UNIVERSITY OF CALIFORNIA Agricultural Experiment Station 
 
 College of Agriculture e. w. hilgard, director 
 
 BERKELEY, CALIFORNIA 
 
 CIRCULAR No. 2. 
 
 (May, 1903.) 
 
 BLACKLEG 
 
 By ARCHIBALD R. WARD, 
 Veterinarian and Bacteriologist. 
 
 Synonyms. — Blackleg is also known as Symptomatic Anthrax, Em- 
 physematous Anthrax, Quarter 111, Black Quarter, and Rauschbrand. 
 
 Animals Affected. — For all practical purposes the disease may be con- 
 sidered as merely one of cattle, occurring chiefly among young stock 
 between the ages of three months and four years. Cattle under three 
 months are naturally immune, and for the same reason animals over 
 four years but rarely are attacked. It is a matter of common observa- 
 tion that calves in good condition are more liable to attack than poorer 
 ones. Nevertheless, it is not safe to consider that poor condition will 
 confer immunity against blackleg. The disease is not communicable 
 to man. 
 
 Symptoms. — The most important symptom is the occurrence of swell- 
 ings under the skin on any part of the body except on the legs below 
 the knees or hocks. The swellings when first appearing are painful, but 
 as they become larger the skin in the center of the swelling becomes 
 insensible. The enlargements are, to a large extent, composed of gas 
 bubbles imprisoned in the loose tissues beneath the skin, and the large 
 ones, when pressed, give forth a very characteristic crackling sound. 
 When a swelling is tapped with the finger, it emits a drum-like resonance. 
 When occurring upon the legs, the tumors may cause lameness and 
 even prevent the victim from walking at all. If the tumor is cut open, 
 black or frothy blood runs out. Fever is present and is manifested by 
 the usual indications, such as quickened breathing, dullness, and loss 
 of appetite. Death occurs within a period varying from eight hours to 
 two days after the beginning of the attack. 
 
 Changes Observed After Death. — The carcass bloats rapidly and like 
 wise decomposes quickly after death. When swellings are cut open they 
 are found to contain more or less clotted black blood and gas. The 
 
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 excessive blackening by blood gives rise to the various names, such as 
 black quarter and blackleg. Some internal organs are more or less 
 affected, but the changes in the internal organs need not be considered 
 in recognizing the disease. 
 
 Cause. — The disease is brought about by bacteria which live naturally 
 in the soil and which gain access to the body through wounds, and more 
 rarely with food eaten. The germs of blackleg are quite generally dis- 
 tributed, but certain soils have been observed to offer particularly 
 favorable conditions for their existence, and in consequence are especially 
 dangerous for stock pastured thereon. Among these are damp or water- 
 logged soils, or heavy clay soils. Punctured wounds, such as those 
 produced by barbed wire, briers, stubble, etc., are regarded as fruitful 
 sources of infection. A diseased animal is not regarded as a direct 
 source of danger to other animals in contact with it. If the swellings 
 have been cut open and blood is discharged, there is more danger. 
 
 Disposal of the Dead. — Burning is preferable to any other method of 
 disposal, as it is the only means that can be relied upon to absolutely 
 destroy all germs of the disease with which the carcass is teeming. 
 When the victim is buried the germs will remain alive in the soil long 
 after the carcass has decomposed, and will constitute a menace to the 
 health of stock pastured upon the land. Earthworms are said to 
 convey infection to the surface. 
 
 Treatment Useless. — No successful treatment is known, and even should 
 a remedy be discovered, its usefulness would be limited, owing to the 
 rapidly fatal nature of the affection. Cutting open the swellings and 
 injecting various medicines has seldom met with success. Excessive 
 exercise and bleeding have also been found next to useless. 
 
 Prevention by Vaccination. — The method is based upon the principle 
 that an attack of the disease may be warded off by purposely causing 
 the animal to have an exceedingly mild attack by artificial means. 
 Vaccine is prepared by obtaining flesh from a diseased animal, finely 
 dividing it and subjecting it to a high temperature for several hours. 
 This treatment of the diseased material reduces the disease-producing 
 power of the blackleg germs that it contains. The vaccine material, 
 when injected under the hide of a healthy calf, produces little or no 
 visible effect upon the health, but experience shows that this vaccina- 
 tion protects the animal from catching the disease naturally for a year 
 or more. The method was originated in Europe in 1883, and has since 
 been improved upon and used in all districts of the civilized world 
 where stock-raising is carried on extensively. Vaccination as a pre- 
 ventive of blackleg has been and is encouraged by the Bureau of 
 Animal Industry of the United States Department of Agriculture and 
 
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 the Agricultural Experiment Stations in the various States. Its use has 
 long since passed the uncertain experimental stage. 
 
 When Not to Vaccinate. — Calves should not be vaccinated unless it is 
 known that the disease has previously occurred among animals pastured 
 on the same land. When vaccination is practiced there is great risk of 
 introducing the germs of the disease and thus infecting the land, which 
 would necessitate vaccinating annually thereafter. A stock owner can 
 much better afford to ascertain that his range is infected by waiting 
 until a death has occurred, than to rush into vaccinating before he is 
 certain that it is necessary. Blackleg does not sweep over a region rapidly 
 like some infectious diseases. Do not castrate or dehorn at the time 
 of vaccination. Do not vaccinate animals already stricken with the 
 disease. ' 
 
 What Animals to Vaccinate. — Animals between the ages of five months 
 and two years should be vaccinated several weeks before the disease 
 usually appears. Animals older or younger occasionally die of the 
 disease, but it is not profitable to vaccinate against these attacks, for they 
 occur rarely. If animals under six months are vaccinated, the process 
 should be repeated the following year. The operation is facilitated by 
 confining the calves in a chute. 
 
 Where Vaccine May Be Obtained. — The Bureau of Animal Industry, 
 United States Department of Agriculture, Washington, D. C, furnishes 
 vaccine free to all applicants. Each stock owner must apply directly 
 to Dr. D. E. Salmon, the Chief of the Bureau of Animal Industry, and 
 an application blank will be mailed to him, upon which the owner shall 
 indicate the amount needed, etc. Under no circumstances will blackleg 
 vaccine be sent to any one person for distribution to others, or for use 
 upon other cattle than his own. For administering the vaccine, a vac- 
 cinating outfit must be obtained, costing from $4 to $6. The outfit can 
 usually be readily obtained through drug stores. Vaccine prepared by 
 private firms can be purchased from the druggist or directly from the 
 addresses below. Firms preparing vaccine, known to the writer, are: 
 The H. K. Mulford Co., represented by Thomas G. Finley, 41 Stevenson 
 street, San Francisco; The Cutter Analytic Laboratory, Rialto Build- 
 ing, San Francisco; The Pasteur Vaccine Co., represented by Cadogan 
 & McClure, 110 Jessie street, San Francisco; Parke, Davis Co., Detroit, 
 Michigan. The various manufacturers supply vaccinating outfits and 
 furnish plainly worded directions for use.