TETANUS. 511 



injure himself or anyone else, while we are waiting for the con- 

 firmation of our suspicion of rabies. 



PEEVEXTIVE MEASURES.— If we can take the animal in hand 

 shortly after the bite has been inflicted, we should freely cut away 

 the part, or destroy it with a red-hot iron, nitric acid, or lunar 

 caustic. If a bacteriological laboratory be within reach, protective 

 inoculation might be tried. 



As TREATMENT is of no avail after the symptoms have mani- 

 fested themselves ; the only thing to do is to destroy the affected 

 horse. 



Tetanus {Lockjaw). 



This is a state of continued contraction of the voluntary muscles,* 

 caused by the presence, in the animal system, of poisonous material 

 produced by a ferment formed by a specific disease germ (the 

 baccilus spilliformis of Nicolaier). 



NATURE OF THE DISEASE.— The microbes of tetanus are widely dis- 

 tributed over the face of the earth, and grow well in horse dung and on 

 marshy ground. Owing to the fact that they are frequently swallowed 

 along with forage, they can often be found in recently expelled dung. The 

 most favourable temperature for their development is about 70° F. They 

 act by means of extremely virulent poisons, which they manufacture, and 

 which cause the terrible and characteristic symptoms of the disease. In 

 fact, a case of tetanus is as much a case of poisoning as one caused by an 

 overdose of strychnine. The poisonous material of tetanus consists of at 

 least four different kinds of poison (tetanin, tetanotoxin, spasmotoxin, and 

 hydrotetanin), which become fixed in the brain and act on it. The violence 

 of the symptoms, other conditions being equal, appears to be proportionate 

 to the amount of poison received by the patient. 



Carougeau (Cadeac's " Encyclopedie Veterinaire ") tells us that in a state 

 of nature, the microbes of tetanus exist in the form of spores which do not 

 manufacture any poison. But if they are introduced into the animal tissues 

 under certain favourable conditions they go through a form of development 

 and subsequently secrete their toxins with the result of setting up this 

 disease. If these spores are inoculated by themselves into healthy tissue, 

 they are unable to produce their poisons for the time being, and will in all 

 probability be destroyed by the leucocytes (p. 15). Some of them may, 

 however, remain alive though inactive for even three months or more, and, 

 under conditions favourable to their development, they may subsequently 

 become virulent and produce tetanus. Hence, the fact that, occasionally, 

 the period of incubation is unusually long. The conditions in question appear 

 to be those which diminish the resistance of the tissues, by repelling the 

 protective leucocytes ; one of the chief of these conditions being the presence 

 of certain common microbes which produce pus and which favour the 



*NoTE. — ^Muscles are divided into voluntary and involuntary muscles. 

 The voluntary muscles, like those of the limbs and face, are under the 

 power of the will. The involuntary ones, like those of the intestines, heart, 

 and arteries, can perform their duties independently of such control. 



