Deafness often arises from severe cold, and may then be expected to disappear as the dog recovers, but it is sometimes congenital, and when such is the case, no remedies are of any avail. If it comes on after distemper, it will generally disappear, or if it occurs from ordinary cold. Whenever it is obstinately persistent for more than a fortnight, a seton in the neck is the best remedy, kept in for some weeks.

Canker of the ear is an eruption attacking the ear passage or external ear, as the case may be, rather than a disease of the ear itself. According to its seat, as above mentioned, it is termed external or internal, and then requires very different treatment. Internal canker may be suspected when the dog is seen to shake his head constantly without having any eruption on the external ear to account for this habit. On looking into the ear passage, it will generally be found to be full of yellow matter, but sometimes the membrane lining is thickened, red, and dry. In either case it is inflamed, and requires local as well as general treatment. A solution of nitrate of silver should be dropped into the passage every other day, alternating its use with the green iodide of mercury, which should be blown in without admixture with lard. The dog should be physicked with a mild aperient, his diet should be reduced in quantity and quality, and some boiled green vegetables should be added to it every other day.

These remedies generally effect a cure in a fortnight, unless the disease has extended beyond the drum of the ear into the delicate structures of the interior, in which case it is often incurable.

External Canker attacks the tips of the ears, producing a scabby sore, on one or both, which is greatly aggravated by the dog continually shaking his head. Hence it often requires a canvas cap to be tied on, so as to confine the ears, without which, in bad cases, no remedy is effectual. The general treatment is the same as for internal cankers, but the sores require touching with bluestone after rubbing off the scales, and afterwards applying the ointment of green iodide of mercury.

In very bad cases of either kind, when the system is in a very gross state, 6 or 8 drops of liquor arsenicalis should be added to the food twice a day, proportioning the dose to small dogs accordingly. It should be continued for weeks or even months, until it produces a redness of the white of the eye.