An indefinite number of other exemplary cases might be adduced, each varying from the last, but all agreeing in this, that the evidence of infection stands out prominently and unmistakably. The infecting material may have been carried by the tail, tongue, soiled stall, gutter, rubbing post, fence or other object, yet the fact of contagion can be demonstrated with reasonable certainty.
These conclusions have been repeatedly affirmed by actual experimental transmission. The Scottish abortion committee found that healthy pregnant cows often escape, though standing near or even next to an aborting one, but that when a piece of cotton wool was inserted into the vagina of an aborting cow for twenty minutes and then transferred to that of a healthy one, the latter invariably aborted. Galtier found that when the infecting vaginal mucus of the aborting cow was transferred to the same passage of the healthy pregnant one, abortion took place in the latter. He succeeded in conveying the disease in this way from cow to sow, ewe, goat, rabbit and Guinea pig, and found that growth in the body of the rodent intensified its virulence, so that it could then be successfully inoculated on the mare, bitch and cat.
Bang subjected two cows, from healthy herds and three months pregnant, to repeated injections of the products of the culture of his abortion bacillus in serum glycerine bouillon. Three injections were made on April 14, May 23 and June 4, and on June 24 one cow aborted. The other sickened and when killed was found to carry a dead fœtus. Pure cultures of the abortion bacillus were found in the fœtal membranes and liquids of both animals.
Casual Infections. In a case which came under the observation of the present writer, a family cow kept in a barn where no abortion had previously occurred, was taken for service to a bull in a herd where abortion was prevailing, and though she was only present at the latter place for a few minutes, she aborted in the sixth month.
Another cow from the same aborting herd, was taken into another herd at a distance of two miles, where abortion had been unknown up to that time, and some months later the cow standing in the stall next to her aborted. The remainder of this herd was sold soon after, so that the further progress of the disease was not traced.
Tobiassen quotes the case of a cow from an aborting herd, which calved a fortnight before the regular time. The calf was at once sent to another farm where no abortion had occurred, and placed in the same building with the pregnant cows, all of which later aborted. The outbreak thus started lasted for several years.
Jansen as quoted by Sand, reports the case of a cow from an aborting herd having been taken into a herd that had been previously quite free from the disease. Soon after her arrival she aborted, and later, cows in the same herd aborted. The owner kept the matter secret and sent his cows to a neighbor’s bull for service, with the result that for two years abortion prevailed among the cows served by this bull.
J. R. Jansen reports that a cow brought from an infected farm, for fattening purposes, proved to be pregnant and finally aborted, and that 24 of the pregnant cows on the same farm aborted in the same year.
Mörck relates how a cow that had aborted a fortnight previously was taken to a farm where abortions had never been known. She aborted during her next gestation and so did the rest of the herd, 9 in number.
Christensen records the occurrence of a general abortion in a previously healthy herd, members of which had been sent for service to the bull of a neighboring aborting herd.