Ear infections in dogs

Vet’s Voice

INFECTION of the external ear canal is called otitis externa (outer ear infection) and is one of the most common types of infections seen in dogs.

Some breeds, particularly those with large, floppy or hairy ears like cocker spaniels, miniature poodles or Old English sheepdogs, appear to be more prone to ear infections, but ear infections may occur in any breed.

Ear infections are painful and may cause head tilting. Many dogs will shake their head and scratch their ears trying to relieve the discomfort. The ears often become red and inflamed and develop an offensive odour. A black or yellowish discharge commonly occurs. In chronic cases the ears may appear crusty or thickened and the ear canals often become narrowed (stenotic) due to the chronic inflammation.

Ear mites can be the primary cause of several of these symptoms, including a black discharge, scratching, and head shaking. However, ear mite infections are more common in puppies and kittens. Adult dogs may occasionally contract ear mites from puppies or cats that are infected. Ear mites create an environment within the ear canal that often leads to a secondary bacterial or yeast (fungal) infection.

There are several kinds of bacteria and at least one type of yeast (fungus) that commonly cause ear infections. Without knowing the specific kind of infection present, veterinarians are not in a position to know which medication to use. In some cases, the primary problem is a foreign body, a polyp, skin allergy or a tumour.

Treatment with ear medication alone will not resolve these problems. Secondary factors such as high humidity and ambient temperatures, and swimming exacerbate ear infections. Head shaking and ear scratching can also result in the development of othaematomas. An othaematoma is a blood clot that forms in the external ear between the ear cartilage and the skin as a result of rupture of blood vessels in the ear due to trauma from head shaking and ear scratching. It appears as a soft bubble on the external ear.

It is important that your dog be examined to identify primary problems and to ensure that the eardrum is intact. Administration of certain medications can result in loss of hearing if the eardrum is ruptured. This can only be detected by a thorough ear examination by your veterinarian. Nearly all ear infections that are properly diagnosed and treated can be successfully managed. However, if an underlying cause remains unidentified and untreated, the outcome will be less favourable. Several recheck examinations may be needed before the outcome is successful.

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