Many forms of genital malformation occur, but only those which produce sterility are pathologically important.
One alone causes very marked disturbance, viz., imperforate vagina. This condition may be accidental or acquired, and may follow either difficult parturition, with circular lesions of the vagina, or burns or cauterisation of the vagina, followed by adhesion of its walls.
It is generally of congenital origin, and the obstruction as a rule is in the region of the hymen, as a consequence of some anomaly in development, and not of abnormal development of the hymen itself.
This imperforate condition of the vagina is not attended by grave consequences during early life; but later, when the generative functions become active, all the products of secretion of the uterine and vaginal mucous membranes accumulate in the closed cavity, giving rise first to muco-metritis, then to muco-kolpitis, similar in its development to the hæmato-kolpitis of young girls. The uterus gradually becomes distended with liquid, the neck is dilated, and a portion of the vagina may attain enormous dimensions, so much so as to suggest pregnancy.
Symptoms. The symptoms become appreciable only after a time—about one year or fifteen months in heifers—and they seem to be associated with the appearance of œstrum. The animals make continued expulsive efforts, which when the genital canal is much distended may become extremely violent. There is also dysuria as a consequence of compression, together with uterine and vesical colic, loss of appetite and wasting.
Diagnosis. The diagnosis requires care, and can only be arrived at after examination of the vagina and examination per rectum. In young females this examination is extremely difficult, because of the narrowness of the genital tract and of the rectum. For vaginal examination we prefer to use a small speculum, which exposes the depths of the vagina or the transverse septum without necessitating other manipulation. On rectal examination the uterus and vagina are sometimes found to be enormously enlarged, and to contain a quantity of fluid, but no fœtus.
Fig. 235.—Imperforate vagina: position and appearance of the genital organs. Cu Distended uterine horns (muco-metritis); Va, dilated extremity of the vagina; Ve, bladder, distended with urine, owing to compression of the urethra. The hymen was situated about 1¼ to 1½ inches in front of the meatus urinarius.
Prognosis. The prognosis is grave. Unless treatment is undertaken the animals die in consequence of exhaustion or secondary peritonitis.
The treatment is simple, and consists in aseptic puncture of the septum and evacuation of the contents. The operation is carried out with a long, large-sized trocar, which is passed through the centre of the most prominent portion of the transverse septum where it projects towards the vulva. Five, ten, or fifteen quarts of mucous fluid escape, and the constitutional disturbance disappears almost instantly.