This is a rather indefinite term, as applied to the diseased ear of a dog; in fact, any malignant corroding sore may be called a canker, no matter where situated. Some writers describe, under the head of canker, a violent chronic otitis, attended by a purulent sanguinoid discharge. Others understand by canker a species of erysipelatous inflammation, that makes its appearance on the inside of the flap, and extends itself to the interior of the ear. What we understand by canker, is an acute inflammation of the lining membrane of the ear, destroying the tympanum or drum, and producing total deafness. The secretion is often considerable, and if not removed, will soon fill up the cavity of the ear with a dark reddish deposit, which greatly increases the irritation and inflammation of the parts. Mr. Blaine states that he has seen this disease take a very malignant character, and extend its ravages over the face, destroying the soft parts, and even penetrating through the bone into the interior of the head. 'Causes'.--This disease may he excited by any of those causes that produce a general or local inflammatory action; exposure to cold, the presence of malignant diseases on other portions of the body, high living, heat, confinement, or extraneous substances lodged in the organ itself. Water-dogs are most subject to this affection, owing, no doubt, to the frequent afflux of blood to these parts, while the remainder of the body is immersed in the water. A tendency to this peculiar inflammation may also be produced in these animals by the action of the water upon the delicate membranes of the ear, which occasions a violent shaking of the head and beating of the flaps, which not unfrequently bruises them considerably. Dogs that seldom or never go into the water are not, however, by any means exempt from the disease; as we have often seen it developed in terriers, mastiffs, and every species of mongrel. 'Treatment'.--When the disease appears in its acute form, and without any apparent cause beyond luxurious living and confinement, bleeding, purging, low diet, and regular exercise, together with tepid and soothing washes, will generally relieve the inflammatory action of the parts. The ear should be carefully and tenderly washed out with castile soap, and a small quantity of the following solution poured into it two or three times daily, and the ear worked about gently in the hand to secure the percolation of the fluid through its structure. [Symbol: Rx] Goulard's extract [Symbol: ounce] sj. Water 1 pint. Mix. or, [Symbol: Rx] Sugar of lead [Symbol: scruple] i. Water [Symbol: ounce] i. Mix. or, [Symbol: Rx] Powdered alum [Symbol: scruple] i. Water [Symbol: ounce] i. Mix.