416 DISEASES INVOLVING NERVOUS SYSTEM 



cannot always be found. This led to the former behef in 

 "idiopathic" tetanus. In cattle tetanus most commonly 

 follows • parturition 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 precau- 

 tion 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 

 to 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. 



Horse. — ^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 



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