130 THE HOUSE AND ITS DISEASES. 



Wounds in the leg, producing solution of continuity 

 of the nervous filaments, iiTitation from worms in the 

 alimentary canal, as likewise the operation for docking 

 and nicking, are the most frequent causes of this obstinate 

 and fatal disease. From whatever causes it may arise, 

 the brain and spinal cord are undoubtedly its principal 

 seat. The "rationale" of this fearful remedy is this — 

 a wound in a part favourable to the maintenance of 

 prolonged irritation, is capable of exciting a particular 

 region of the spinal cord, from which the state of excite- 

 ment spreads, so as to involve not only the whole cord, 

 but also the medulla oblongata, and in this state a large 

 portion of the motor nerves participate, so as to induce 

 tonic contraction of the muscles they supply. 



Tetanus 

 Consists not in an inflammatory affection of the cord, or 

 in its membranes, nor in congestion of them, but simply 

 in a state of prolonged physical excitement the natural 

 polar force of the centre being greatly excited, and kept 

 so by the constant irritation propagated to it by the 

 nerves of the wounded part. 



Symptoms. — Tetanus, consisting in a constant spasm 

 of the muscles of the head, neck, and spine, is slow in 

 making its appearance. The horse does not feed well, 

 partly chews, and drops its food and gulps water. The 

 motion of the jaws is observed to be limited, and some 

 saliva escapes from the mouth ; this stage would be the 

 most appropriate for administering medicine, but unfortu- 

 nately, it is of short duration — perfect rigidity of the 

 voluntary muscles, and closure of the jaws, quickly 

 supervene. The head is generally protruded, and cannot 

 be bent ; the eye is retracted within its socket, with the 

 haw projecting over it; the nostrils are expanded, the 

 ears erect, and the countenance expressive of anxiety 

 and extreme agony ; the tail is erect and quivering ; 

 the hind-legs spraddling, and the fore-legs projecting 

 like a stool ; the pulse is at first normal, but soon 



