138 THE HORSE IN HEALTH AND DISEASE 



under Determining Causes on a later page will show. Chief among 

 the predisposing causes of disease are climate, heat, cold, food,, 

 water, air, exercise, work, and auto-intoxication. 



Climate plays an important part in causing disease. A warm, 

 moist climate is most favorable for the development of infectious 

 diseases and those caused by animal parasites. A cold, dry climate 

 gives conditions most conducive to the preservation of health, as it 

 is antagonistic to the growth of germ life. 



Heat is not dangerous unless the temperature of the atmosphere 

 rises above 101° F., the normal for the body of the horse. Higher 

 temperatures predispose to heat- and sun-stroke. If the animal 

 sweats freely, and the excretion is readily evaporated, much higher 

 degrees of temperature can be borne without harm. 



Cold acts either locally or generally. When excessive it leads 

 to frost-bite, which may be followed by death of the affected part. 

 Protracted exposure to cold reduces the resistance and predisposes 

 to catarrhal affections of the respiratory organs. 



Food may be either a predisposing or direct cause of disease. 

 When fed to excess it causes distention of the stomach and may 

 even lead to rupture of that viscus. Gases are formed in the 

 stomach and intestines from decomposing and fermenting foods. 

 When the natural channels of escape are unable to take care of 

 these gases, bloating results. Insufficient food causes lack of nour- 

 ishment, with loss of strength, weight, and resistive power to dis- 

 ease. When the diet is too dry and highly nutritious it may cause 

 constipation and torpidity of the liver and other organs. If too 

 laxative, it will produce a flaccidity of the whole system and a 

 general lack of vigor. 



Water at the wrong time or at too long intervals may be harm- 

 ful and cause digestive disturbances. Too little water gives in- 

 sufficient fluidity to the food mass and leads to constipation. 

 Animals deprived of water for a long time lose their appetite for 

 solid food, and often develop a persistent diarrhea when water is 

 again provided. Water is a frequent source and conveyor of 

 disease, particularly of those forms that are due to internal animal 

 parasites. 



Air may carry infection from place to place. Epizootics may 

 be spread by high winds or infection carriers, like winged insects, 

 carried by winds over large areas. Contaminated air, particularly 

 when combined with poor ventilation, is responsible for the rapid 



