D YSTOKIA B V PEL VIC CONSTRICTION. 273 



croup had become altered in form; it was depressed, and the attachment of the tail 

 was low, while the ligamento-cartilaginous substance which united the sacrum to the 

 ossa innominata had been partially torn, causing the croup to approach almost two 

 inches nearer to a horizontal position. 



Exostoses. 



Exostoses on the pelvic bones, and particularly when they project into 

 the pelvic cavity, or encroach on its openings, may become a more or less 

 serious obstacle to the passage of the fcetus. 



Favre, of Geneva, states that bony tumors situated beneath the croup, 

 at the inner and upper surface of the pelvis, render parturition difficult, 

 even if they are not large and near the root of the tail. He adds that 

 such cases are not rare in old Mares. 



Fractures. 



Like the exostoses, more or less completely consolidated fractures of 



Fig. 65. 

 Pelvic Exostosis. 



the sacrum or coxae, which have been united by an irregular callus, may, 

 for the same reason, prove an obstacle to birth. As animals suffering 

 from a fracture of any of the bones of this region are often destroyed, 

 laborious parturition from such a deformity is not so frequent as from 

 some other causes ; nevertheless, it does occur now and again. 



It must be remembered that fractures of the pelvic bones are some- 

 what frequent in animals, and may occur at any part. The most common 

 seat of fracture is perhaps the external angle of the ilium ; and the least 

 frequent, the posterior part of the ischium and the pubis. Fracture of 

 the sacrum and the internal angle of the ilium is also very rare. Simul- 

 taneous compound fracture of the two coxal bones has been observed 

 in two cases by Lafosse ; in one case by Crepin, and in another by 

 Philippe. 



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