HERNIA AT THE NAVEL. 291 



Hernia at the Navel {Umbilical Hernia). 



This form of hernia is the protrusion through the navel, of 

 bowel or of its connecting membrane. It is consequently situated 

 in the middle line of the abdomen and can scarcely escape the 

 observation of the most inexperienced person. 



CAUSES. — Hereditary predisposition is well marked in this 

 complaint. It may exist at birth, but this so-called congenital 

 hernia may very probably be the result of the pulling which the 

 navel-string underwent at the time of foaling. However it may 

 be, umbilical hernise usually occur during the first two or three 

 months after birth ; that is to say, while the opening at the 

 navel is becoming obliterated, and the tissue at that place 

 is becoming consolidated. They can, however, appear later, 

 and may resiilt from more or less violent strains done when the 

 foals are jumping and playing. At other times, these strains are 

 induced by intestinal irritation, accompanied by diarrhoea, or 

 constipation with straining. But, however the strain may take 

 place, the abdominal muscles contract and push the intestines 

 towards the wall of the belly. Then, if they find an opening, or 

 even a weak spot, like the ring of the navel while it is undergoing 

 the process of becoming blocked up, they select it, and a hernia 

 is produced. 



SYMPTOMS. — This hernia, the situation of which clearly shows 

 its character, may vary in size from that of a hen's egg to that 

 of an ostrich's egg, or even bigger, and may be hemispherical or 

 pear-shaped. The tumour, if pressed upon with the hand, espe- 

 cially if the animal is placed on his back, will disappear, to return, 

 however, when the pressure is removed. If it be composed of in- 

 testine, it will be soft and elastic when the bowels are empty, and 

 doughy when they are full of semi-solid matter. In any case, the 

 tumour will feel more elastic when composed of intestine, than 

 when formed of its connecting membrane, which, naturally, will 

 not vary in consistence. If intestine be present, movements and 

 abdominal rumblings may be detected in it. This hernia rarely 

 gives rise to. serious consequences ; because its contents are com- 

 posed of large intestine (colon) and omentum, neither of which is 

 in this position liable to become strangulated. It may, however, 

 become engorged and inflamed from injury. Its existence natu- 

 rally depreciates the value of an animal suffering from it. 



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