42 VETERINARY OBSTETRICS. 
enlargement becoming gradually more marked until 
the period of parturition. About two weeks before 
parturition, in both these animals, a mucous discharge 
makes its appearance from the inferior commissure of 
the vulva, and at the same time the lateral aspect of 
the croup begins to fall, owing to relaxation of 
the pelvic ligaments. This condition is known as 
“slipping,” or “loosening.” When all these conditions. 
are present, the animal has arrived at the termination 
of the period of gestation, and the more immediate 
symptoms of parturition commence. The animal 
becomes restless, continually on the move from one 
hind foot to the other, lying down occasionally; and. 
the Mare, especially if she has a hot temper, behaves. 
much in the same way as shown in colic. The pulse, 
if felt in this condition, is quick, frequent, and irritable, 
and the mucous membrane of the eye may be injected. 
The uterine contractions now commence, the animal at. 
this period apparently suffering an amount of pain. 
Each contraction may be accompanied by a groan, and. 
last only for a few seconds. The interval between 
the contractions may be, at the primary stage of 
parturition, from five to ten minutes. The contractions. 
now become more powerful and of longer duration, 
the interval between being shorter. The ‘os uteri” 
becomes dilated, the uterine contractions having forced. 
the foetal membranes through that opening. Shortly 
afterwards, the amniotic sac appears at the margin of 
the vulva, containing the ‘liquor amnii.” This sac is. 
sometimes called the “water bag,” sometimes the ‘‘sac 
containing the fluids.” The sac may rupture in the. 
