INJURY OF THE EXTERNAL EAR. 
107 
usually left which leads to a return of the condition or to listula 
formation. 
The treatment of these cysts is purely surgical. Removal of the cyst 
is followed by recovery, but the operation is very troublesome on account 
of the richness of the surrounding tissues in vessels and nerves. Moller 
claims to have had many successes after operation. In one case, 
however, in a dog, the animal gradually wasted, became dull, and died 
without at any time showing fever. 
On account of the difficulty of total extirpation Frohner recommends 
injecting 2 to 5 per cent, iodine solution, which produces suppuration in 
the cyst. The contents are first withdrawn with a small syringe and 
the iodine solution injected, no antiseptic precautions being obseived. 
Should suppuration not occur within three or four days, as can be ascei- 
tained by puncture, the iodine injection is repeated. As soon as pus is 
freely formed the cyst can be laid open and treated as a common abscess 
cavity. 
Owing to failures with this method Frick now prefers to lay open the 
cyst fully and suture the flaps to the neighbouring skin. He then 
carefully mops out the cavity and thoroughly cauterises the inteiioi with 
the Pacquelin cautery. The necrotic portions are shed and the cavity 
fills up by granulations. 
VI.—DISEASES OF THE EAR AND GUTTURAL 
POUCHES. 
(1.) INJURY OF THE EXTERNAL EAR. 
Injuries of the external ear are commonest in dogs, though seen m 
other animals. They are produced in cropping the ears and from bites. 
In long-eared varieties, shaking the head persistently may lead to 
injuries. Larger animals meet with wounds of the ears by bringing the 
head forcibly against nails or hooks, and occasionally by being bitten by 
their companions. The practice of applying a twitch to the ear, more 
common formerly than now, was also a frequent cause. 
Prognosis. The wound, when confined to the skin, is unimportant; 
but the cartilage being closely attached to the skin, often suffers, and may 
be more or less injured. In a horse Moller saw a torn wound extending 
from the base of the ear to its summit, and dividing it into two exactly 
equal portions. Transverse wounds occur, or pieces of the caitilage 
(recognised by its white colour) may be entirely lost. In long-eared 
dogs, the cartilage does not reach to the point of the ear, but is 
continued by a fascia-like membrane. Healing, easily effected if the 
parts are undisturbed, is often checked by the animal continually rubbing 
