CONTAGIOUS ABORTION IN DAIRY CATTLE

Manawatu Times, Volume LIV, Issue 6918, 25 May 1929, Page 4

CONTAGIOUS ABORTION IN DAIRY CATTLE

Essential Control Measures Outlined

BY THE DEPARTMENT OF AGRICULTURE

By tlic Department of Agriculture. Among the diseases of stock there arc several which are met with commonly in. almost every country where extensive farming operations arc pursued. It appears to be the usual sequence of intensive farming practice that diseases of stock arc more numerous and perhaps more acute than in countries where animals are allowed more freedom, and where farming might bn described as extensive. Such a condition is more or less expected when one considers that dairy cows under intensive dairying systems are subject to the strain of regular annual breeding and regular and increasing production of milk annually. By selective breeding the modern high yielding dairy cow luis been aptly described as a veritable milking machine. Therefore, if both the breeding and the milking properties are to bo maintained in our dairy herds, increasing demands will continue in regard to the careful feeding and management _ of dairy stock in order to prevent either a break in the continuity of breeding or a derangement of the milking apparatus, the mammary gland. So elaborate and so highly developed has the modern cow become that diseases of the mammary gland and those associated with breeding arc assuming far greater economic importance. Mammitis was referred to somo time ago in these notes and farmers were advised through the department's Journal of Agriculture and through the press as regards the prevention of this trouble. This advice is now available in a bulletin .which can be obtained free by all owners on application to any office of the department. Contagious abortion in dairy cows iu tlio Dominion, resulting as it does in the loss of calves and loss of milk supply, is such that the disease requires the most careful attention and care by all owners of cattle. It is only by studying the nature of the disease that proper and effective measures can be taken to control and prevent the spread throughout a herd. There is also the serious factor of sterility and loss of breeding as a sequel to the disease which requires careful consideration. Probably contagious abortion is a more common factor than any other in causing permanent sterility in cows, as distinct from the conditions of tern porary sterility which so frequently occurs here.

The discaso is a very insidious one, and may be present in a licrd for some weeks or months before an actual abortion takes place, which act is the only outward sign the farmer has that something is amiss. The disease is due to a specific organism, Bang’s bacillus, which inadcs the womb of the nant animal, setting up a chronic inflammation between the membranes and the wall of the womb. Later the blood supply of the developing foetus is cut off by this inflammation; the foetus acts as a foreign body and the stimulus is given for the act of abortion and the calf is bora prematurely. All pregnant bov.incs are liable to infection, but probablv first calving heifers are more susceptible, as they have not previously had an opportunity of developing any immunity to the organism. _ Once an animal has aborted, a certain degree of immunity is developed, which may not, however, be sufficient to enable the animal to remain pregnant throughout the full period of a second pregnancy. Invariably, however, the infected animal will carry her third calf the full period. At each and all of these births the cow is a possible source of contamination of pasture through the discharges which come away at parturition. At the time of abortion there is generally a profuse discharge of a yellowish chocolate coloured nature which is most dangerous from au infective viewpoint. As infection occurs in the majority of cases through ingestion of food or water contaminated by the discharge from a previous case of the disease, the necessity of detecting a recently aborted cow, isolating such an animal in a paddock by hcrseli, effectively dealing with all discharges by burning, burying, or spreading them over with freshly burnt lime, keeping the animal isolated from the herd until all discharge has ceased, washing the vaginal passage and the womb itselc (when possible) at regular intervals while the discharge lasts, washing the external genitals and tail with weak antiseptic solutions at regular intervals and taking all-other known precautions to prevent contamination of the remainder of the herd, at once becomes apparent. It is true that occasionally abortion of a sporadic nature, and not duo to the abovo organism, does occur. Such cases result as a rule from an injury, a fall on rough country, excessive dogging and trucking, dietetic causes sucli as frosted roots and fermented foodstuffs likely to cause severe indigestion and “bloating.” It is much safer in dealing with this disease to treat every case as contagious and adopt preventive measures until tuo cause is proved otherwise. Iu the detection of this disease the farmer himself or a reliable deputy should carefully examine his herd twice daily at each milking time. In this way any animal suspected of early or premature calving, as shown by the appearance of tlie external genitals, can ha isolated from the herd. A small isolation paddock close to the homestead is absolutely essential for this purpose; such a paddock cuu bo used

for calves if not otherwise required. When abortion has taken place there is a tendency for retention of the foetal membranes. Such retention is likely to causo a chronic inflammation of the womb through the invasion of secondary organisms, which is undoubtedly a common cause of sterility afterwards. This being so, certain measures, such as the careful removal by hand with frequent flooding and washing out of the womb with weak antiseptics at regular intervals, are recommended.

As curative measures are not satisfactory, and as vaccination against the disease in unsatisfactory in bringing about immunity against an attack, owners are advised to uso all their powers of observation in the early detection of the disease, and to take every possible precaution to prevent its entry and spread in a herd. The method of control of the disease, which in the present state of world knowledge offers more hope of success than any other, is the building up of an abortion-free herd in the case of an already badly infected berd, and in the case of a slightly infected herd, the elimination of all reactors. In regard to this disease, more than any other, the farmer should provide his own young stock by rearing bis own heifers, and thus prevent the introduction of the disease from outside sources. When getting Tid of animals which have aborted, the works should bo availed of, as if those animals pass through the saleyards ah unsuspecting buyer may thus introduce the discaso to his herd.

There is probably no disease in which careful management and regular attention by tho owner is better repaid. The bull may transmit the disease from an infected animal to a clean animal through actual physical contact or through service. Tne bull may even harbour the organism in bis genital organs. By far the commonest method of infection in cows is, however, by ingestion of contaminated food or water.

In the diagnosis of the extent of the disease in any herd a physical examination of the herd is not of much assistance. A laboratory test known as tho agglutination test is quite dependable, and to enable this to be carried out samples of blood taken under conditions which prevent contamination aro necessary. The veterinary laboratory at Wailaceville tests hundreds of samples of blood for owners annually and gives them the true percentage of the disease in their herds. After abortion has taken place itfrequently happens that such animals appear in season very soon afterwards. On no account should these animals bo allowed to the bull until at least six weeks or two months after all discharge has ceased. To effect this it is absolutely essential that tho bull should be kept under control and not allowed to mix with tho herd.

The following control measures aro absolutely essential in combating the ravages of contagious abortion: — (1) Do not allow the bull to mix with the herd; take the cows to the bull for service when considered clean. (2) Wash out the sheath of the bull after service of a suspected unclean cow.

(3) Isolate a cow immediately abortion has taken place, or preferably before the act has taken place, if possible. (4) Destroy the foetus and all discharges afterwards by burning or with lime. (5) Keep the cow in isolation until all dischargo has ceased, and do not allow service until at least six weeks after all discharge haß ceased. (6) Frequent and regular douching and washing of tho womb and external genitals immediately after abortion and while the discharge is coming away. (7) Tho solutions for douching recommended are weak solutions of Gondy’s crystals in water, or normal saline solution (one ounce salt to a gallon of water). (8) By rearing his own heifer calves the farmer is independent of outside buying, hence loss risk of introducing the disease into a clean herd. (9) When disposing of aborting animals send them to the works. Tho risk of contaminating saleyards and other clean cattle at sales is a serious consideration.

(10) When buying animals to introduce into a clean herd, buy subject to passing the agglutination test. (11) Bulls should not bo allowod to wander at large; the scrub bull is always a inenaco in this respect. To effectively deal with the above recommendations extra labour on many farms would appear to be necessary. At the same time the extra returns from an abortion-free herd, and a reduction of the incidence of tho disease in the Dominion as a whole, with the consequent increased annual output of milk and milk products, would recompense several times the extra labour involved. The question requires the careful consideration of every dairy farmer, a closer watch over tho management and care of the herd being very necessary factors in the control of this disease.