300 FISTULA IN ANO. 



FISTULA IN ANO. 



This troublesome affection has been only witnessed in the 

 horse and ox. There are the so-called false fistulge in ano, 

 depending on disease of the pelvic bones ; and the true 

 fistula, which consists in a sinus formed beneath the anus on 

 the side of the rectum, and in some instances opening into 

 the latter; whereas in others it is blind, or terminating 

 abruptly at the coats of the intestines. When there is a free 

 opening from the rectum to the external surface the fistula 

 is said to be complete, and when there is but one opening, 

 and that cutaneous, the fistula is said to be a blind external 

 one ; whereas, in a few instances, though very rare in the 

 lower animals, a blind internal fistula exists, that is to say, 

 there is only an opening in the intestine communicating with 

 the sinus. The false fistulse in ano have always an external 

 opening, and they may be detected by probing, when the 

 grating of diseased bone is perceived. 



The disease commences by the formation of an abscess in 

 the angle between the rectum and ischium, and is usually due 

 to injury. I have seen an instance in which the abscess ex- 

 tended along the side of the pelvis and destroyed the animal 

 by pressure on the intestine, which induced obstruction. 

 The pus descended through the inguinal ring, and produced 

 inflammation on the inner surface of the thigh. I was called 

 to this horse when too late to afford any relief, and after 

 death about a gallon of pus was removed from the diffuse 

 cold abscess. But in ordinary cases the abscess points, and 

 discharges its contents through an opening close to the 

 sphincter; and whereas the animal is very stiff during the 

 development of the abscess, after it has burst the chief incon- 

 venience arises from pains in the act of evacuating faeces, and 

 at the same time the smearing of the tail and hind quarters 



