DISEASES OF DOMESTIC ANIilALS. 193 



PAKTURITION. 



The Membranes that enclose the Foetns before Birth.— The ex- 



ternal is the chorion ; the internal is the amnion, and between these 

 two we have the alantois, which is a kind of serous membrane, and 

 presents two portions — one in connection with the amnion, and the 

 other with the chorion. It contains the amoniotic fluid. It serves 

 to keep the foetus warm, and to protect the foetus and the mother ; 

 and in connection with the foetus, at an early period, there is what 

 is called the umbilical vessel, which, at birth, is hard to detect. 

 Then we have the placenta, by which the blood vessels of the foetus 

 and those of the mother are brought into close contact ; yet they do 

 not anastamose, but the changes take place in the blood by osmotic 

 influence. Then there is umbilical cord, which is formed of the two 

 umbilical or hypogastric arteries and the umbilical vein, covered by 

 a gelatinous matter. Then there is the urachus, which is in con- 

 nection with the bladder, and in after-life forms a ligament for the 

 bladder. The placenta in the mare is attached by villi. In the cow 

 it is attached by cotyledons, which are about sixty or seventy in num- 

 ber. The capillaries of the foetus and uterus come in close contact, 

 and so form these villi and cotyledons. They are little tufts attached 

 to the uterus. The period of gestation varies in different animals. In 

 the mare it is eleven months, in the cow nine months, in the ewe five 

 months, in the bitch sixty-three days, in the sow one hundred and 

 twenty to one hundred and forty days. But a mare may go even a 

 month longer than the time ; and a case is recorded where a filly had 

 a fold at twenty-two months old, and heifers at fourteen months old; 

 and a case is recorded of a mare having a foal at thirty years old. 

 Mares moderately kept and worked will breed longer than one kept in 

 opposite manner. Difference of temperature is also supposed to have 

 an influence. We are sometimes called to tell whether a mare or a 

 cow is pregnant or not, and a correct opinion can sometimes be given, 

 and in other cases a mistake is easily made. A mare generally be- 

 comes quieter in disposition, thrives better, and, after a certain period, 

 the belly becomes distended, and some mares may go eight or nine 

 months without showing this much. There are various ways recom- 

 mended to determine this. The stethoscope is recommended, by 

 which you can hear the foetal heart beat ; but you will be very liable 

 to make a mistake in this way. Another is to insert the hand into 

 the vagina and find out the condition of the os-uteri. But the best 

 way is to examine per rectum, and in any case where it is necessary to 

 give a definite opinion, examine in this way. As to the manner in 

 which a mare should be used during pregnancy, there is difference of 

 opinion. Keeping her in her natural condition is perhaps the best, 

 but it is necessary sometimes to work her, and so long as Mforked mod- 

 erately and not put to the waggon or cart, nor backed violently, there 

 is no great danger. Such is the case with farm mares, and parturition 

 is easier with them than those kept in the stable. There are certain 

 signs of immediate parturition ; the sacro-sceatic ligament changes to 

 a certain extent, and there is milk secreted; and when a wax appears 

 on the teat, parturition generally occurs in two or three days, and 

 often in twenty-four hours, and the water bag appears. The mare 

 usually lies down, but the cow sometimes stands during parturition. 

 It is sometimes best to be present to ligature the artery. Tie it about 

 an inch from the umbilical opening, and cut off about an inch from 

 the ligature. The natural presentation of the 'foetus is the fore feet 



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