Apparent loss of hearing is commonly seen in old dogs, but rarely reported in old cats. Owners notice that their pet is slow to respond to auditory stimuli such as the noise of them being called, whistles, the sound of the owner entering the room, or loud bangs such as doors slamming or fireworks. Sometimes owners can recognise complete deafness when their dog fails to respond to all auditory stimulation but does respond immediately to visual recognition.

Chronic inflammation can lead to thickening and pigmentation of the skin lining the ear canal and this may lead to narrowing of the external auditory meatus. This in itself may not cause a significant impairment in hearing.