Insolation. Sun- stroke. Thermic Fever. 43 



and other emanations from the lungs, the exhalations from the 

 skin, dung and urine, accumulate in the air immediately sur- 

 rounding the animal and respiration becomes increasingly imper- 

 fect and difl&cult. This condition is further aggravated by the 

 accumulation of the animal heat in the body. The blood circu- 

 lating in the skin can no longer be cooled, to return with refrig- 

 erating effect on the interior of the body, the cooling that would 

 come from the evaporation of sweat is obviated by the suppres- 

 sion of that secretion, as well as by the saturation of the zone of 

 air immediately surrounding the body, and thus the tendency is 

 to a steady increase of the body temperature until the limit of 

 viability has been passed. 



The mechanical restriction of respiration should not be over- 

 looked. In European soldiers landed in India and marched in 

 the tight woolen clothing and close stocks a high mortality has 

 been induced and in horses with tight girths or collars and short • 

 bearing reins, and oxen working in collars a similar result is ob- 

 served. Any condition of fever is a potent predisposing factor. 



Horses or cattle that are put to violent or continued exertion 

 when too fat or out of condition are especially subject to sun- 

 stroke. Fat cattle driven to market under a hot sun, or shipped 

 by rail, crowded in a car and delayed on a siding under a hot sun, 

 with no circulation of air, often have insolation in its most violent 

 form. The same may be seen in the hot stockyard, with a still 

 atmosphere and the fat animals subjected to the full blaze of a 

 July sun. The chafed feet caused by travel, and the muscular 

 weariness caused by standing in the moving car are material ad- 

 ditions to the danger. 



Similarly horses suffer on the race track when subjected to 

 protracted and severe work in hot weather, or again dragging 

 loads in a heated street under a vertical sun, or on a side hill, 

 with the sun's rays striking perpendicularly to its surface. 



A change in latitude has a decided effect, the Northern horse 

 suffering much more frequently than the one which is native to 

 the Southern States and which has inherited the habit of heat 

 endurance. 



Finally faults in feeding and above all watering are appreciable 

 factors. The privation of water in particular is to be dreaded. 

 Tracy in his experience with American soldiers in Arizona found 



