Contagious Abortion

Franklin Times, Volume XXIX, Issue 19, 19 February 1940, Page 6

Contagious Abortion

PREVENTION OF DISEASE CHAMBER OB COMMERCE BULL ETLN Tiie Canterbury Chamber oJ' Commerce agricultural bulletin l'or January, prepared by Canterbury Agricultural College, deals with the matter o! contagious abortion in cattle. The bulletin deals with the incidence and importance of the disease, its cause, spread, symptoms, diagnosis and prevention and control. Under the last mentioned section the bulletin states: Contagious abortion of cattle is one of the common diseases of cattle for which there is. as yet, no satisfactory treatment. It becomes the more important to pay particular attention to ils prevention and control, a task which is rendered relatively easy by the high order of accuracy of the diagnostic blood test.

In clean herds the chief object is to prevent entry of infection. In the majority of cases, infection is introduced by the purchase of cattle from infected farms. All cattle therefore should he purchased subject to their passing the agglutination test. If bought from a property not known to he free of the disease they should he isolated on the farm and retested" in one month. This retest is particularly important if Ihe cow is in calf or lias calved but recently, before the first test. Farmers who buy cattle on the open market with no knowledge of the previous history of the purchased stock are almost certain to introduce this serious disease into their herds. Need For Isolation If, in a hitherto uninfected herd, a suspected case of abortion or retention of the afetrbirth occurs it should he treated as a case of contagious abortion until proved to be due to other causes. The animal must be immediately isolated, its stall and surroundings thoroughly disinfected and the dead calf, afterbirth and all discharges destroyed by burning or by burial after treatment with quicklime. The isolation must be maintained until all discharge ceases, and service should not lie allowed until at least two months after this time. In such cases as tin's and where the agglutination test shows only ;i small portion of infected cows, the best procedure is to eliminate infected cows from the herd by sending them to the works for slaughter. Their disposal in any other way is almost certain to spread the disease still further. As a further safeguard the whole herd should be retested at intervals to ensure that no more cases are developing.

Control and eradication are difficult if the disease is well established and a large proportion of the herd is

infected. Under favourable economic conditions, however, it is possible, and in some countries, control and eradication are still widely practised. All mature cattle—cows, heifers and bulls—are tested and then separated into fwo lots, reactors or infected cattle, and non-reactors, and these two groups must be completely separate: actually, two entirely distinct herds being run on the same farm. Newly purchased stock from clean herds, or non-reactors, are added to the clean group. Calves from the infected group may he used to build up the health group. They may be left on their mothers until weaning, after which they are separated until mature and usually tested before being added to the clean herd. Calves under six

months of age are considered insusceptible to the disease. If one bull is kept for the whole herd. infected cows should he brought to him for service and the ground and his coat should be sprayed with a disinfectant after service. The long hair at tiie opening of the sheath should he cut short, and it is a good practice to syringe out the sheath with a nonirritant. antiseptic solution after each service. In no case should the bull be allowed to run with the infected portion of the herd.

Eradication Not Easy This method oi‘ eradication is no'; easy, success depending chiefly on the complete isolation of the healthy and diseased stock. On farms where a high proportion of the herd is infected, and where the maintenance of two completely distinct groups is found to lie impracticable—and, no doubt, there are many such farms—a three year plan of eradication, such as the following, may he put inlo opera I ion. Test all adult cattle on the farm in order to determine the number of reactors. Oslimale from this the total number of replacements that will be necessary in three years’ time. Relain all heifer calves in the next iwo seasons. and after weaning send them In graze by themselves on a sheep farm: it may be necessary io purchase a few well bred extra calves. -Male I hem so that they will all calve

in one season, i.e., approximately half at two years old and half at three years old. Retest all stock in the herd and dispose of the reactors; then replace the reactors with the first calf being tested. Keep the heifers in isolation unlit all the cows in the main herd have passed three consecutive tests at intervals of four to six weeks. Bring the heifers on to the farm in late autumn'and graze them on the previously hayed ureas, the aftermath of which has been top dressed and kept specially for this purpose. The paddocks lasi grazed by the infected slock should then be closed and cut for hay in the following season.

Such a policy is usually more practicable than the method of separation into two groups and should prove economically beneficial to all parties concerned.