156 PRINCIPLES OF VETERINARY SCIENCE 



and to supply it with nutritive blood. The increase in size 

 affects chiefly the gravid horn (except in the case of twins) and 

 the body. The horn attains a length of 2j^ to 3 feet in the mare 

 and cow and a corresponding diameter. The uterus at this time 

 weighs about 9 pounds. 



The diagnosis of pregnancy in the mare is based on a clear 

 understanding of the anatomy and physiology of the genital 

 organs. As there always is danger of making mistakes, espe- 

 cially during the early stages of pregnancy, the veterinarian 

 usually makes a provisional diagnosis unless the signs are well 

 marked. 



Objective signs of pregnancy include all those changes that 

 are visible to or may be discovered by the examiner. During 

 the first weeks after conception there are few, if any, observable. 



The first sign that strongly suggests pregnancy is failure in the 

 occurrence of the estrual period. It is not an unfailing sign for 

 in some cases estrum recurs after conception has taken place. 

 Some pregnant mares will again receive the stallion. 



After the third or fourth month the mare shows a more thrifty 

 appearance, as a rule, by growing a sleeker coat and putting on 

 flesh. Not until the sixth month of the gestation period, or 

 later, is there an appreciable increase in the size of the abdomen. 

 About 25 per cent, of pregnant mares fail to exhibit this sign 

 until other more reliable signs are noticeable. 



An unfailing sign is the general enlargement of the udder. 

 This begins about six weeks before foaling time and is more no- 

 ticeable in the morning. By noon, if the mare has had exercise, 

 the swelling disappears. 



The secretion of colostrum and the formation of wax at the 

 teat orifices are other signs, but they do not occur until late in 

 the gestation period. When taken alone these changes of the 

 animal are not positively diagnostic and their absence does 

 not disprove pregnancy, yet they are more reliable than most 

 others. 



Movements of the fetal limbs and body are audible and pal- 

 pable after the mare has had a large draught of ice cold water. 

 They even may be seen by the eye after the seventh or eighth 

 month. To detect fetal movements the left ear should be placed 

 against the abdomen, just below the left flank and some eight 

 or ten inches in front of the stifle. When the hand is used, the 



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