610 INFECTIOUS DISEASES 



is quite constant in the different animals, although variations 

 occur occasionally. Five to seven days is the usual course; 

 it may be in exceptional cases as short as two days or as 

 long as ten or eleven days. There is but little difference 

 in the course of the two forms; usually dumb rabies runs a 

 longer course than the furious type. 



Differential Diagnosis.— There are quite a number of 

 diseases in small animals which might be confused with 

 rabies : (a) Diseases of the brain, particularly inflammations 

 involving the meninges and the cerebral substance itself. 

 In these cases irritability and nervousness are present, but 

 the tendency to bite, the aggressiveness, change in voice 

 and development of the paralysis in the same way are 

 absent. If there should be any doubt the animal must be 

 confined and observed for a few days when the differentia- 

 tion will not be difficult, (b) Canine distemper (nervous 

 form) sometimes simulates rabies, but the history of the 

 case, the other symptoms of distemper and the length of 

 the course of the disease will reveal the difference, (c) 

 Parasites in the intestinal tract often produce certain 

 nervous phenomena, but of different development and type 

 than rabies. Many of the characteristic symptoms of 

 rabies are absent, (d) Other parasites (Linguatula 

 rhinaria, Dioctophyme renale, Spiroptera sanguinolenta, 

 Otodectes cynotis) may produce certain nervous symp- 

 toms, but careful examination and observation of the 

 animal will readily distinguish the difference, (e) Foreign 

 bodies lodged between the teeth, around the tongue or in 

 the pharynx all induce salivation, hoarseness from the 

 accompanying edema and cause the mouth to remain open. 

 These cases should be examined very carefully to differ- 

 entiate them from rabies. In most of these cases it is 

 impossible to close the mouth, which is not true in rabies, 

 and there are no general symptoms. (J) Trigeminal or 

 facial paralysis is observed occasionally in the course of 

 distemper, or as an independent condition. In these cases 

 there are no other symptoms of paralysis, nor any general 

 symptoms. The course is longer and the animal remains 

 otherwise normal, (g) Epilepsy might be confused with 



