392 HORSE, SWINE AND POULTRY DISEASES 



part of the sympathetic nervous system, and they usually indicate 

 an excessive action of the reflex motor centers. Spasms may be in- 

 duced by various medicinal agents given in poisonous doses, or by 

 effete materials in the circulation, such as nux vomica or its alkaloid 

 strychnia, lead preparations, or an excess of the urea products in the 

 circulation, etc. Spasms may be divided into two classes: Tonic 

 spasm, when the cramp is continuous or results in persistent rigidity, 

 as in tetanus ; clonic spasm, when the cramping is of short duration, 

 or is alternated with relaxations. Spasms may affect involuntary 

 as well as the voluntary muscles, the muscles of the intestines, 

 and even the heart. They are always sudden in their development. 



Spasm of the Glottis. This is manifested by a strangling res- 

 piration ; a wheezing noise is produced in the act of inspiration ; ex- 

 treme anxiety and suffering for want of air. The head is extended, 

 the body profusely perspiring ; pulse very rapid ; soon great exhaus- 

 tion becomes manifest; the mucous membranes become turgid and 

 very dark colored, and the animal thus may suffocate in a short 

 time. 



Spasms of the Neck of the Bladder. This may be due to spinal 

 irritation or a reflex from intestinal irritation, and is manifested by 

 frequent but ineffectual attempts to urinate. 



Spasm of the Diaphragm, or Thumps. Spasmodic contraction 

 of the diaphragm, the principal muscle used in respiration, is gen- 

 erally occasioned by extreme and prolonged speeding on the race 

 track or road. The severe strain thus put upon this muscle finally 

 induces irritation of the nerves controlling it, and the contractions 

 become very forcible and violent, giving the jerking character known 

 among horsemen as "thumps." This condition may be distin- 

 guished from violent beating of the heart by feeling the pulse beat 

 at the angle of the jaw, and at the same time watching the jerking 

 movement of the body, when it will be discovered that the two bear 

 no relation to each other. 



Spasm of the Thigh, or Cramp of a Hind Limb. This is fre- 

 quently witnessed in horses that stand on sloping plank floors gen- 

 erally in cold weather or it may come on soon after severe exercise. 

 It is probably due to an irritation of the nerves of the thigh. In 

 cramps of the hind leg the limb becomes perfectly rigid, and at- 

 tempts to flex the leg are unsuccessful; the animal stands on the 

 affected limb, but is unable to move it ; it is unnaturally cold ; it does 

 not, however, appear to cause much suffering unless attempts are 

 made to change position. This cramp may be of short duration a 

 few minutes or it may persist for several days. This condition is 

 often taken for a dislocation of the stifle joint. In the latter the foot 

 is extended backward, and the horse is unable to advance it, but 

 drags the limb after him. An examination of the joint also reveals 

 a change in form. Spasms may affect the eyelids, by closure or by 

 retraction. Spasm of the stern o-maxi 11 aris muscle has been wit- 

 nessed, and the animal was unable to close the jaws until the muscle 

 became relaxed. 



