176 DISEASES OF CATTLE. 



ning nooses, are successively introduced and made fast on two limbs 

 of the calf; the cords are then passed through the two rings on the 

 end of the instrument, which is passed into the womb and the cords 

 drawn tight and fixed round the handle. Then, using the handle as a 

 lever, it is turned in the direction opposite to the twist. The hand 

 should meanwhile be introduced into the womb and the snared limbs 

 seized and pressed against its walls so as to secure the rotation of the 

 uterus along with the body of the fetus. The relaxation of the con- 

 striction and the effacement of the spiral folds will show when suc- 

 cess has been gained, and the different members at one end of the body 

 should then be brought up so as to secure a natural presentation. 



NARROW PELVIS FROM FRACTURE OR DISEASE. 



In a small cow the pelvis may be too narrow to pass a calf sired by 

 a bull of a large breed, but this is exceptional, as the fetus usually 

 accommodates itself to the size of the dam and makes its extra growth 

 after birth. IVlien the pelvic bones have been fractured repair takes 

 place with the formation of a large permanent callus, which, project- 

 ing internally, may be a serious obstacle to calving. Worse still, if 

 the edge of the broken bone projects internally as a sharp spike or 

 ridge, the vaginal walls are cut upon it during the passage of the 

 calf, with serious or fatal result. In other cases, where the cow has 

 suffered from fragility of bone (fragilitas ossium) the thickening of 

 the bone causes narrowing of the long passage of the pelvis and the 

 crumbling fractures poorly repaired, with an excess of brittle new 

 material, may form an insuperable obstacle to parturition. Cows 

 affected in any of these ways should never again be bred, but if they 

 do get pregnant and reach full time a careful examination will be 

 necessary to determine whether natural parturition can take place 

 or if the calf must be extracted in pieces. (See "Embryotomy," p. 

 200.) 



OBSTRUCTION BY MASSES OF FAT. 



This is not unknown in old cows of the beef breeds, the enormous 

 masses of fat upon and within the pelvis being associated with weak- 

 ness or fatty degeneration of the muscles. If the presentation is 

 natural, little more is wanted than a judicious traction upon the 

 fetus to compress and overcome the soft resisting masses. 



OBSTRUCTION BY A FULL BLADDER OR RECTUM OR BY STONE. 



In all cases of delayed or tardy parturition the evacuation of 

 rectum and bladder is important, and it is no less so in all difficult 

 parturitions. Stone in the bladder is fortunately rare in the cow, 

 but when present it should be removed to obviate crushing and 

 perhaps perforation of the organ during calving. 



