Deafness may be " complete " or only" partial," and confined to one, or affecting both ears.

In some dogs it is congenital, i.e., present from birth; in others acquired.

Severe canker will cause deafness, so will a blow over the ear.

Morbid growths in the passage, and accumulation of waxy material, etc., will likewise produce " partial " or " complete " loss of hearing.

Treatment must be directed to the removal—whenever possible—of the cause.