TETANUS— LOCKJAW 377 



always be found. This led to the former belief in " idiopathic 

 tetanus." In cattle tetanus most commonly follows parturi- 

 tion where rough manipulations have been made to relieve 

 dystocia. Newborn animals may become infected through 

 the navel. The practice of docking lambs leads to tetanus, 

 the infection entering the fresh tail stump . Limited enzootics 

 of tetanus have occurred among horses, swine and sheep where 

 castration without sufficient precaution was practised in 

 infected districts. 



Necropsy. — There are no constant lesions found on post- 

 mortem. The brain and cord present nothing characteristic. 

 The condition of the wound through which the infection 

 entered is very varied. Usually it is not granulating well 

 and there is little pus discharge. The nerves are often bruised, 

 congested and swollen. If the infection was through the 

 umbilicus (tetanus neonatorum) the navel may be inflamed. 

 One attack of tetanus does not produce immunity. A 

 given animal may suffer more than once from the disease. 



Symptoms. — The period of incubation is usually from one to 

 two weeks. A minimum period of twenty-four hours has 

 been noted in very young animals and exceptionally in older 

 ones. As a rule the disease reaches full development in one 

 or two days. During the prodromal stage the patient is 

 stiff, does not care to move and shows loss of appetite or at 

 least slow mastication. The ears are held erect. If the head 

 of the patient is elevated a protrusion of the nictating mem- 

 brane over the eye occurs, a symptom most pronounced in 

 the horse. Tetanus may be partial, involving only parts of 

 the body (partial tetanus) or it may be general, affecting the 

 whole body (universal tetanus). In some cases the muscular 

 spasms are confined to the head and neck; in others the hind 

 parts; in still others the whole body is involved. 



Hdrse. — When the symptoms are fully developed and the 

 reflexes stimulated by excitement the patient assumes a 

 characteristic attitude : The legs are spread and stiff, the neck 

 and head are extended and the tail elevated. The ears stand 

 erect approaching each other, the eyes retracted and in part 

 covered by the nictating membrane. The pupils are dilated, 

 the nostrils distended and the nasal wings trumpeted. The 



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