Otitis extema is defined as an acute or chronic inflammation of the epithelium of the external ear canal, which may also involve the pinna. The reported incidences range from 5 to 20 percent in the dog and 2.0 to 6.6 percent in the cat. All breeds,ages, and sexes are represented. Miniature Poodles, Cocker Spaniels, Fox Terriers, Kerry Blue Terriers, Labrador Retrievers, and breeds with abundant hair growth in the ear canal have been reported to be at greater risk. Himalayan and Persian cats may also be over-represented. Predisposing factors facilitate the inflammation by permitting the external ear canal microenvironment to be altered allowing pathogenic or opportunistic bacteria to become established. The conformation of the ear canal may predispose an animal to otitis externa. Small, stenotic ear canals, seen in breeds such as the Chinese Shar-Pei, allow otic secretions to build up in the external ear canal and inhibit proper cleaning of the ear. The excess secretions provide a medium for growth of pathogenic bacteria. Hair removal should be performed in dogs prone to otitis externa; however, routine hair removal in dogs lacking ear disease is not recommended. Long, pendulous puma may restrict free airflow within the ear canal. Dog breeds with pendulous ears were shown to be at higher risk for developing otitis externa. Although breeds with pendulous pinna may be over-represented in the breeds presented with otitis externa, not all breeds with pendulous pinna are affected and some breeds with erect ears (German Shepherd dog) appear to be prone to otitis externa.
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