PREVENTION OF BLACK-LEG IN CALVES

New Zealand Journal of Agriculture, Volume 63, Issue 3, 15 September 1941, Page 225

PREVENTION OF BLACK-LEG IN CALVES

Although black-leg has caused many deaths of calves, the disease can be prevented by vaccina- “ l " llhllll "| tion. As the disease is an acute infectious one, §

g each case must be reported so that control meas11..,.. ures may be taken, and it is essential that each rJIIIIIIIIIIIIIIIIIIIIIIII ■ t u Mf t t. a J L • J carcass should either be burned or deeply buried.

By the

LIVESTOCK DIVISION

BLACK-LEG, a microbic disease of calves, is known under several names, such as quarter-evil, quarter-ill, black-leg, black-quarter, etc. Black-leg is caused by the entrance of a special microbe or germ into the system through scratches or abrasions of the skin or through the food. The germ forms spores, which are very resistant, and may live in the soil for several years, which accounts for the disease appearing again after a lapse of years on some farms. In New Zealand the disease is scheduled under the Stock Act, and each case must be reported to the local Stock Inspector of the Department of Agriculture so that adequate steps may be taken to

11■1111111111111111111111111111111B1111111111111111111B11■11111BI Illll■lll■l carry out the necessary control measures. The disease mainly attacks young cattle up to two years of age, but occasionally ’ sheep or older cattle may be affected. Young calves in good condition are the most common . victims, and where dairy farmers raise a number of calves annually it is important that any sudden deaths should be re-

ported, so that the exact cause of death may be ascertained.

Symptoms

The most notable symptom is . the development' of a characteristic swelling underneath the skin of one or more quarters, in which case the affected calf will be very lame. The swelling may appear on the neck, shoulder, breast, loin, or rump. The animal is dull, loses appetite, and becomes very feverish. The swelling becomes tense, and when the hand is passed over it a peculiar crackling noise is heard, due to the presence of gas. When cut into, the affected area exudes bad-smelling fluid of a frothy

nature. The flesh is blackish in colour at the affected area. ' " , Quite frequently, no symptoms are seen by the owner, the calf being found dead. Occasionally, however, the affected calf may linger for a period of from 24 to 48 hours. Death is due to the absorption of poisons produced by the germ.

T reatment

There is no curative treatment for the disease; hence the importance of protecting susceptible stock by vaccination. < In order to prevent the perpetuation of the causal germ or its spores in the soil or the contamination of pastures, it is essential to burn the carcass of an animal which died from the disease. If burning is impossible, the carcass should be buried deeply. If carcasses are not properly disposed of there is every possibility that the germs and spores of the disease will be broadcast by dogs or hawks, thus making the property a permanent

source of danger to unvaccinated calves.

Prevention

The disease is preventable. This means that a potent vaccine is available for use in protecting calves against the disease. When the calves are vaccinated an immunity is set up which enables the animal to withstand any germs that may be picked up. The vaccine is prepared at the Animal Research Laboratory, Wallace ville, and is sent on request to the Inspector of Stock in any district where the disease is known to occur. . Calves will be vaccinated against the disease free of charge at the request of the owner. In order to control the disease effectively’ in a district it is important that all owners should report any suspicious deaths in calves so that the exact cause of death may be determined. If this cannot be carried out in all cases, the owner should burn or bury the affected carcass.

The next step is to arrange to have' all the calves on the farm vaccinated against the disease. It is fatal to try and cover up the disease, as it will recur and become worse from year to year. Neglect in reporting suspicious cases or in burning or burying carcasses is merely aggravating a position which lends itself to reasonable control.