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Cats and their sensitive hearing
Cats can be affected by hearing loss too – but some can be helped with cochlear implants.
A cat’s hearing – just like its human owner’s – will often deteriorate with age. As time wears on, the blood supply to the fine tissue structures in the ears is compromised and hearing ability is impaired. Those around them should be considerate of this new situation – cats with no hearing are easily startled, for example, so people should make themselves clearly visible as they approach them. Vibrations caused by a firm footfall, or a waft of air from a hand-clap, will also help. Life outdoors may become difficult for cats, however – when they are no longer able to hear defensive or threatening noises from their fellow felines, for instance.
Cats can also lose their hearing through disease. Infections caused by mites, fungus or bacteria can diminish their ability to hear, as can tumors or polyps in the ear canal. If an animal is suddenly unable to hear, it will become confused and unsettled, and may react with agitation and/or aggression. It will seek closer contact with its owners or may even withdraw into itself completely, and such signals should not be ignored; treating cats at the right time can prevent lasting damage.
A vet can help if there is an infection, but what happens if a cat is born deaf? And this is not as uncommon as one might think, especially among white cats with blue eyes: such animals are deaf in one or both ears from birth as a result of leucism, a genetic mutation whereby cats lack melanocytes, the cells responsible (amongst other things) for skin colour and eye pigmentation. Their coat is thus not actually white, but colourless (the skin underneath is pink) and their eyes seem blue as the iris has no colour at all. Most importantly, however, melanocytes are also crucial to development of hearing in the inner ear; if a cat has too few of these cells, or they are missing entirely, it will be able to hear only imperfectly or not at all.
Congenital hearing loss can lead to the growth of abnormal synaptic structures in the auditory nerves of both cats and humans. “Fitting a cochlear implant can compensate for such damage in humans,” says Stefan Launer, Sonova’s resident expert in audiological research and Senior Vice President Science & Technology. “They provide artificial stimulation for the auditory nerves and thereby normalise synaptic function.”
This led researchers at Johns Hopkins University to wonder whether cochlear implants might be able to help cats with congenital hearing loss as well, and they proceeded to fit young kittens with the devices in 2005; and sure enough, after three months the synapses in their auditory nerves had normalised.
“Fitting cats with such implants has so far been the exception rather than the rule, but the devices have been used for humans with great success for many years,” explains Launer.
Find out more about cochlear implants manufactured by Sonova brand Advanced Bionics.