6 INTRODUCTORY 



faulty methods of feeding. The following predisposing causes 

 of disease may be mentioned: 



Age is an important factor in the production of disease. 

 Young and immature animals are more prone to attacks of infec- 

 tious diseases than are old and mature animals. Ilog-cholera 

 usually affects the young hogs in the herd first, while scours, 

 suppurative joint disease and infectious sore mouth are dis- 

 eases that occur durincr the first few days or few weeks of the 



' — ' ' jri. 



Fig. 2. — Insanitary yards. 



animal's life. Lung and intestinal parasites are more commonly 

 found in the young, growing animals. Old animals are prone to 

 fractures of bones and degenerative changes of the body tissues. 

 As a general rule, the young are more subject to acute diseases 

 and the old to chronic diseases. 



The surroundings or environments are important predis- 

 posing factors. A dark, crow^dcd, poorly ventilated stable lowers 

 the animal's vitality, and renders it more susceptible to the 

 disease. A few rods difference in the location of stables and 



