OTHER CAUSES OF MATEJLXJL JJYSTOKIA. ^69 



3. Stkictuke ok Occlusion of the Uterus by External Bands 



OR Mkmhuanes. 



A number of writers, especially in foreign periodicals, have described 

 the pi'esence of bands or membranes external to the uterus — either in 

 the peritoneal cavity or vagina — obstructing the passage of the ftctus 

 and rendering birth almost, if not quite, impossible without an operation. 



With regard to the treatment of these cases, but little can be said. 

 When the bands are in the vagina, their division is the principal object, 

 after which, if no other obstacle is present, delivery can take place. 

 When, however, the uterus is constricted by an external abdominal 

 band — though this condition will be ditlicult to diagnose — then probably 

 no course can promise anything like a successful result except the 

 Ciesarian section. 



4. Persistent Hymen. 



At p. 30 there was 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 {valvula vaijiiue) to that opening. 

 This membrane, which stretches across the passage and separates the 

 vulvar from the vaginal canal, is the analogue of the hymen of woman; 

 and, as in her, it may persist after the impregnation of piimiparas — 

 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 parturition has been found — at least so 

 far as published observations show ; and in all the instances the 

 animals have been young and primipane. 



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 any other cause which might attract attention. 



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



^ The hymen appears to be only exceptionally present io the Mare, though it is an 

 error to assume tli.'it it is always absent. Not only is it sometimes to be found, and 

 occasionally of large size and extr.iordinary tenacity, t)ut it may even become a source of 

 trouble in uniniprejjnated Mares. Of this we have an example by Mr. Thomson, of 

 Belch ( yeleriiiarian, vol. vii., p. 147). That veterinarian was called to see a young 

 Mare, said t<"i have inversion of the bladder. On his arrival, he saw protruding from 

 the vulva a membranous sac containing about a quart of Huid in its cavity. An exami- 

 nation proved the s.ac to be a simple membrane, extremely vascular and miich inflamed. 

 It was easily pushed hack into the vaginal cavity, wh^re it was found to be attached to 

 the posterior part of the urethra and all around the vaginal canal, so that the paHsage to 

 the OS uteri w.-va completely obstructed ; the membrane could not be pushed so far 

 forward as the cervix. On removing 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. 



24 



