INFLAMMATION OF THE EXTERNAL EAR. 



379 



Fig. 84. 



and an exudation of a serous and, later, a purulent secretion, in 

 the chronic course. We may also have the formation of abscesses 

 and contraction of the meatus (caused by thickening of the cutis, 

 by granulations, and by polypous malformations). Although we 

 may have acute inflammation of the canal extending deep into the 

 lining, it is very rare that the tympanic membrane becomes ulcer- 

 ated and perforated. 



Etiology. The causes are similar to those mentioned under 

 eczema. It is due to an accumulation of cerumen, dirt, and cuta- 

 neous scabs. It is also recognized that otitis is produced by acari. 

 (See Parasitic Otitis, page 381.) Hoffmann states that he has 

 observed serious suppuration in cases where dogs' ears have been 

 clipped too close to the head. 



Clinical Symptoms and Prognosis. The animals shake 

 their head, and, as the disease is almost invariably located in one 

 ear only, they hold their head in an oblique position, trying to 

 scratch the head against the base of the ear or to 

 rub it against some object. They avoid carefully 

 any attempt which is made to touch the ear, and 

 show great pain when the tube of a concha is 

 touched. In examining the external ear we use a 

 forceps- shaped speculum or ear-mirror (Fig. 84). 

 If we distend the canal, we generally find it filled 

 with a fetid, grayish-green, or reddish liquid consist- 

 ing of glandular secretions, fungi, cutaneous scabs, 

 pus, acari, etc. After the organ is cleaned out we 

 find an intensely red, swollen, sometimes ulcerating 

 surface of the skin. In advanced cases the meatus 

 is almost entirely closed by thickening of the cutis. 

 Numerous granulations appear quickly, and in some 

 cases where both ears are affected we may have 

 symptoms of impaired hearing or deafness. According to Hoff- 

 mann, in deep suppurating conditions we hear a characteristic 

 smacking or sucking liquid sound, which is produced by side 

 pressure or rapid compression on the base of the ear. 



The general condition is very seldom affected. Vomiting is 

 only observed in exceptional cases. Vertigo, spasms, and epilep- 

 tiform symptoms sometimes follow where acari are present in 

 enormous numbers. 



