EAR FISTULA 495 



DEAFNESS. 



Etiology. This condition is observed from diseases affecting 

 the internal ear, from closure of the external canal or it may 

 be congenital. Paralysis of the auditory nerve may be the 

 result of general infection (distemper) or ptomain poisoning. 

 Deafness is noted very commonly in puppies, sometimes 

 several in a litter will be affected. This no doubt is due to 

 improper development of the auditory nerve or other struct- 

 ures of the internal ear. The condition is acquired in some 

 cases from disease processes and infection extending to the 

 internal ear. Complete closure of the external canal will 

 produce at least a temporary deafness. 



Symptoms. The most pronounced symptom is failure to 

 obey commands. Puppies deaf from birth do not bark or 

 make any definite sounds. In congenital deafness the 

 examination will reveal nothing abnormal with the external 

 ear. In acquired deafness in some cases the cause may be 

 found, such as closure of the external canal. 



Prognosis. Unfavorable in all cases of congenital origin 

 or in cases due to external infection or parasites entering and 

 destroying the internal ear. It is favorable in some cases 

 of closure of the external canal with cerumen or tumor 

 formation. 



Treatment. In congenital deafness no treatment seems to 

 be of any value. If the deafness is due to paralysis of the 

 auditory nerve small doses of strychnin would be recom- 

 mended (0.001 once daily). Examination of the external 

 meatus should be made and, if closed, it should be dilated 

 and the cause removed. 



EAR FISTULA. 



Etiology. Dentigerous cysts are occasionally found in the 

 temporal region and have their opening in the auditory canal. 

 Wounds of the cartilage of the ear, either from sharp objects 

 penetrating this region or from other causes may lead to a 

 fistulous opening. 



