286 HERNIA. 



being naturally unduly wide. The superior inguinal ring becomes 

 dilated if the hind le^: of its side is extended backwards and out- 

 wards. 



PREDISPOSITION. — Climatic heat is a strong predisposing 

 cause, by its relaxing effect on the tissues, Avhich in entires suffer- 

 ing from inguinal hernia, is aided by the fact that in hot countries 

 the testicles hang lower down, than in temperate or cold ones, 

 and thus increase the pressure of their cords on the respective in- 

 guinal canals. H. Bouley states that inguinal hernia is more 

 common in hot weather than in winter. Inguinal hernia is not 

 uncommon among entire horses ; but is extremely rare among geld- 

 ings ; for the cord, when freed from the weight of the testicle, 

 ceases to exert its customary pressure on the interior surface of 

 the inguinal ring, which it, on retracting, also appears to help 

 in blocking up. In mares, the blood-vessels (of the udder) which, 

 on each side, pass through the inguinal canal, are so closely sur- 

 rounded, at the superior inguinal ring, with folds of peritoneum, 

 that neither the intestine nor its membranes can get through that 

 opening, without these protecting folds being previously torn 

 asunder. Consequently, mares hardly ever suffer from inguinal 

 hernia. There may be congenital predisposition which is not suffi- 

 cient to give rise to it without an exciting cause. Signol states 

 that mules are more liable to this form of hernia than donkeys. 

 It occurs more often on the left side than the right; because the 

 folds of the small intestine occupy chiefly the left flank. 



THE GENERAL SYMPTOMS OF ACUTE INGUINAL HERNIA 



are : suddenness of attack ; colicky pains which rapidly increase 

 in intensity ; movements indicative of trying to relieve the hernia, 

 such as arching the back, repeatedly stretching the muzzle forwards 

 and upwards and then bringing it down, lying on the back, or 

 sitting on the ground like a dog; pawing the ground; and breaking 

 out in patches of sweat. H. Bouley states, that, if the hernia 

 remains unrelieved, the intestinal pains will disappear between the 

 fifteenth and twentieth hour after the symptoms of uneasiness have 

 commenced, on account of mortification, and consequently insen- 

 sibility, of the bowel setting in. The local symptoms of acute in- 

 guinal hernia are : thickening of the cord, the component parts of 

 which will be found to be bound together and incapable of being 

 freely separated from each other by the fingers; filling, after a 

 few hours, of the lower part of the scrotum with fluid from the 

 congested blood-vessels ; coldness of the scrotum from arrest of cir- 

 culation ; drawing up of the testicle ; and, at first, pain on manipu- 



