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Show 'Blackleg' Outbreak Threatens Cattlemen TROPIC A new outbreak of what appears to be Blackleg has claimed additional cattle in the Bryce Valley area and is causing fears of a large outbreak. Local cattlemen however, feel that because of the careful and methodical vaccinating measures being taken, the outlook is guardedly optimistic. To date the fast-moving and nearly always fatal disease has claimed at least 30 animals in the area. It was feared for awhile that the Blackleg problem might decimate some herds. Cattle ranchers are assuming the disease is Blackleg but experts say it could be Malignant Edema because the two diseases resemble each other so closely. Even a differentiation between the two by scientific examination of the body of a dead animal is unreliable and, unless examination is made of a live sick animal or immediately upon death, results can be indeterminate. Malignant Edema, like Blackleg, is found world wide, The look-alike, act-a-like similarity between the two includes infection coming from an injury being contaminated by bacteria-laden water. (Continued on Page 6) Blackleg . . . (Continued from Page 1) The bacteria can lie dormant for as long as 50 years in the soil, only to spread as water becomes available to activate them, frequently causing widespread contamination. The two diseases are also spread when birds eat the carcasses of animals which have died from the disease, drinking in irrigation ditches and also when the droppings from the birds infect the water and soil. The Merck Veterinary Manual (1973) currently in use by the Utah State University Extension Service states that "animals under six months of age are seldom affected, probably being protected by maternal immunity," as many local ranchers have believed. The statement should be considered cautiously states Extension Agent Verl Matthews who says, "The only time a calf has an immunity is when the mother has been challenged by (exposed to) the disease and has lived through it." Cattle ranchers in the area have long believed that young calves up to three months are immune and mat Blackleg cannot be contracted in areas as low in elevation as sheep creek where the first local outbreak occurred. New studies and information are now available which appear to contradict both the manual and long held local beliefs. Mathews said that studies show that for the low cost of vaccines and the small amount of labor expended, vaccination of all cattle and boosters should be the normal and expected procedures in all cattle operations. In sheep neither disease is restricted to the young and is usually caused by injuries such as sheering cuts, docking, crutching or castration. Blackleg in sheep is uncommon in the U.S. It is more common in New Zealand where it is seen more often In sheep than in cattle. Matthews stated that the University Extension Service recommends vaccinating cattle for Maligant Edema and for Blackleg. The extension service also recommends vaccination for Bacillary Hemoglobinuria commonly known as Redwater disease if animals spend any portion of a 12-month period in wet pastures or meadows. |