188 DISEASES OF THE HORSE. 
position and presentation has been rendered natural, traction on 
the fetus must be made only during a labor pain. If a mare is 
inclined to kick, it may be necessary to apply hobbles to protect the 
operator. 
DirricULT PARTURITION FROM NARROW PELVIs.—A disproportion 
between the fetus got by a large stallion and the pelvis of a small 
dam is a serious obstacle to parturition, sometimes seen in the mare. 
This is not the rule, however, as the foal up to birth usually accommo- 
dates itself to the size of the dam, as illustrated in the successful 
crossing of Percheron stallions on mustang mares. If the dispro- 
portion is too great the only resort is embryotomy. 
Fracturep HIP BoNES.—More commonly the obstruction comes 
from distortion and narrowing of the pelvis as the result of fractures. 
(Plate XIII, fig. 2.) Fractures at any point of the lateral wall or 
floor of the pelvis are repaired with the formation of an extensive 
bony deposit bulging into the passage of the pelvis. The displace- 
ment of the ends of the broken bone is another cause of constriction, 
and between the two conditions the passage of the fetus may be ren- 
dered impossible without embryotomy. Fracture of the sacrum (the 
continuation of the backbone forming the croup) leads to the de- 
pression of the posterior part of that bone in the roof of the pelvis 
and the narrowing of the passage from above downward by a bony 
ridge presenting its sharp edge forward. 
In all cases in which there has been injury to the bones of the pelvis 
the obvious precaution is to withhold the mare from breeding and to 
use her for work only. 
If a mare with a pelvis thus narrowed has got in foal inadvert- 
ently, abortion may be induced in the early months of gestation by 
slowly introducing the oiled finger through the neck of the womb 
and following this by the other fingers until the whole hand has 
been introduced. Then the water bags may be broken, and with the 
escape of the liquid the womb will contract on the solid fetus and 
labor-pains will ensue. The fetus being small will pass easily. 
TUMORS IN THE VAGINA AND PELVIS.—Tumors of various kinds may 
form in the vagina or elsewhere within the pelvis, and when large 
enough will obstruct or prevent the passage of the fetus. Gray mares, 
which are so subject to black pigment tumors (melanosis) on the 
‘tail, anus, and vulva, are the most liable to suffer from this. Still 
more rarely the wall of the vagina becomes relaxed, and being pressed 
by a mass of intestines will protrude through the lips of the vulva 
as a hernial sac, containing a part of the bowels. Ifa tumor is small 
it may only retard and not absolutely prevent parturition. A hernial 
protrusion of the wall of the vagina may be pressed back and 
emptied, so that the body of the fetus engaging in the passage may 
