PRETENTION OF THE AFTERBIRTH 327 



tions of the uterus are unable to sever the connective tissue 

 adhesions of the placentae thus formed. Firm union of the 

 placentas is also found in abortion at the seventh or eighth 

 month of pregnancy. The union here is not always connective 

 tissue ; in fact, pathological changes in the placentas fcetales 

 prevent separation. 



A portion of the afterbirth may also be caught in the 

 empty horn. This happens when the uterine contractions are 

 very violent. A part of the membranes, especially a piece of 

 the chorion, lies in the empty horn, where it has become united 

 to the cotyledons. When the muscularis of the gravid horn 

 contracts and the secundines are separated, their weight is 

 sufficient to cause detachment of the foetal membranes in the 

 empty horn. It may happen, when the uterine contractions 

 are violent, that the slit-like opening leading into the unimpreg- 

 nated horn becomes so narrow as to interfere with the expul- 

 sion of the secundines lying within it. At the same time the 

 balance of the afterbirth is also kept back. 



A closed cervix prevents expulsion of the foetal envelopes 

 within the uterus. This is a frequent cause of retentio secun- 

 dinarum. The membranes are separated but cannot be ex- 

 pelled ; it is often seen in cows with pendulous bellies. Here 

 the process of involution is so slow that the cervical canal 

 begins to close before the uterus has fully contracted. 



Symptoms. — The secundines may be partly separated and 

 hang from the vulva ; but it is possible that nothing is visible. 

 Such animals mostly show but few symptoms, if any, during 

 the first three days ; nevertheless a disturbance may be notice- 

 able previous to parturition (see " inversio uteri "). After three 

 to five days that part of the secundines exposed to the air 

 begins to decompose. This is not necessarily followed by a 

 disturbed general health. It frequently happens that such 

 cows are apparently healthy, only the lacteal secretion remains 

 limited. 



Now and then straining is seen — that is, abdominal pres- 

 sure supports the uterine contractions and attempts at micturi- 

 tion. When a large amount of the secundines project from the 



