EXTERNAL CANKER. 
109 
inflamed. In pigs the inflammation soon extends to the inner ear and 
brain, as shown by somnolence, loss of appetite, and burrowing in the 
straw, where the animal seeks to hide itself. Pigs not infrequently 
die of this disease, an event of very rare occurrence m dogs. 
In dogs the inflammation subsides in a few days after the application 
of Goulard’s extract or dilute solutions of lead acetate. Scarification and 
disinfectant applications are of assistance in the early stages in pigs, but, 
if somnolence has appeared or suppuration set in, destruction of the 
external or even of the middle ear often follows and treatment is 
hopeless. For this reason fat pigs should be slaughtered at an early 
stage. 
(3.) (EDEMA OF THE FREE BORDER OF THE EAR 
_EXTERNAL CANKER (OTHEMATOMA). 
Rupture of blood-vessels, and extravasation of blood between the 
cartilage and skin of the external ear, is often brought about m long¬ 
eared dogs by the ears being rubbed or bitten, but more frequently from 
their being vigorously shaken to allay irritation consequent on otitis. 
As a rule the rupture occurs under the perichondrium, and the con¬ 
dition therefore, in the dog consists of sub-perichondrial blood extra¬ 
vasation. This usually remains fluid for a lengthened period, appears 
oftenest on the inner surface, less frequently on the outer, at times on 
both. From the position of the lesion, absorption is slow and usually 
incomplete. , , , 
Hoffmann, misled by the above facts, erroneously regarded the ex t - 
vasate as consisting of lymph. 
Symptoms. The dog holds its head on one side, and examination 
reveals a slightly painful, fluctuating swelling, sharply defined, rounded 
or longish, and varying in size from a bean to an orange. n 
incision liberates fluid or clotted blood, and displays the yellow white 
surface of the cartilage, which later becomes covered with granulations, 
which appear as little discrete red flecks, and gradually, during perhaps 
several weeks, spread over the exposed surface. Healing is tardy, and 
the parts generally remain thickened. Where the swelling is not opened 
it may persist indefinitely, and produce marked distortion. 
Treatment. In slight huematoma, absorption may be pioduced by 
massage, though operation is usually preferable. The inner surface of 
the ear is incised to the full extent of the swelling, the lining membrane 
completely removed, and the cavity disinfected. Catgut sutures are then 
passed completely through the external ear so as to bind toget e 
walls of the cavity, the knots being tied on the outer surface of the ear. 
To keep the edges of the wound clean, and bring about rapid healing, 
