112 VETERINAKT MEDICINE AND SURGERY. 



TETANUS. 



Synonyms. — Lockjaw; Trismus. 



Definition. — Tetanus is a persistent contraction without any relaxa- 

 tion or alternation of the voluntary muscles; when the affection is confined 

 to the jaws, it is termed trismus. 



Etiology. — The immediate cause of tetanus is some abnormal condi- 

 tion of the nerves and their peripheral centres. A part of the brain, and 

 the spinal cord in particular, either partially or throughout, is involved. 



Tetanus is most commonly induced by picking up rusty nails or other 

 bits of iron, causing an injury to the sensitive portion of the foot. 



It also follows, at times, surgical operations; docking has been known 

 to induce it in a number of instances. The inflnence of local circumstan- 

 ces and meteorological conditions are recognized in causing a tendency 

 to tetanus. 



Why, or under what circumstances injury to the end of a nerve will 

 produce this terrible disease, is, as yet, wholly inexplicable. Tetanus re- 

 sulting from any such cause is termed '* traumatic." 



It also arises not infrequently from any sudden chill to the back or loins, 

 such as that caused by a horse being left to stand in a draught whilst 

 sweating, especially if the saddle has been removed. When there is no 

 external or at least no perceptible external injury, the disease is termed 

 ^'idiopathic." 



When the muscles of the face and jaws alone are affected it is termed 

 "Trismus." 



Symptoms. — The attack is characterized by more or less closure of 

 the jaws, sometimes the teeth are firmly fixed together, great difficulty 

 in swallowing, rigidity of the limbs and extreme difficulty in moving. 

 The animal also pokes out his nose, as if suffering from sore throat. As 

 the disease advances, the jaws become so tightly locked that neither food 

 nor medicine can be introduced through them. 



Within three or four days and sometimes earlier, the symptoms reach 

 their height. The ears are erect and turned forward, the eyes are retracted, 

 and the haw is partially protruded over them. Fig. 70. The nostrils are di- 

 lated. The animal stands persistently, his legs are stretched wide apart and 

 look more like wooden stilts than living structures. The tail is upraised, the 



