5i8 Veterinary Obstetrics 



However reliable this is as a sign that parturition is near, 

 it may become very misleading. We have previously stated that 

 sometimes during various stages of pregnancy the glands become 

 swollen and contain milk and that this may disappear and not be 

 seen again until at the close of pregnancy, weeks or months 

 later. 



Sometimes the milk glands become much enlarged and show 

 great functional activity long before parturition, so that in the 

 mare we have observed a profuse flow of milk escaping from the 

 glands for two or three weeks before the birth of the foal, though 

 everything seemed to be normal and parturition was regular. We 

 have also noted in previous chapters that we have at times ob- 

 served the secretion of milk by a mule during the estrual period. 



On the other hand, it sometimes occurs, especially in the mare, 

 that almost no milk is secreted prior to parturition and that the 

 glands are very slightly enlarged. Such is especially the case in 

 very old mares which have been bred for the first time. 



Fleming stiggests that this enlargement and increased func- 

 tional activity of the udder is due to the diversion to it of the 

 excess of blood from the uterus, which this organ no longer re- 

 quires. This explanation is not clear. The nutritive demands 

 of the fetus at the close of intra-uteriue life seem to be even 

 greater than at an earlier period. The fetus is larger and grow- 

 ing rapidly. The uterus must receive an increased amount of 

 nutriment, in order to perform its function of expulsion of the 

 fetus and placenta and repair of the injuries incident to parturi- 

 tion. It is rather a part of the general plan of nature in preparing 

 for the nutrition of the fetus after its birth. 



A very important sign of approaching parturition is the re- 

 laxation of the sacro-sciatic ligaments, which allows the muscles 

 passing over them to drop inward causing a sinking of the croup. 

 This relaxation increases the dilatability of the vulvo-vaginal 

 canal and makes it easier for the fetus to be propelled- through 

 it. The relaxation in these ligaments is thought by some to be 

 due to changes taking place within the ligament itself, consisting 

 largely of an effusion of lymph into it, which leads to its soften- 

 ing. Others refer the phenomenon to a change in the relationship 

 between the ossa innominata and the sacrum and coccyx. The 

 sacro-iliac ligaments, according to this view, become somewhat 

 relaxed, so that the articulation becomes less rigid and the 



