304 INFECTIOUS DISEASES 



as two or three per cent. Because of the erosions and sloughing 

 of the tissues of the mouth, feet and udder it becomes necessary 

 to kill manj of the animals. Young animals frequently die of 

 inflammation of the digestive tract. The immunity conferred 

 by an attack of the disease is not permanent. 



The most economical measures of prevention and control 

 are to buy and slaughter all diseased and exposed animals, bury 

 the carcasses in quicklime, disinfect the premises '(Figs. 107, 108 



Fig. 107. — Federal inspector exaniining the mouth of a suspected case of foot-and-mouth 



disease. 



and 109) and enforce a district, county and State quarantine 

 (Figs. 107, 108 and 109), until after the infection has died out. 

 This statement may not In^ld true of methods of control in 

 countries where foot-and-mouth disease is widely distributed. 

 Tetanus. Lockjaw. — This is an acute infectious disease 

 that is cliaracterized by spasmodic contractions of volantary 

 muscles. The specific germ remains at the point of infection, and 

 produces toxins that cause tetanic contractions of the muscles. It 

 commonly affects horses, mules, cattle, sheep and swine. The 

 disease is most common in warm, temperate climates. 



