414 HORSE, SWINE AND POULTRY DISEASES 



cause was in the animal, in the second, it was in the surroundings. 

 Among the causes of disease we may briefly consider the following: 



Age. Young animals are more subject to attacks of contagious 

 or infectious diseases than old. White scours, suppurative joint 

 disease, and infectious sore mouths are diseases of the first few days 

 or weeks. Thumps occur early. Cholera occurs with much greater 

 virulence in those under six months of age than in the older. Lung 

 worms or whooping cough occurs between two and four months. 

 Swine plague attacks the older hogs. Trichina? likewise more often 

 occurs in mature animals. As a rule, the young are more subject 

 to acute diseases and the old to chronic troubles. The matter of sex 

 has little bearing on the diseases of swine other than those due to 

 farrowing. 



Breed. The matter of breed is of less importance in the dis- 

 eases of swine than in other domestic animals. Some breeds are 

 more active than others and thereby seem to have increased resistive 

 powers to some troubles. For example, pigs from the more active 

 breeds seldom have thumps if allowed to exercise. It is the lazy, fat 

 fellows that are particularly susceptible. 



Care and Feeding. Care and feeding are factors of great im- 

 portance. The feeding of unsuitable foods, as city swill, dirty, sour 

 slop, those containing large quantities of soap, feeding too heavily 

 when too young, feeding full rations of green corn as soon as it is 

 ready, feeding cotton seed, feeding with too limited exercise, pastur- 

 ing upon clover sod where there are many grub worms and upon 

 land known to be infected with parasites, are all factors contributing 

 to some forms of disease. 



Shelter. Sudden changes of temperature, extremes of heat and 

 cold, exposure to storms, etc., all have their effect. Piling under 

 straw stacks and hot sheds predisposes to pneumonia. Lying in 

 damp beds causes skin troubles. The hog does not need a great deal 

 of shelter, but needs that dry and comfortable. 



Location. Sometimes the difference of a few rods makes the 

 difference between having disease in a herd and not having it. A 

 dry, protected site is always preferable to one in the open or low. 



Water Supply. The work of this Station has been such as to 

 prove that only well water, deep well water from a tubular well, 

 can be recommended for all kinds of farm animals. This applies 

 with possibly greater force to the hog than to any other class because 

 cholera, a water borne disease, is the principal scourge. In actual 

 practice, however, the reverse condition prevails. 



Previous Disease. The effect of one attack of an infectious dis- 

 ease as a rule confers immunity against a subsequent attack. This 

 is not true of all, but of many. One attack of cholera will not give 

 complete immunity, but does reduce the chances of a second attack. 

 The effect of one disease may weaken a part and make the animal 

 susceptible to some other trouble, as lung worms make it easy to ac- 

 quire pneumonia. 



Vital Causes. The vital causes are all living organisms, either 

 plant or animal, that act as parasites at any stage of their existence. 



