THE VETERINARIAN.

New Zealand Mail, Issue 914, 6 September 1889, Page 19

THE VETERINARIAN.

BLACK LEG IN YOUNG STOCKAmong the blood diseases from which animals suffer, the affection known as blackleg, whi :h is common to calves in certain districts, and is occasionally observed to attack sheep. i 3 one of the most fatal. Recovery is a rare occurrence, and there is always a doubt as to the truth of a reported cure, because of the well-known deadly character of the affection, and the fact that no form of treatment has been found to influence the result. Now and then someone tries some mixture of drugs which would have killed a healthy calf at once, and reports that, after lying between life and death for some hours, the animal got up and began to feed. Such cases are of no practical valne, as they are never reported by experts, who would be capable of appreciating all the conditions ; and in no instance which we have heard of has the evidence of the nature of the disease been sufficient to justify any definite conclusions. ( Black-leg has been carefully investigated by scientists in various parts of Europe, but it cannot be said that our knowledge of its pathology, causes, and curative treatment has been much advanced. Something has been done in the direction of prevention ; but even on that point the experiments, in this country at least, have not been carried far enough to enable us to say that a certain mode of inoculation will secure the animals from an attack of the disease. The great difficulty which meets eyery attempt to determine the value of protective measures is the uncertainty as to the course of the disease under ordinary circumstances. It is known that particular pastures are dangerous, and that, of a number of calves fed on them, a proportion will be attacked and will die. Sometimes the percentage is very low, and at others very high ; but while all the calves are exposed to the same conditions, the majority of them remain unaffected. Consequently, the actual results of inoculation or other preventive means can only be determined by a series of experiments carefully arranged and extended over a considerable time, and including a large area of ground which is known to be dangerous. ‘ Symptomaticanthrax ’ is the technical name by which black-leg is distinguished in Prance ; and the title suggests a relationship to anthrax or splenic fever, from which, however, blackleg differs in important £>oirits ; indeed, the twp, diseases are only associated in the comparatively unimportant particulars of the suddenness and fatal character of the attack, and the dark, sometimes bl-iok, colour of the. parts in which the effects of the disorder are mast ngafked. Anthrax \s reoogr.feedby its special organism, vffiich has very distinct characters, and a lifehistory which has been completely illustrated. The localisation of the disease to a portion of one limb, aud the different positions of the microbe, are the principal distinctions between anthrax and symptomatic anthrax or black-, leg. In the general circumstances under which they occur the two affections are closely associated. Anthrax and black-leg occur in certain localities from time to time. Of the two diseases, black-leg is the most persistent. Some meadows have the peculiar property of causing the disease in a varying proportion of the animaJs fed on them every year, and the same is true in respect of anthrax. In other cases outbreaks occur at intervals, and often when the disease is looked for it does not appear. Exactly the same may be said of anthrax. Respecting the contagious nature of anthrax and black-leg, it may be' stated as » fact, which lias been demonstrated over and over again by experiment, that both diseases are inoeulable with perfect • certainty, but neither spreads from a centre, like others of the true contagious maladies—i.e., it does not follow that, because your neighbour has on his farm an outbreak of anthrax or black-leg, your stock runs any appreciable risk, as they certainly would it the disease were foot-and-mouth disease or swine fever. SYMPTOMS OF BLACK-LEG. Farmers who live in districts where blackleg is common have no difficulty in distinguishing the disease. The first signs of illness —a dull.aspect, desire to.escape from thejherd and seek a secluded place under a hedge or in a ditch r-are accepted as warnings of the impending attagk, and so.on. after wards the appearance of swelling in the hind quarter, or the fore lingb in rarer with the peculiar sensatiqn, rather than sound, which is caused by pressure on the swollen part, leaves no room for doubt as to the nature of the disease. A fatal termination is expected to follow closely on the development of the symptoms above described; but in many cases no sign of disturbance is detected. A calf is left in apparent health, and in an hour or two afterwards is found dead in a corner of the field. ' Treatment of black-leg is seldom attempted, and the important point is to select from among the several preventive measures which are recommended. Setons in the dewlap have long been a favourite means of prevention. Their action as counter-irritants is quick and continuous, but no explanation of their influence in preventing black-leg has been offered. As substitutes for setons, counter-irritants to the tip of the tail have been reoommended. A mixture of turpentine and cayenne pepper is sometimes used. The tail is slit at the end and immersed in the mixture ; and it is claimed for this system that calves which have keen treated in the manner from black-leg. Food mixed With'about 5 per cent of nitrate of potash"appears to be to some extent preventive/'' Inoculation with the virus of the. disease, 'modified by cultivation, has been tried oh the Continent with considerable, success. In this cduntry it has not been found sq effective. The* material employed is generally the muscle juice of the diseased part, dried at a certain temperature, powdered, and then further cultivated at fixed temperatures. Or the muscle juice is mixed with tea times the quantity of water, and a few drops are

injected into the blood. Both plans of inoculation must be done by an. expert, and the latter mode of operation is. not free from risk, even when a skilled veterinarian performs it. 1 >' . . The ordinary remedies of the sefcon in the dewlap and the use of medicated. food as 2oz. of meal or oilcake per day, containing XOgrs. of nitre —are certainly worth a trial, and are not in any way likely to do harm.