TETANUS 159 



system through wounds of the skin, however slight. 

 The anaerobic properties of this bacillus make punc- 

 tured and penetrating wounds the most favorable 

 environment for its development. Suppurating 

 wounds are also favorable to the development of 

 the tetanus bacillus on account of the oxygen being 

 used up by the pyogenic organisms, so that the 

 deeper portions of the wound may be devoid of oxy- 

 gen, thus allowing anaerobic organisms to develop. 

 The organisms remain at the site of inoculation, the 

 symptoms being produced by the action of their 

 katabolic products or toxins on the nerve centers. 

 Tetanus is unusual in dogs, this animal being 

 rather less susceptible to the disease than is man 

 and far less susceptible than the horse. 



Symptoms. — The general symptoms of tetanus 

 are a greatly increased irritability of nervous reflex 

 and tonic spasms of the various muscular groups. 

 Trismus, ot spasms of the masticatory muscles, oc- 

 curs, causing the jaws to be firmly held together, 

 hence the popular name of "lockjaw." The recti 

 occulorum, when affected by spasm, cause the eyes 

 to retract within their orbits and the membrana 

 nictitans to protrude over the eyeballs. The whole 

 body becomes rigid; the extremities stiff and stilt- 

 like, the neck outstretched, and the tail elevated. 

 Breathing is interfered with by the spasm of the 

 inspiratory muscles. 



Depending upon which group of muscles is 

 mainly affected, the patient's body assumes various 

 positions when the spasms are present. The head 

 and tail may be elevated and the back depressed ; 

 the back may be arched and the abdomen tucked 

 up; or the body may be curved laterally. The tem- 

 perature is at first only moderately elevated, but 

 in cases approaching a fatal termination it may 



