360 INTERNAL CANKER, OTORRHEA, OR 



surface of the ear is incised to the full extent of the swelling, the 

 contents removed, and the cavity disinfected. Catgut sutures are 

 then passed completely through the external ear so as to bind 

 together the 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, the wound may be painted with tincture of 

 iodine and dusted with iodoform. Healing is further assisted by 

 binding the ears close to the head with a broad bandage, or by using 

 a net. This disease must be distinguished from the next in series. 



(3.) INFLAMMATION OF THE EXTERNAL AUDITORY 

 MEATUS. OTORRHCEA. 



This is termed in Germany " internal canker," in contradistinction 

 to the ulcerative and chronic inflammatory processes of the cartilage 

 of the ear, which have been described as " external canker." To 

 avoid mistakes, it would be better to discontinue the use of the terms 

 otitis externa and interna. 



The meatus extending from the auditory opening to the tympanic 

 membrane has externally a cartilaginous foundation, internally a 

 bony one. It is lined by skin, rich in wax glands. 



In order to view the largest possible portion of the meatus, the head 

 is placed downwards, the cartilage grasped with both hands, and held in 

 such a position as to direct the passage, which lies sideways, somewhat 

 towards the front. The aural speculum is of no great value in dogs, as 

 the tympanum is not visible. The resistance of the animal, moi cover, 

 interferes both with the insertion of the instrument and the examination. 



Causes. In dogs with long ears, ocasionally in other animals, 

 the waxy secretion decomposes in consequence of exclusion of air, 

 restricted evaporation, and infection, and produces irritation of 

 the lining of the meatus. Inflammation is seldom caused by the 

 entry of foreign bodies into the external auditory opening, though 

 Hering and others have met with acari in the canal. Although 

 examining many dogs suffering from otitis externa, Moller has 

 never found acari in the external meatus, but has seen the disease 

 caused by dermatocoptes cuniculi in rabbits, and Ziirn states that 

 dermatophagus cuniculi produces the same result. Cadiot ascribes 

 parasitic otitis in the dog and cat to the presence of Chorioptes 

 auricularum and in the goat and rabbit to Psoroptes communis. 

 Ostertag found bird-lice (Gamasus auris) in the external meatus of 

 a cow : attention was drawn to the animal by its violently shaking 

 its head. In dogs facial eczema sometimes invades the external ear, 

 and, on the other hand, otorrhcea may produce eczema on the ear. 



