234 NORMAL PAllTURITION. 



mute, though anxious and uneasy ; while others, in addition to exliibit- 

 ing restlessness and distress, utter a half-stifled cry of pain. The Mare 

 whisks its tail, the Cow bellows, the Ewe bleats, the Bitch often whines, 

 and the Cat emits a low cry as if in suiifering. If the animal is at liberty, 

 it seeks a remote quiet place in which to bring forth its young ; while 

 some — such as the Bitch, Cat, Sow, and Kabbit — prepare a special nest. 



2. Dilatation of the Os Uteri. — The limit between this stage and the 

 former is not so well marked as our division would indicate. Neverthe- 

 less, it is meant to imply that the stage of dilatation of the os termi- 

 nates pregnancy and ends with complete extension in width of that 

 uterine passage. It is marked by increasing uneasiness of the animal : 

 pawing, lying down and rising frequently in a kind of aimless fashion, 

 while the expression of the physiognomy betrays suffering. When the 

 uterine contractions really commence, the creature suddenly stops, as if 

 surprised by the pain ; its eye looks animated and expresses anguish ; 

 the skin is hot, pulse quickened, visible mucous membranes injected ; 

 the abdominal walls are rigid and contracted, the flank is tense, and 

 very frequently faeces or urine are voided. During this pain, if the 

 cervix uteri is explored, it will be found that its attenuated border has a 

 tendency to become hard and prominent. When the pain has passed, 

 calm succeeds ; the cervix becomes thick and elastic, and the os is 

 markedly enlarged. Bach pain lasts for some seconds to two or three 

 minutes, the interval of quiet continuing to about fifteen minutes at 

 first ; though it diminishes when the contractions become more frequent, 

 more energetic, and more prolonged, and dilatation of the os progresses. 

 Then the fcetal membranes begin to be detached from the inner surface 

 of the uterus and enter the os, whence they pass into the vagina and 

 between the labia of the vulva, where they appear externally as the 

 *' water-bag." In the meantime, the fore limbs and the nose and head 

 of the foetus enter the os, and dilate it to its fullest extent, when the 

 cavity of the uterus forms a canal continuous with the vagina. 



3. Expulsion of tlie Foetus. — The pains become more severe, frequent, 

 and sustained, and to the uterine contractions are added those of the 

 diaphragm, and abdominal and other muscles. If the animal is stand- 

 ing, it brings all its limbs under the body, arches the back, elevates the 

 tail, slightly flexes the hocks, makes a deep inspiration, closes the glottis 

 to imprison the air in the chest, and by a powerful contraction of all the 

 muscles of the trunk, it brings such an amount of pressure to bear on 

 the foetus as to propel it into the pelvic cavity and rupture the chorion. 

 At each contraction the "water-bag" — formed by the allantois and 

 amnion — protruded beyond the vulva, increases in volume. It varies 

 in different animals ; being in the Cow about as large as the bladder of 

 a Pig, and in the Bitch the size of the carp's swimming bladder. When 

 it is very large in advanced parturition, it is reckoned a good sign ; 

 though it may not indicate a good presentation of the foetus, nor yet an 

 easy birth. 



The water-bag soon ruptures, and its contents partly escape — that 

 behind the thorax of the foetus being i-etained, and voided only in small 

 quantity as the uterus contracts. When the membranes are thinner 

 and weaker than usual, they may rupture before the os is completely 

 dilated, and then the fluid escapes in a small quantity at a time ; this 

 frequently happens with primiparae, though it is sometimes observed in 

 protracted labour, which is the most painful. In general, however, no 

 harm results from this premature rupture if parturition is not too long 



