LOCK- JAW, OR TETANUS. 379 



tion is fulfilled by using such remedies as act by altering 

 the susceptibility of the part, which are purges, and other 

 evacuants, whose action diminishes the excess of power ; 

 these last therefore are proper in plethoric subjects, or 

 when the spasm is united with vascular action. When, on 

 the contrary, the spasmodic affection attacks a debile part, 

 we use stimulants, to bring the part to a state to resist the 

 impressions. 



LOCK-JAW, OR TETANUS. 



Tetanic spasm differs from all the affections we have 

 lately noticed, inasmuch as the muscular contractions are 

 not alternated, with periods of relaxation ; on the contrary, 

 here they remain permanent, or with very little, and never 

 entire, remission. Lock-jaiv, so called from the rigid clo- 

 sure of the mouth, may be considered as a morbid irritation 

 of the whole or a part of the nervous system. 



Idiopathic tetanus is the most frequent in the horse, and 

 its causes are all of them, more or less, conjectural, never 

 self-evident. One of the most common is that of cold ; 

 particularly when the heat of the body is abstracted by 

 evaporation, or when moisture is applied to a relaxed 

 system : thus it has followed plunging into a river during 

 a run in the hunting season, or injudiciously allow- 

 ing a horse to stand still during a check after a severe 

 burst ; and more particularly it has been brought on by 

 a partial but continued application of water, as when it 

 makes its way through the roof of a building and falls in a 

 continued drip on the body ; even the drippings from the 

 eaves of a hay-rick, standing in the field in which a horse 

 was grazing, has produced it. It has succeeded visceral 

 affections, and is supposed to be occasionally the effect of 

 worms within the alimentary canal. Traumatic or sympto- 

 matic tetanus is the consequence of some external injury, 

 and it follows all kinds of lesions. Castration, nicking, 

 docking, punctures, particularly of the feet ; lacerations, 

 and even contusions, will bring it on. The size of the 

 wound is of no consequence : it may ensue upon the 

 smallest abrasion ; and it may not follow the largest possible 

 lesion. Cuts or bruises upon the orbital arch, where the 

 nerve emerges from the bony ring, immediately above the 



