838 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



by infected milk. Hogs receive their infection from the milk of 

 tubercular cattle or from the manure or carcasses of such cattle in 

 feeding yards. Unventilated stables are favorable for the spread of 

 this disease because with insufficient ventilation the bacteria are not 

 carried out, but become constantly more numerous. The tubercle 

 bacterium is quite resistant to drying, but is rather sensitive to sun- 

 light. It is usually destroyed by moist heat in six hours at 55; in 

 twenty minutes at 60; and generally in five to twenty minutes at 

 95, depending upon the protection it may have. 



Conditions of sensible sanitation are of the utmost importance. 

 These include exercise, sunlight, and ventilation, particularly sunlight. 

 In order that effective control work may be done among animals, 

 tuberculin must be used freely and conscientiously. 



The method of dealing with diseased herds depends upon breeding 

 and value. Common cattle are usually dealt with most economically 

 and efficiently by slaughter with a view to using such carcasses as may 

 pass inspection. Valuable cattle, especially pure bred animals, may be 

 used for breeding purposes, gradually building up a sound herd and 

 gradually displacing the diseased animals. This latter plan is usually 

 unprofitable and unwise except for very valuable cattle. 



FOOT ROT OF SHEEP* 

 Bacillus necrophorus 



This is an infectious disease of sheep characterized by an ulcerative 

 inflammation of the tissues just above the horny part of the cleft of the 

 hoof. It is seen in Europe, England, Australia, and the United States. 

 Sheep are made lame and if the disease is not checked by appropriate 

 treatment, the hoof becomes greatly distorted, the sheep being finally 

 unable to walk. Mohler and Washburnf state that foot rot is caused 

 by B. necrophorus, this organism being associated with pus-producing 

 micrococci. B. necrophorus, which is a strict anaerobe, tends to grow 

 out into long filaments; it is stained by the ordinary aniline dyes, but not 

 by Gram's method. Rabbits and white mice are susceptible to inocu- 

 lations of this bacillus, but guinea-pigs appear to be immune. The 

 disease is treated by causing infected sheep to walk through a 

 disinfecting solution, such as a 3 per cent solution of carbolic acid. 



* Prepared by M. Dorset. 



t Bull. 63. Bur. An. Industry, U. S. Dept. Agr., 1904. 



