Yes, almost certainly the external ear canal of one or both of his ears is severely inflamed, a condition known as otitis externa but popularly referred to as 'canker'. (Incidentally, canker has nothing to do with cancer, despite the similarity of spelling.) A number of factors can contribute to this extremely common affliction.

It is normal for wax to be produced by glands in the skin lining the ear canal, and to stop an excessive build-up it is usual for the wax to dry out and be shed from the ear as flakes from time to time. However, the shape and structure of the ear in some breeds prevents efficient wax removal. The pendulous ears of the Cocker Spaniel and Bassett Hound severely restrict ventilation of the canal, and the narrow ear canal of the Miniature Poodle is easily blocked. In some breeds, such as the German Shepherd Dog and the Dachshund, too much wax is produced. Once the ear canal has been impacted with wax, and this is more likely if there is a lot of hair present, inflammation will commence. Bacteria and yeasts (fungal organisms), which are normally present in a passive role, are now provided with suitable moist conditions in which to multiply and they intensify the inflammation.

Ear mites (Otodectes cynotis), which are the most common cause of ear problems in cats, are less often the initiating factor in dogs. Nevertheless whenever they are present they invariably result in considerable head shaking and ear scratching. Ear mites do not penetrate the skin but live and breed on the surface, grazing on the dead skin cells and possibly sucking lymph from the skin vessels. They are so small that with the eye alone they can hardly be distinguished inside the ear canal. However, with a magnifying glass they can be seen as small, whitish specks moving slowly over the lining of the canal. Veterinarians usually use a combined magnifying glass and light source, an auriscope or otoscope, to view the ear. When some of the wax from the ear is placed under a microscope the mites can be easily identified.

At times foreign bodies in the canal (such as pieces of twig or grit, or grass seeds) are responsible for irritation; even the presence of soap or water can promote inflammation. On other occasions an allergic reaction or, rarely, obstruction of the canal by a tumour, is responsible. However, once the condition is established, the secondary bacterial infection and self-inflicted damage produced by head-shaking, scratching and rubbing, create a vicious circle which may have a number of unpleasant sequels:

1. Violent shaking of the head can lead to the ear flaps being struck on nearby objects, resulting in rupture of the blood vessels and the formation of a swelling in the flap (haematoma) due to an accumulation of the blood that leaks out under the skin. This needs to be drained surgically, otherwise the flap will distort into a 'cauliflower ear' in healing.

2. The ear drum, a thin sheet of tissue stretching across the bottom of the ear canal, may perforate, allowing infection to spread to the middle ear and even on rare occasions to the inner ear. Though it seldom produces deafness this can disturb the dog's balance so that it falls over when attempting to walk.

3. In long-standing cases the skin lining the canal becomes thickened and ulcerated, i.e. chronic inflammation supervenes.

To identify and treat the cause the dog is best examined by your veterinary surgeon and, because of the pain this produces, tranquillization or general anaesthesia may be required. Treatment involves thorough cleaning and flushing out of the ear canal, removal of any foreign bodies and the application of appropriate medication - usually in the form of ear drops applied frequently for several days. Usually such drops contain a combination of some of the following: corticosteroids to reduce inflammation, ceruminolytics to dissolve the wax, antibacterial and antifungal drugs, local anaesthetics to relieve the pain, and parasiticides to kill any ear mites. Where mites are involved both ears should be treated even if one appears unaffected, and, because mites are readily transmitted between animals, all the dogs and cats in the household should be treated simultaneously, whether they are showing signs yet or not. Mites can also travel to other parts of the body and so it is a good idea to treat the whole body with a parasiticidal spray or powder.

In chronic cases surgery is necessary to open up the canal to permit adequate ventilation, drainage and the removal of diseased tissue.