Special Report on Diseases of Cattle Part 22

As abortion most frequently occurs at those three-week intervals at which the cow would have been in heat if nonpregnant, we may a.s.sume a predisposition at such times owing to a periodicity in the nervous system and functions. Poor condition, weakness, and a too watery state of the blood is often a predisposing cause. This in its turn may result from poor or insufficient feed, from the excessive drain upon the udder while bearing the calf, from the use of feed deficient in certain essential elements, like the nitrogenous const.i.tuents or alb.u.minoids, from chronic, wasting diseases, from roundworms or tapeworms in the bowels, from flat-worms (flukes, trematodes) in the liver, from worms in the lungs, from dark, damp, unhealthful buildings, etc. In some such cases the nourishment is so deficient that the fetus dies in the womb and is expelled in consequence.

Excessive loss of blood, attended as it usually is with shock, becomes a direct cause of abortion.

Acute inflammations of important organs are notorious causes of abortion, and in most contagious fevers (lung plague, rinderpest, foot-and-mouth disease) it is a common result. Affections of the chest which prevent due aeration of the blood induce contractions of the womb, as shown experimentally by Brown-Sequard. Pregnant women suffocated in smoke aborted in many cases. (Retoul.)

Ergoted gra.s.ses have long been known as a cause of widespread abortion in cows. The ergot is familiar as the dark purple or black, hard, spurlike growths which protrude from the seeds of the gra.s.ses at the period of their ripening. (Pl. V.) It is especially common, in damp localities and cloudy seasons on meadows shaded by trees and protected against the free sweep of the winds. The same is to a large extent true of s.m.u.t; hence, wet years have been often remarkable for the great prevalence of abortions. Abortions have greatly increased in New Zealand among cows since the introduction of rye gra.s.s, which is specially subject to ergot. As abortion is more prevalent in old dairying districts, the ergot may not be the sole cause in this instance.

The riding of one another by cows is attended by such severe muscular exertion, jars, jolts, mental excitement, and gravitation of the womb and abdominal organs backward that it may easily cause abortion in a predisposed animal.

Keeping in stalls that slope too much behind (more than 2 inches) acts in the same way, the compression from lying and the gravitation backward proving more than a predisposed cow can safely bear.

Deep gutters behind the stalls, into which one or both hind limbs slip unexpectedly, strain the loins and jar the body and womb most injuriously.

Slippery stalls in which the flooring boards are laid longitudinally in place of transversely, and on which there is no device to give a firm foothold, are almost equally dangerous. Driving on icy ground, or through a narrow doorway where the abdomen is liable to be jammed, are other common causes. Aborting cows often fail to expel the afterbirth, and if this remains hanging in a putrid condition it is most injurious to pregnant cows in the near vicinity. So with retained afterbirth in other cows after calving. That some cows kept in filthy stables or with slaughterhouses near by may become inured to the odors and escape the evil results is no disproof of the injurious effects so often seen in such cases.

The excitement, jarring, and jolting of a railroad journey often cause abortion, especially as the cow nears the period of calving, and the terror or injury of railway or other accidents proves incomparably worse.

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 pota.s.sium, 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, Zundel, and Youatt. In the early part of the eighteenth century British veterinarians recognized its contagiousness, but it remained for Franck (1876), Lehnert (1878), and Brauer (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, a.s.sisted 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 a.s.sume 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 a.s.sert 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 v.u.l.v.a, the infection traveling up the genital ca.n.a.l and directly infecting the uterus.

The belief long entertained that the female acquires the disease at the time of copulation as a result of transference of the infection from affected to healthy females on the genital organs of the bull has failed to receive the support of experimental evidence. The view that the disease is spread to any great degree in this way has been largely discredited. Cows of all ages are more or less susceptible, but young ones in first or second pregnancy most frequently abort. A second abortion is not unusual, and a third may occasionally occur, after which the cow usually becomes immune and thereafter carries her calf to maturity. Heifers from aborting mothers sometimes seem to be less susceptible than others.

_Symptoms._--Contagious abortion is a very insidious disease, developing very slowly through several months of the gestation period, and resulting finally in the expulsion of the immature young, this act being simply an indication of the presence of the disease and not the disease itself.

Because of this slow development and the fact that the health of the animal is not noticeably influenced, the presence of the disease may not be suspected until it has gained a firm foothold in the herd. The symptoms of approaching abortion are those preceding normal calving. In addition, there may be observed, a few days previous to abortion, a sticky, sometimes purulent, rusty, and odorless discharge. Abortion occurs most frequently from the third to the seventh month, according to the number of abortions, occurring early in first abortion, and later in each succeeding abortion until the calf is carried to full term and the mother has become immune. It happens frequently that calves are carried almost to full term, and are born alive, but are sickly, and soon die. Following abortion there is a dirty, yellowish-gray mucopurulent discharge which persists for two or more weeks. If abortion occurs early, the fetus is pa.s.sed surrounded by its membranes, but if late in the period of pregnancy, the membranes are retained, decomposition sets in and blood poisoning, which may cause the death of the animal, or sterility may result.

_Lesions._--The most characteristic change is found in the uterus where a dark-brown fluid, purulent or even gluey in consistency, and containing grayish-white flakes separates the material membranes from those of the fetus, preventing that intimate contact between the two which is so necessary for the interchange of fluids and gases by which the fetus is nourished and by which it obtains its oxygen. These being cut off, the fetus must of course die. The germs producing the disease are found in greatest numbers at this point. In addition there may be inflammatory changes, first in the walls of the uterus and then in the tissues of the fetus. These inflammatory changes seem most intense in the cotyledons and result in the destruction of the minute structure of those bodies, and they appear swollen, pale, and soft. The membrane of the uterus between the cotyledons also may show inflamed and necrotic patches.

_Complications._--Serious results sometimes follow abortion, and this is particularly the case when there is retained afterbirth. The retained membranes decompose, the poisonous products of decomposition and the organisms of decomposition themselves are absorbed, blood poisoning results, and the animal dies. Sometimes, when the animal is able to resist the effects of this decomposition, the uterus becomes the seat of such severe changes that sterility results. The walls of that organ become thickened and hard, the lining membranes become eroded, and conception can not take place. At other times the ovaries, where the reproductive cells originate, become affected and lose their function. Abortion does not invariably follow infection, but the calf is carried to full term. In these cases, however, retained afterbirth is a common occurrence, even to the extent that frequent retention of afterbirth in a herd may be taken as an indication of the presence of the disease. Very often suppurative processes persist for a long time, preventing conception, or sterility may result without apparent cause. A sterile cow is valueless, of course, for any purpose except for beef. Such animals are a source of infection for the others and should not be allowed to remain in the herd.

_Diagnosis._--The diagnosis of infectious abortion is made from the changes occurring in the fetal membranes and in the expelled fetus. This, however, is substantiated with certainty only by microscopic demonstration of the germ of abortion. The fact that repeated abortions are observed in a herd is also evidence of the presence of the disease. In consideration, however, of the fact that animals may be affected with the disease and disseminate the germs, even though they carry the fetus to full time, a diagnosis in such instances is only possible by laboratory methods. For this purpose the agglutination and also the complement-fixation tests are being used with splendid results, and by the aid of these biological tests it is possible to determine all infected animals in a herd. The tests are carried out with the serum from animals to be examined, only a teaspoonful of serum being necessary for the execution of both of these tests. It, however, has to be confined to laboratories which are properly equipped for such work.

_Treatment and prevention._--It may be said in general that treatment is without avail and all efforts should be directed toward prevention. Various medicinal agents, such as carbolic acid administered subcutaneously and methylene blue fed in large quant.i.ties, have been recommended, but have failed to stand the tests of scientific investigation and practical use.

Serums and vaccines have also been prepared and sold as cures and preventives, but the work is still considered in the experimental stage.

Bacterial vaccines are at present extensively used in the control of this disease, and while numerous reports indicate beneficial results from their administration, in other instances total failures have been recorded. It appears that the experiments in this line have not progressed sufficiently to justify definite conclusions.

The spread of the disease can be controlled to a great degree by the practice of sanitary measures directed toward the disinfection of premises and the isolation of animals at time of calving and aborting. For methods of disinfection of premises see page 363.

Make frequent observations of the animals of affected herds for symptoms of aborting, such as swelling of v.u.l.v.a or udder enlargement, and upon the discovery of an animal showing these symptoms place her immediately in a stall which is somewhat remote from healthy stock as a means of confining the products of abortion as much as possible should the act occur. If an animal aborts unexpectedly she should be removed to separate quarters and given proper attention as promptly as possible. The fetus, afterbirth, provided it has been expelled, and all litter that has been contaminated with them and uterine discharges should be gathered up and destroyed either by burning or burying. Clean and thoroughly disinfect the floor, gutters, and manger in the vicinity of the aborting animal.

Daily irrigations of the uterus with nonirritating antiseptic solutions, such as 0.5 per cent solution of cresol or compound solution of cresol, at body temperature have a tendency to prevent the multiplication of microorganisms in the uterus and in this way promote recovery. Douching of the uterus should be continued until the discharge ceases. In addition, the external genitals, root of the tail, escutcheon, etc., should be sponged daily with the antiseptic solution.

Aim to place all pregnant animals in disinfected individual pens or stalls a few days before they are expected to calve, and confine them to these quarters for three or four weeks following the delivery of the calf, or as long thereafter as uterine discharges are observed. Avoid carrying infection from the maternity stalls to other portions of stable, on shoes or otherwise. This may be prevented to some degree by the use of disinfectant solutions on shoes after the stalls have been entered or by wearing rubbers while in the maternity stalls, removing them after the isolated animals have been attended to. The isolation of cows at time of calving and the aborting animal is based upon the knowledge that the fetus, afterbirth, and uterine discharges of an affected animal at these times very frequently contain myriads of the abortion bacteria, and that unless these substances are confined and promptly destroyed an abundant opportunity is provided for the contamination of the food substances of the healthy animals and their contraction of the disease.

Refrain from breeding fresh cows for a period of six weeks to two months following calving. The aborting animal should be isolated for a period of six weeks to two months and under no consideration be permitted to mingle with the rest of the herd as long as uterine discharges are observed.

Douching of the external genitals of the bull, a practice formerly regarded as highly important for preventing the spread of the disease, is now recognized as being of doubtful value. The bull is protected from abortion infection to a great degree by permitting him to serve only such animals as have calved or aborted from six weeks to two months previously.

Investigational work has indicated that when the bull is affected with the disease the organs of his generative system commonly involved are not reached by the antiseptic solutions. A more rational method for the prevention of the spread of the disease by the bull consists in keeping him in an inclosure separate from the females and in having all services take place on neutral ground.

Great care should be used in purchasing cattle, and cows not known to be free from the disease should be kept in separate quarters until this point is determined.

GRANULAR VENEREAL DISEASE (INFECTIOUS GRANULAR VAGINITIS).

The affection to which the foregoing names have been given is a chronic, mild, and apparently contagious disease of cattle, characterized by an inflammatory condition of the mucous membrane of the v.a.g.i.n.a and the development of nodules upon its surface.

This disease is very widely spread, but from an economic point of view it does not appear to have great significance. Williams, who investigated it, a.s.serts that it is difficult to find a single herd in this country which is free of this disease. He considers it of great importance, claiming that granular vaginitis has a vital relation to abortion. This view, however, is not substantiated by other investigators, it being now generally accepted that the disease is only rarely responsible for abortion, and further, that it exerts no apparent ill effects on the health of the animal and that it has no effect on the milk yield.

_Symptoms._--Natural infection may take place either by direct contact of animals or at the time of service. Most of the cows in the affected herd contract the disease, but the bulls are rarely or very mildly affected. The inflamed condition of the membranes of the v.a.g.i.n.a results in a catarrhal exudate, and this discharge, which soils the external genitals and the tail, and the uneasiness and sometimes the straining of the animal, are the first and most prominent symptoms observed. Upon examination, small, hard, grayish nodules can be seen and felt upon the inflamed membranes. This acute stage may last for three or four weeks, then it gradually subsides and a.s.sumes the chronic form, only to flare up again as the animal comes in heat.

These nodules are sometimes found on the membranes of the uterus, and some investigators have argued from this fact that it was responsible for abortion and sterility. Others, however, deny this and point out that the bacillus of abortion can be demonstrated in nearly every case. The importance of the disease is therefore in dispute and the decision must be left to future investigation.

_Treatment._--The exaggerated importance which has been attached to this disease resulted in the exploitation of the most varied kinds of remedies for its treatment. It is true that with a protracted and laborious treatment it is possible to effect cures in from one to three months, but with our present knowledge of this disorder it is advisable to limit the treatment to animals which show an acute inflammatory condition of the v.a.g.i.n.a and v.u.l.v.a with a discharge as a result of the granular affection.

The treatment should be local and confined to the application of antiseptic washes in the form of irrigations. For this purpose a 0.5 per cent solution of the compound solution of cresol or of Lugol's solution has been found satisfactory.

PARTURITION (CALVING).

SYMPTOMS OF CALVING.

In the cow the premonitions of calving are the enlargement of the udder, which becomes firm and resistant to the touch, with more or less swelling in front, and yields a serous, milky fluid; the enlargement and swelling of the v.u.l.v.a, which discharges an abundant, stringy mucus; the drooping of the belly, and the falling in of the muscles at each side of the root of the tail, so as to leave deep hollows. When this last symptom is seen, calving may be counted on in 24 hours or in 2 or 3 days. When the act is imminent, the cow becomes uneasy, moves restlessly, leaves off eating, in the field leaves the herd, lies down and rises again as if in pain, s.h.i.+fts upon her hind feet, moves the tail, and may bellow or moan. When labor pains come on the back is arched, the croup drooped, the belly is drawn up, and straining is more or less violent and continuous. Meanwhile blood may have appeared on the v.u.l.v.a and tail, and soon the clear water bags protrude between the lips of the v.u.l.v.a. They increase rapidly, hanging down toward the hocks, and the fore or hind feet can be detected within them. With the rupture of the bags and escape of the waters the womb contracts on the solid, angular body of the fetus and is at once stimulated to more violent contractions, so that the work proceeds with redoubled energy to the complete expulsion.

This is why it is wrong to rupture the water bags if the presentation is normal, as they furnish a soft, uniform pressure for the preliminary dilation of the mouth of the womb and pa.s.sages, in antic.i.p.ation of the severe strain put upon them as the solid body of the calf pa.s.ses.

The cow often calves standing, in which case the navel string is broken as the calf falls to the ground. If, however, she is rec.u.mbent, this cord is torn through as she rises. The afterpains come on 3 or 4 hours later and expel the membranes, which should never be left longer than 24 hours.

NATURAL PRESENTATION.

When there is but one calf the natural presentation is that of the fore feet with the front of the hoofs and knees turned upward toward the tail of the dam and the nose lying between the knees. (Pl. XV.) If there are twins the natural position of the second is that of the hind feet, the heels and hocks turned upward toward the cow's tail. (Pl. XVIII, fig. 1.) In both of these natural positions the curvature of the body of the calf--the back arched upward--is the same with the curvature of the pa.s.sages, which descend anteriorly into the womb, ascend over the brim of the pelvis, and descend again toward the external opening (v.u.l.v.a). Any presentation differing from the above is abnormal.

OBSTACLES TO PARTURITION.