114 
FISTULA OF THE EAR. 
malar bone, over which the skin is freely movable. Sometimes cellular 
inflammation develops, followed by abscess formation, but producing 
no great disturbance. In horses of little value objection is accordingly 
raised to removal of the teeth. 
Treatment. AY here treatment is necessary the swelling is opened to 
the bottom, the tooth removed, the interior cauterised with chloride of 
zinc or chromic acid, 1 to 10, and recovery usually occurs in four to six 
weeks. Ligature of vessels is rarely necessary. When the tooth is deeply 
implanted in one of the cranial bones it may be removed with forceps, 
but in such case there is considerable danger of meningo-encephalitis, 
even though strict antisepsis be observed, and it is often preferable to 
1 ic. 63 . Pie-amieular fistula due to presence of a dentigerous cyst. 
renounce operation. The disease occurs very seldom in animals other 
han the horse. Verwey found a dental cyst on the petrous temporal 
bone of a dog, which suffered in consequence from otitis externa. 
. D ® rmo . ld cysts closely resemble those above described, and occur in 
simi ar situations, but usually contain a mass of deeply pigmented tissue 
more or less covered with hair. 
(6.) CHRONIC CATARRH OF THE GUTTURAL 
POUCHES. 
In the horse the mucous membrane of the guttural pouch consists of 
an extension of that of the pharynx. The Eustachian tube is about A of 
an inch m thickness, rich m mucous glands, and lined with ciliated 
epi le mm. The pouches possess a considerable area, and are attached 
