INJURIES OF THE EXTERNAL EAR. 357 



growth can seldom be removed, and a fragment is usually left which 

 leads to a return of the condition or to fistula 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 recom- 

 mends 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 The contents are first withdrawn with a 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 pre- 

 cautions being observed. Should suppuration not occur within 

 three or four days, as can be ascertained 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 

 interior with the Pacquelin cautery. The necrotic portions are shed 

 and the cavity fills up with granulations. 



VI.— DISEASES OF THE EAR AND GUTTURAL POUCHES. 



(1.) WOUNDS OF THE EXTERNAL EAR. 



Injuries of the external ear are commonest in dogs, though seen 

 in 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. 



Cellulitis of the external ear is seldom seen in domestic animals 

 other than the dog and pig. Pofeld saw a cow which lost a large 

 portion of both ears from septic cellulitis. In dogs the condition 

 usually results from excoriations of the external ear, due very 

 frequently to otitis externa. Bites are a rare cause. On the other 

 hand, cellulitis of the external ear is a common disease in herds of 

 swine. Young pigs often bite each other's ears, producing a disease 



