DISEASES OF THE NERVOUS SYSTEM. 325 



lise to tetanic or constant contraction of the muscles. The 

 gernns enter the system through some open wound, though 

 it is not always possible to trace the chain of events. It 

 is, fortunately, not common in the dog. 



When the muscles of mastication are involved it may be 

 impossible to give either food or medicine by the mouth. 



Treatment. — Perfect rest, quiet, sedatives, and nutri- 

 ment. Chloral hydrate, if necessary, by the rectum or by 

 hypodermic injection, nutrient enemata, and, later, stimu- 

 lants. Opium hypodermically may also be tried. The 

 prognosis is very bad. Death may result froni exhaustion, 

 or from suffocation owing to failure of the respiratory 

 muscles. Anti-toxic serum from immunized animals is 

 now on trial. 



Chorea. — We do not know the essential pathological 

 condition underlying those irregular, more or less con- 

 stant, muscular movements that go by the name St. Yitus's 

 dance, megrim, chorea, etc. These irregular, involun- 

 tary discharges of the motor-cells may apparently be due 

 to many causes. 



Usually only certain groups of motor nerve-cells, and 

 consequently only certain groups of muscles, are affected. 

 The movements may or may not cease during sleep. 

 Generally there are no febrile symptoms, and the animal's 

 health may seem to be otherwise perfectly good. 



It is certainly associated with the presence of worms 

 in the intestinal tract in some instances, but it most fre- 

 quently is a sequence of distemper. It may also follow 

 on nervous shock from fright, as when a dog is thrown 

 into water ; against which, and against plunging rashly into 

 a bath-tub without any warning, we wish to protest. 



