All irritant poisons cause abortions by the disorder and inflammation of the digestive organs, and if such agents act also on the kidneys or womb, the effect is materially enhanced. Powerful purgatives or diuretics should never be administered to the pregnant cow.
Among other causes of abortion must be named the death or the various illnesses of the fetus, which are about as numerous as those of the adult; the slipping of a young fetus through a loop in the navel string so as to tie a knot which will tighten later and interrupt the flow of blood with fatal effect, and the twisting of the navel string by the turning of the fetus until little or no blood can flow through the contorted cord. There is in addition a series of diseases of the mucous membrane of the womb, and of the fetal membranes (inflammation, effusion of blood, detachment of the membranes from the womb, fatty or other degenerations, etc.), which interfere with the supply of blood to the fetus or change its quality so that death is the natural result, followed by abortion.
Treatment.—Although the first symptoms of abortion have appeared, it does not follow that it will go on to completion. So long as the fetus has not perished, if the waters have not been discharged, nor the water bags presented, attempts should be made to check its progress. Every appreciable and removable cause should be done away with, the cow should be placed in a quiet stall alone, and agents given to check the excitement of the labor pains. Laudanum in doses of 1 ounce for a small cow or 2 ounces for a large one should be promptly administered, and repeated in three or four hours should the labor pains recur. This may be kept up for days or even weeks if necessary, though that is rarely required, as the trouble either subsides or abortion occurs. If the laudanum seems to lack permanency of action, use bromid of potassium, or, better, extract of Viburnum prunifolium (black haw), 40 grains, at intervals of two or three hours until five or six doses have been given.
CONTAGIOUS ABORTION.
Contagious abortion (also known as epizootic abortion, enzootic abortion, and slinking of calves) is a disease affecting chiefly cattle and to a lesser degree other domestic animals, and characterized by an inflammatory condition of the female reproductive organs, which results in the expulsion of the immature young.
History.—This disease has been known in England and continental Europe for many years, and descriptions of it are mentioned in the writings of Mascal, Lafoose, Skellet, Lawrence, St. Cyr, Zündel, and Youatt. In the early part of the eighteenth century British veterinarians recognized its contagiousness, but it remained for Franck (1876), Lehnert (1878), and Bräuer (1880) to produce the disease in healthy, pregnant cows by the introduction of exudate and material from aborting animals. Nocard (1888) isolated from the exudate between the mucous membrane of the uterus and fetal membranes a micrococcus and a short bacillus which were found continually in contagious abortion, but he failed to reproduce the disease by inoculations of pure cultures of these organisms into healthy, pregnant animals. In 1897 Bang, assisted by Stribolt, published their findings regarding infectious abortion of cattle, in which they incriminated Bang's bacillus of abortion as the causative agent. With pure cultures of this bacillus they were able to produce the disease artificially and to recover the same organism from the experimental cases. Since that time many noted investigators, both in this country and in Europe, have confirmed these findings.
Cause.—The Bacterium abortus of Bang is now generally recognized as the causative agent of the disease of cattle. Formerly it was thought that abortion was due to injury, such as blows, horn thrusts, falls, etc., or the eating of spoiled feed and certain plants, and while this may be true in a limited number of cases, careful investigations have demonstrated these claims to be largely unfounded. It is now generally recognized that when abortion occurs in herds from time to time, it is safe to assume that the disorder is of an infectious nature and should be so treated.
Natural mode of infection.—This phase of the disease is of greatest importance for a clear understanding of the methods of prevention. Many investigators have demonstrated that the infection is transmitted through the digestive tract, through contaminated feed and water. The germs are taken up by the body from the intestines with the liquid nourishment, reach the blood, and are carried to the genital organs, where they find conditions best suited to their development. Some assert that calves are infected in this manner by suckling infected mothers, the germs being present in the milk, or the teats having been contaminated by coming in contact with infective discharges. It is claimed that infection contracted in this manner remains dormant in the body of the calf until pregnancy begins, and then the organism, finding conditions suitable for its development, produces the disease.
Abortion may occasionally be transmitted from cow to cow by direct contact. The discharges from diseased cows, swarming with the germs, soil the external genitals, tail, and hind quarters, and then a susceptible animal, by contact, gets the infective material upon the vulva, the infection traveling up the genital canal and directly infecting the uterus.