CONTAGIOUS ABORTION.

Taranaki Daily News, 12 June 1926, Page 16

CONTAGIOUS ABORTION.

SOME THEORIES EXPLODED. Some widely accepted theories concerning the cause of contagious abortion were exploded by Dr. A. L. Sheather, of the Research Institute of Animal Pathology, Royal Veterinary College, Camden Town, London, in an address to Lancashire farmers. Dr. Sheather said that in the days before the test was discovered it was generally believed that the bull played a great part in disseminating the disease, but it had been proved conclusively that the bull had little to do with its transmission. He would not deny that on occasion the bull might act as a sort of mechanical carrier of the infection from cow to cow, but the risk was so small he thought it might be neglected altogether. Shortly before he left London, Sir John McFadyen instanced the case of a very large heard in which it was known that contagious abortion existed. It was found that one of the bulls was a reactor, and Sir John decided to carry’ out a field experiment and divide the herd into two lots. One lot of cows was mated with a clean bull, and another lot with that which had reacted; but there proved to be fewer cases of abortion in the latter than in the former group. At the time of abortion and for a short period afterwards, there was a certain amount of discharge from the cow, and this contained the microbes in enormous numbers. That discharge was liable to contaminate hands, clothing, and boots of the attendants, or the utensils used, and it was from tainted food or water the immense majority of animals was infected. THE GENERAL PERIOD. Statistics relating to very large numbers of cattle showed that the calf was sliped, as a rule, about the seventh month, and that there were comparatively few cows that aborted a second time. The explanation was that they had been immunised, and, like the great majority of human beings who had had smallpox, whooping cough, or measles, they did not experience a second attack. Therefore, a man who had contagious abortion on. his premises, provided he did not keep buying in animals, but relied upon stock of his own breeding, would find the disease tend to die down and a condition of immunity become established. If they were situated so that they could isolate in every sense of the term —separate buildings, separate grounds, and separate attendants —they could do a great deal towards getting rid of the disease. Most farmers, however, were not in a .position to enforce strict isolation, and they must resort to other means. If thej’ were constantly buying in cattle, they were running a risk, unless they bought subject to the abortive test, and if that plan was not adopted the best method was to use thevaccine supplied by the Ministry of Agriculture.