PULPY KIDNEY

Press, Volume LXXIV, Issue 22521, 1 October 1938, Page 13

PULPY KIDNEY

VACCINATION RESULTS CARE IN APPLICATION IMPERATIVE

Discussing the incidence of, pulpy kidney and the effects of vaccination, an Australian veterenarian in the “Australasian,” strikes a warning note about the need for care in the injection of the vaccine. The methods of application have been described in detail on this page, but any further contribution should be useful. Various methods have been adopted to check losses caused by the disease, says the writer, and vaccination has been found to be the most reliable. Upon many properties where losses of 300 or more lambs occurred annually a few years ago, vaccination has been adopted as a regular routine, and no further losses have occurred.

Entero-toxaemia disease is caused by a germ which develops rapidly in the intestine of the lamb when conditions are favourable. The germ produces a toxin which, passing from the intestine into the blood stream, becomes rapidly fatal. The protective vaccine is prepared in the laboratory ■ by growing the infective germ in a suitable culture, and finally killing it by the addition of formalin. The vaccine containing the dead germs is injected with a hypodermic syringe beneath the skin of the lamb. Healthy blood, acting upon the dead germs, produces anti-bodies, which inhibit the development of live germs gaining entrance from the ordinary infective sources. In this way the lamb gains immunity to entero-toxaemia disease. This principle of disease prevention is now widely applied to human beings as well as animals, and many incurable and rapidly fatal diseases have been brought under control by its means. The results obtained by vaccination of lambs have been remarkably good. Flocks vaccinated before the disease has occurred do not develop cases of

entero-toxaemia, but if the disease is already present the progress of the epidemic is arrested within a few days of vaccination. Indeed, so successful has this method of disease prevention become that many hundreds of thousands of lambs are vaccinated each year. Risks of Vaccination During the last 10 years instances have arisen where severe losses have followed vaccination. Naturally the first reaction on the part of the stockowner is to condemn the vaccine used. However, this is not justifiable upon the facts. The vaccines are very carefully prepared. The quantity manufactured in one batch is sufficient to vaccinate many thousands of sheep. Each batch is carefully tested before boing packed in sterile containers by injecting into guinea pigs doses of several times the strength used for a lamb. Vaccine is prepared by the Commonwealth Serum Laboratories and by several private manufacturers, and losses have occurred indiscriminately following the use of vaccine from either source. A few particular instances will help to illustrate what can happen. In one case a farmer vaccinated some 200 odd lambs, using exactly similar methods to those he had used successfully on previous occasions. The following day he noticed an unusual amount of lameness among the treated lambs, and the next day many-deaths had occurred. At the site of the inoculation the skin appeared blackened and bruised, and there was a swelling extending from the forearm, under the chest and along the belly. In all, 80 lambs died, and many recovered only after a long illness. It was found that the cause of this disaster was the germ which produces blackleg. This had gained entrance to the muscles near the site of inoculation, and the lambs had actuallv died from a blackleg infection There are two possible ways in which this might occur. (1) The blackleg germ was present in the muscle either before or just after inoculation had been made; (2) the germ gained entrance through the skin, either being introduced with the needle at the' time of vaccinating, or passing along the needle track afterwards. In either case the damage done to the muscles by the vaccine or the needle, which normally is rapidly repaired, is sufficient to render it suitable for. the blackleg germ to grow and kill the lamb. In supp~ort of the view that the blackleg germ is lying dormant until the muscle is damaged is the wellknown fact that black disease in sheep is produced only when the liver is damaged by the fluke. Moreover,

blackleg of calves is considered to develop when the muscles are bruised, the germ being present or inactive until this occurs. Precautionary Measures The younger the lamb at the time of vaccination the less the risk. Lambs under one week of age are rarely, if ever, infected. This points to the fact that infected skins from infected country are the greatest sources of danger, th s older lambs having a greater degree of skin contamination. In view of the fact that abscesses may be caused and the carcase affected for export purposes, inoculation at an early age is advisable from this aspect. There would then be time for skin lesions to heal completely before the lamb reached marketable age. The most favourable position appears to be under the forearm, and injections should be made under the skin, avoiding puncturing muscle. Finally it has been proved that mortality can occur no matter where the vaccine is manufactured, just as infection can take place after marking, shearing, or any operation where the skin is broken.