafness follows you’ll know why.
Ear Canal Blockage
The canal is the part that leads to the eardrum. A blockage may be caused by:
- foreign body
- ticks (search result on PoC)
- ear mites (ear mite arts on PoC)
- ear polyps – these may start in the middle ear and grow out from there.
- wax gland cysts can cluster and block the war canal.
- wax gland tumor
Inflammation of the outer and middle ear narrowing the ear canal and preventing sounds waves impacting the ear drum.
Antibiotics such as streptomycin, gentamicin, neomycin and kanamycin can cause deafness when used for long periods by damaging the auditory nerve. Aminoglycoside group of antibiotics and anesthetics. Antiseptics. Chemotherapy drugs. Drugs to remove wax build up in the ear canal.
Heavy metals such as lead, arsenic and mercury can cause deafness through nerve damage (I believe).
Lead is found in paint, batteries, insecticides, fishing weights, plumbing materials and linoleum.
Arsenic can be found in herbicides (to kill weeds), insecticides, wood preservatives. Grass eaten by a cat that is regularly treated with a herbicide will lead to arsenic poisoning potentially.
Mercury poisoning could occur if a cat’s main diet is tuna. Mercury is found in batteries, latex paints, light bulbs and thermometers.
Some cats are born deaf in both or one ear due to a developmental defect.
It is common knowledge that some white cats are born deaf (see percentage). These are often white cats with blue eyes. Longhaired blue eyed cats are a higher risk of deafness than shorthaired blue eyed cats. White cats and blue eyed cats have a higher risk of deafness than normal.
Purebred cats with the white coat pigment gene are:
- American Shorthair
- American Wirehair
- British Shorthair
- Cornish Rex
- Devon Rex
- Exotic Shorthair
- Maine Coon
- Norwegian Forest Cat
- Oriental Shorthair
- Scottish Fold
- Turkish Angora
George Strain PhD, at Louisiana State University, USA, is an expert of deafness in cats and dogs.
- Cat Owners Home Veterinary Handbook 3rd edition.