324 MANUAL OF EQUINE MEDICINE. 



towards the heart, and the spine arched backwards, the 

 condition is spoken of as emprosthotonos. 



This latter condition is very rarely met with in horses, 

 but has been observed on one occasion at any rate, 

 being produced by rigid contraction of the inferior 

 muscles. 



Generally, however, in the horse trismus with opistho- 

 tonos is the condition met with ; pleurosthotonos is some- 

 times, though not frequentl}^, observed. 



Tetanus may be acute, sub-acute, or chronic. 

 When this affection owes its origin to a wound, it usually 

 manifests itself in from ten to twenty-eight days after the 

 infliction of the injury. 



Generally there is first noticed a stiffness about the neck 

 and lower jaw, and of the muscles near the seat of injury, 

 and there is difficulty in mastication and deglutition, to- 

 gether with increase of the secretion of saliva, and a peculiar 

 champing of the teeth. 



If the head be suddenly elevated, or the horse suddenly 

 disturbed, there is a characteristic protrusion of the mem- 

 brana nictitans over the eyes, which are withdrawn within 

 the orbits, thus causing the animal to show the white con- 

 junctival surface at every convulsive retraction. 



As the disease advances, the stiffness becomes more 

 marked, especially in the muscles of mastication and in 

 those of the upper part of the neck, and soon spreads to 

 other groups of voluntary muscles, especially those of the 

 abdomen, back, and hind-quarters. 



At length the tetanic condition becomes fully established, 

 and is very apparent even to a superficial observer. 



The limbs are extended, and kept apart; the tail is 

 elevated, and the animal moves in a peculiar, stiff, straddling 

 way, with difficulty and pain. 



The pulse is generally not much affected in the first in- 



