RABIES. 403 



Spasms of the muscles in different parts of the body are also seen 

 at intervals. About the fourth day the animal usually becomes 

 quieter and the walk is stiff, unsteady, and swaying, showing that 

 the final paralysis is coming on. This is called the paralytic stage. 

 The loss of flesh is extremely rapid, and even during the short 

 course of the disease the animal becomes exceedingly emaciated. 

 The temperature is never elevated, it usually i-emaining about nor- 

 mal or even subnormal. Finally, there is complete paralysis of 

 the hind quarters, the animal being unable to rise, and but for 

 irregular convulsive movements lies in a comatose condition and 

 dies usualh^ from the fourth to the sixth day after the appearance 

 of the first symptom. 



Anatomy. — If animals which have succumbed to rabies are ex- 

 amined post mortem, very slight evidence of disease will be found 

 in any of the organs, and, indeed, the absence of any specific lesions 

 may be considered as characteristic. The blood is dark and imper- 

 fectly coagulated. The throat is frequently reddened, and there 

 may be small spots of extravasated blood in the intestines. The 

 stomachs are usually empty. In the spleen there may be hemor- 

 rhagic enlargements (infarcts). The cadavers rapidly undergo 

 decomposition. 



Different'ml diagnosis. — It is not an easy matter to decide definitely 

 that a given animal has rabies, since the symptoms given above be- 

 long in part to a variety of other diseases, among which may be men- 

 tioned the excitement seen in young animals following close confine- 

 ment, certain vegetable and mineral poisons, acute enteritis, and 

 alterations of the central nervous system in cattle, the most common 

 of which is tuberculosis of the brain and its covering membranes. 

 The post-mortem lesions, however, should assist in making a correct 

 diagnosis. Tetanus may readily be differentiated from rabies by the 

 persistence of muscular cramps, especially of the face and abdomen, 

 which cause these muscles to become set and as hard as wood. In 

 tetanus there is also an absence of a depraved appetite or of a willful 

 propensity to hurt other animals or to damage the surroundings. 

 The cow remains quiet and the general muscular contraction gives 

 her a rigid appearance. There is an absence of paralysis which 

 marks the advanced stage of rabies. The form of dumb rabies in 

 dogs is characterized by the paralysis and pendency of the lower 

 jaw, while in tetanus the jaws are locked. This locking of the jaws 

 in cattle renders the animal incapable of bellowing, as in rabies. 

 Finally, tetanus may be distinguished from rabies by the fact that 

 the central nervous system does not contain the infectious principle, 

 while in rabies the inoculation of test rabbits with the brain or cord 

 of a rabid animal will produce the disease with characteristc symp- 

 toms after an interval of 15 to 20 days. This period of incubation 



