DISEASES OF THE NERVOUS SYSTEM. 127 



Tetanus consists of a continued spasm of the voluntary muscles. The 

 spasmodic contraction of the muscles, although persistent, is sometimes 

 greater or more severe than the average during the course of the dis- 

 ease. The exacerbations, or increase of the violence of the spasm, may 

 occur without any cause other than the nature of the disease itself, but 

 they are frequently due to noises or the manner of going about the 

 animal by those in attendance, and to other causes that excite the 

 patient. 



Other technical terms are used to designate the particular forms of 

 tetanus, but they only refer to the regions of the body that are involved 

 in the spasm. Thus if the muscles of the head, particularly those 

 used in mastication (or chewing), are affected, it is called trismus; and 

 it is this form which gives rise to the popular name u lockjaw." When 

 the muscles of the upper part of the neck and back are affected the 

 head and tail are elevated, and the name applied is opisthotonos. If 

 the muscles of one side only are affected, the head is drawn to that 

 side, and the disease is called tetanus lateralis or pletirosthotonos. If 

 the muscles on the lower part of the neck and body are affected, the 

 mouth is drawn towards the breast, when the term einprosthotonos is 

 applied. In cattle the disease is characterized by the symptoms of 

 trismus and opisthotonos combined; the other forms have never been 

 met with in the experience of the writer. 



Two varieties of tetanus have been universally recognized : When the 

 disease exists in connection with a visible wound, it is called traumatic 

 tetanus. When no wound is discoverable the affection is called idio- 

 pathic tetanus. The writer is of opinion that these distinctions are 

 superfluous, by which he means to infer that in all cases the disease is 

 from the same cause. In the great majority of instances there is no 

 difficulty in finding a wound, and in many cases more than one wound. 

 In the cases called idiopathic one can only say that no wound is dis- 

 covered ; one can not say positively that no wound exists. There may 

 be a wound in the mouth, or in any part of the intestinal canal. When 

 it is considered how small the wound is in the foot from the prick of a 

 nail in so many cascx followed by lockjaw in the horse, it is not dillicult 

 to recognize the fact that there may be many small wounds that are 

 invisible about an animal. It is a familiar opinion often expressed 

 that there is danger in a pin-scratch. One may easily appreciate the fact 

 that there may be more small scratches than one on the hide of an ani- 

 mal thickly covered with hair, that will defy detection unless the animal 

 is shaved. Holding the.se views, the writer will not differentiate 

 tatween the, two varieties, but will describe the disease under the gen- 

 eral name, tetanus. It must be understood that the writer has no 

 desire to do violence to the opinions of others; nor docs he so strongly 

 assert his own opinions merely for the purpose of airing them; the real 

 objiM-t is that the most careful examination be made in every instance, 

 HO that eases \vill not be classed as idiopathic simply because a casual 

 glance over the animal fails to detect a wound. 



