310 



DISEASES OF TRUE INFECTION 



"\Micn these microbes invade a wound they midtiply with great rapidity 

 and produce toxines which cause a strychnine-like convulsive contraction 

 of the muscles. The virulence of the bacilli is in all probability influenced 

 by the simultaneous invasion of other germs. 



This very rarely occurs in the dog. The figure here presented (Fig. 

 100) is the only one the writer has seen, and was taken twenty-four 

 hours l:)efore death; the muscles w^ere contracted to such an extent 

 that the animal could be lifted bodily by holding up one anterior limb. 

 Tetanus may originate from a wound in any part of the body. No special 

 class of wound can be said to be favorable to the production of tetanus. 



Fig. 100. — Dog with tetanus. 



It may originate from a scratch or from a very large wound. The 

 temporary trismus seen in young animals that have eaten decayed meat 

 should be classed under ptomaine poisoning, and not under tetanus. 

 The anatomical examination is almost always negative; hypera^mia 

 and congestion of the cord which is occasionally seen is of secondary 

 importance as it seems to have no actual bearing on the true cause of the 

 disease. 



Symptoms. — The period of inctd)ation in a dog is not known posi- 

 tively, as the cases are so rare, but probably it is about the same as a 

 horse — from five to twenty days — depending probably on the vir- 

 ulence of the bacilli. The general symptoms are stiff stilty gait, the neck 

 and head are extended, the expression is staring and anxious, the ears are 

 drawn forward and pointed, the membrana nictitans is draw^n over the 

 eye, wrinkling of the skin of the f9rehead, retraction of the angle of the 



