364 MATERNAL DYSTOKIA. 



Persistent Hymen. 



At page 29, we have described a wide duplicature of the lining mem- 

 brane of the vagina, which covers the meatus urinarius, and which looks 

 like, while it acts as, a valve (valvida vagince) to that opening. This 

 membrane, which stretches across the passage and separates the vulvular 

 from the vaginal canal, is the analogue of the hymen of woman ; and, as 

 in her, it may persist after the impregnation of primiparae — having escaped 

 rupture during coitus — and becoming abnormally rigid, may prove an 

 impediment to birth in some instances — though it must be confessed 

 they appear to be exceedingly rare. 



This cause of dystokia should be very much less frequently met with in 

 the equine and asinine species than other of the domesticated animals, in 

 consequence of the size and conformation of the male organ of copulation, 

 from which the membranous vaginal partition can scarcely escape rupture 

 when it is present, which is only occasionally.* With the bovine, caprine, 

 ovine, and porcine species, however, the case is different ; as the penis, 

 from its volume and shape, is far less likely to lacerate the hymen ; and 

 it is in the bovine species alone that the persistence of the latter at par- 

 turition has been found — at least so far as published observations show ; 

 and in all the instances the animals have been young and primiparae. 



It is just possible that in many animals of these species, the hymen 

 may be more or less intact until parturition sets in, when the foetus, in its 

 passage through the vagina, ruptures and effaces it without much delay 

 resulting, or other cause which might attract attention. 



But in others — few though they be — the membrane would appear to 

 offer a rather serious amount of resistance to the expulsion of the young 

 creature, and demand the services of the obstetrist. 



The cases recorded are exceedingly few, and none are to be found in 

 English Veterinary literature. 



I. On March 28, 1863, Mignon [Recueil de Med. Veterinaire, 1863, p. 767) attended a 

 two and a half years old Cow in an advanced stage of pregnancy, and which exhibited 

 all the signs of approaching delivery, with the exception of the labor pains, which were 

 not yet manifested. They however appeared on April ist, and continued for about 

 fifteen hours, but without any progress being made towards birth. On the 2d, Mignon 

 endeavored, by abdominal taxis, to assure himself if the calf was still alive, but this 

 failing he had recourse to vaginal exploration, when, to his surprise, his fingers met an 

 obstacle almost at the vulvular orifice. He was soon convinced that this obstacle was 

 nothing more than a wide band — a real duplicature of the mucous membrane — placed at 

 the entrance to the vagina, which it incompletely closed as a vertical septum, being 

 attached by its extremities to the walls of the canal. This vaginal band — a veritable 

 hymen — was flattened on both sides, wider at the ends than in the middle, and had 

 curved borders ; it measured two and a third inches in length, three-quarters of an inch 

 in depth at its extremities, but only about one-third inch at its central portion. The 

 calibre of the vagina was considerably diminished by this band ; the canal had two 



* The hymen appears to be only exceptionally present in the Mare, though it is an error to assume that 

 it is always absent- Not only is it sometimes to be found, and occasionally of large size and extraordinary 

 tenacity, but it may even become a source of trouble in unimpregnated Mares. Of this we have an 

 example by Mr. Thomson, of Beith {Veterinarian, vol. vii., p. 147). That Veterinarian was called to see 

 a young Mare, said to have inversion of the bladder. On his arrival, he saw protruding from the vulva a 

 membranous sac containing about a quart of fluid in its cavity. An examination proved the sac to be 

 a simple membrane, extremely vascular and much inflamed. It was easily pushed back into the vaginal 

 cavity, where it was found to be attached to the posterior part of the urethra and all around the vaginal 

 canal, so that the passage to the os uteri was completely obstructed ; the membrane could not be pushed 

 so far forward as the cei-vix. On romoving the hand, it again protruded whenever the Mare made an 

 effort. 



In another instance — a year and a half old Filly — Mr. Thomson observed an intact hymen, but there was 

 a small opening in it, immediately behind the urethra. 



