Chapter XVII: Front Matter (17)

_Impaction of the rumen or manifolds_, and _obstinate constipation_ with the resulting straining or compression must be named as an accessory cause.

Severe _constitutional diseases_, especially the infectious fevers, _aphthous fever_, _lung plague_, _rinderpest_, etc., are occasional causes of abortion.

It may be brought about by direct irritation of the womb, as in _ovariotomy_ or _dilatation of the cervix_, or again by _death of the fœtus_ through _twisting of the umbilical cord_.

Where cattle are subjected to dry winter feeding, in the absence of ensilage or roots, on the magnesian limestones, small _calculi in the kidney_ are almost the rule in winter and the irritation caused by these conduces to abortion.

Nor must mental influence be altogether ignored. Cows and even mares are exceedingly sensitive to the smells of _decomposing animal matter_, as seen every day in the vicinity of _abattoirs_, or in case the _carcass_ of one of their fellows has been opened, and not infrequently in connection with _carrion_, and the occurrence of abortions after such excitement has been frequently noticed. Cases are on record of specially susceptible cows having had active labor pains, from being with another cow at the time of parturition. Shepherds have noticed that violent thunder storms have been followed by numerous abortions in the flocks.

_The Contagious Form._ Any of the usual causes of sporadic or accidental abortion may coöperate with the true infectious element and give unusual energy to it, yet it is of the utmost importance to recognize the contagion as the essential cause in all cases in which it is present. This can usually be done by a careful inquiry into the history of the outbreak.

When a herd has been continuously healthy up to the date of the introduction of a cow brought from a herd where abortion has been prevailing, and when following her arrival, one after another of the original members of the herd abort, without any apparent cause in the way of change of feed, water, barn, stalls, or general management, the evidence of the introduction of contagion by the cow in question is very circumstantial and forcible. If pregnant cows standing next to the new cow, or near to her, abort, the argument for contagion is still further corroborated. If the trouble continues in the herd year after year, attacking fresh animals some months after their purchase, the case becomes still stronger.

Or if a cow from a healthy herd is sent to a bull, that has been allowed to serve an aborting cow, and if the resulting pregnancy in the first cow is terminated by abortion, and if this is followed by successive abortions in the previously healthy herd, we may reasonably conclude that we are dealing with the infectious form. If no other appreciable cause for the trouble can be found we may reasonably conclude that this was the channel for infection.

Or a bull is brought from a herd where abortions have taken place, and some time after his arrival, the cows of the previously sound herd begin to abort, the first cases being in those that the new bull has served. The occurrence is manifestly the result of contagion.

Or a newly purchased cow aborts, and is disposed of in consequence, and another cow, placed in the same stall, in due time aborts also, and others follow in succession, especially those that stood next or near to the stall in question. Everything points to an introduced infection.

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.

Nygaard reports that a bull from a healthy herd, but which had been allowed to serve some cows from a neighboring infected herd, was sold to go on a previously healthy farm, where he was put to 14 cows only. Of these 12 aborted, and the complement of the herd, beyond the 14 cows, put to another bull, remained well.

In each of these cases the environment of the animals and the conditions remained the same, the one appreciable cause of the outbreak being the contact with an animal from an aborting herd.

_Experimental Infection._ Braüer led the way by transferring in 11 instances the vaginal mucus of aborting cows to the vagina of healthy ones. The resulting abortions occurred from the 9th to the 21st day after inoculation. Lehnert repeated this on two cows, the abortions taking place on the twelfth and twentieth days respectively. Trinchera transferred the purulent vaginal mucus of an aborting cow to the vaginæ of healthy ones, determining in the latter, in 9 to 13 days, abortion attended by suppurating vaginal catarrh. He secured similar results by using the material scraped from the surface of the chorion of an immature fœtus.

The Scottish Commission (Woodhead, McFadyean and Aitkin) placed a healthy pregnant cow in an aborting herd, and on two successive days lodged in her vagina for twenty minutes a piece of cotton wool soaked in the vaginal mucus of a recently aborted cow. Within a month abortion threatened, and on the seventieth day a seven months calf was dropped.

In a second experiment a cow, six months in calf, was taken from a healthy herd and placed in an aborting dairy herd and a quantity of vaginal mucus from a cow that had recently aborted was injected under the skin of the vagina. She calved prematurely at the end of the eighth month of gestation.

Williamsen, while treating a herd for abortion, took a piece of the afterbirth of one of the aborting cows and rubbed it on the vagina of a healthy cow of his own, which had a habit of carrying her calf fourteen days over time. Five days after she had premature parturition.

He took a fragment of the fœtal membrane from the cow just named and rubbed it on the vagina of a pregnant cow condemned for tuberculosis. In seventeen days the cow aborted.

Though not started as an experiment, the writer may name the general extension of abortion from one or two cows in a tuberculous herd after they had been tested with tuberculin. Cases of this kind are doubtless much more common than has been supposed.

Kilborne and Smith developed suppurating vaginal catarrh in cows and mares by inoculating them with the artificial cultures of bacilli obtained from the vaginal secretions of aborting mares.

Turner made cultures from the ovaries of aborting mares, and others from the genital organs of foals suffering from omphalitis, and produced abortions in pregnant mares by injecting with the same.

_Pathology._ _Bacteriology._ Franck attributed the disease to _leptothrix vaginalis_, but subsequent observers failed to substantiate this.

The Scottish Abortion Commission isolated five different bacteria from the abortion membranes and vaginal mucus, but failed to identify any one of these as, by itself, capable of causing the disease.

Nocard found in the fibrino-purulent matter between the chorion and womb in aborting animals a micrococcus occurring singly or in chains, and a short, delicate bacillus isolated or in pairs. From the absence of evil effects between pregnancies he opines that the germs grow in the membranes only, and do not affect the womb nor the general system. He recognizes, however, that they survive in the womb from one pregnancy to another in the complete absence of these membranes.

Galtier, on the contrary, conveyed the disease variously by the inoculation or feeding of the milk or abortion membranes to sheep, goat, pig, rabbit and Guinea pig, and accordingly claims that the general system of the pregnant animal is infected, and that the germs can be conveyed through the blood to the womb. In deducing this from feeding experiments he appears to make too little account of the ready infection through proximity of the anus and vulva.

Chester, of Delaware Agri. Experiment Station, found in the fœtal membranes of aborting cows a bacillus, which in form and habits of growth closely resembled the bacillus coli commune. In the fermentation test, however, it showed a marked difference.

Inoculated on rabbits it did not prove fatal. Injected into the vagina of a healthy pregnant cow it caused slight catarrhal discharge for four or five days, but the calf was carried to full time six and a half months later.

Bang found in aborting cows, between the womb and fœtal membranes, a considerable odorless, gelatinoid, liquid exudate, and some pus cells. There was active catarrh of the uterine mucosa which often carried the disease over into the next pregnancy. In the exudate he found a number of very minute nonmotile bacilli (1 to 3μ), which stained readily with aniline colors, excepting in a vacuole or nucleus which was less deeply pigmented. This bacillus grew well in serum glycerine bouillon, and more sparingly in serum-gelatine agar. In the latter it showed a remarkable peculiarity which serves to identify it readily from other microbes, in two successive zones of luxuriant growth at two different depths, with an intermediate clear zone, in which little or no growth took place. It seems to prefer a greater or lesser supply of oxygen (21 or 90:100) without being able to adapt itself to the intermediate condition. As already stated it produced abortion in the cow in 21 days after injection into the vagina. It also induced uterine catarrh and abortion in ewes, goats, rabbits, Guinea pigs and mares when injected into the vagina. From the vagina it usually reaches the womb, but not always. In several cases in which it was injected subcutem or intravenously it caused hyperthermia, and was later found in abundance in the interior of the womb and fœtal membranes, and in the bowels of the fœtus. The microbe is, therefore, capable of living in the blood and affecting the womb by whatever channel it may enter the system.