284 HERNIA.. 



being naturally unduly wide. The superior inguinal ring becomes 

 dilated if the hind leg of its side is extended backwards and out- 

 wards. 



PREDISPOSITION.— Climatic heat is a strong predisposing 

 cause, by its relaxing effect on the tissues, which in entires 

 suffering 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 

 inguinal canals. Inguinal hernia is more common in hot weather 

 than in winter. Inguinal hernia is not uncommon among entire 

 horses ; but is extremely rare among geldings ; 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 surrounded 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 bei congenital pre- 

 disposition which is not sufficient to give rise to it without an 

 exciting cause. 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. If the hernia remains un- 

 relieved, the intestinal pains will disappear between the fifteenth 

 and twentieth hour after the symptoms of uneasiness have 

 commenced, on account of mortification, and consequently in- 

 sensibility, of the bowel setting in. The local symptoms of acute 

 inguinal hernia a,re : 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 circulation ; drawing up of the testicle ; and, at first, 

 pain on manipulation of the part, succeeded, towards the end, by 



