GICNICRAL lONSlDI-IKAIlON OF ]JI SMASIC. 43 



Animals are naturally protected from the effects of low teni- 

 oeratures, m dry weather, by their coat of hair, fur, wool or 

 weathers. When their protective coat becomes wet it no lonoer 

 prevents heat dissipation consequently animals havinrr no shl-l- 

 ter, as ranch horses, cattle, and sheep, frequently die in t,'reat 

 numbers during- the early cold sprino- rains. 



The local lesions caused by low temperature are practically 

 the same as those resulting from exposure to high temperature. 

 Tlius exposure to a mild, low temperature produces hyper- 

 enna; exposure to freezing temperature produces inflammation 

 accompanied by a serous exudation but the exudate rarely 

 accummulates and forms a vesicle as in burning. Exposure to 

 extreme low temperature produces necrosis, the frozen tissue 

 becoming- dry and hard. 



Animals are most frequently exposed to temperatures suffi- 

 ciently high to produce insolation in the daytime, in the tropi- 

 cal or temperate zones, although overheat is sometimes oliserved 

 during the night. Exposure to temperatures that produce local 

 burning usually occurs in conflagrations of buildings. Scores 

 of animals die, in tlie spring, on ranges or large pastures, in the 

 temperate zone, as a result of diminished body temperature ii-i- 

 duced by exposure to cold rains. These animals are usually 

 depicted because of insufficient or non-nutritious food. Their 

 coat of hair or wool becomes saturated with water and thus the 

 body temperature regulation is disturbed. Lesions produced by 

 lo\y temperatures are evident only in regions and seasons, where 

 there is a low atmospheric temperature. Local freezing usually 

 occurs in extremities as the ears, tail and feet. 



2. Photic. — Exjiosure to sunlight frequently produces derma- 

 titis, especialh' in those animals having a thin, light colored skin. 

 \A'hite hogs are quite serioush^ affected by sunburning, in some 

 localities. This pecidiarity prohibits the raising- of white hogs, 

 in certain districts in Africa and Central America. R. Paine, F. 

 R. C. V. S., of the Department of Agriculture of Cape Colony, 

 in the Journal of Comparative Pathology and Therapeutics, 

 Part 1, \''ol. XXL reported some cases of dermatitis ii-i cattle, 

 that were undoubtedly the result of exposure to sunlight. D. j\l. 

 Campbell observed about 40 Duroc Jersey pigs affected with derma- 

 titis induced by sunlight. 



Direct or reflected sunlight is also injurious to the eves of 

 domestic animals. The injurious effects are noticed more es]-)eci- 

 allv in animals driven upon macadam thoroughfares or over 

 light colored soil. Electric and gas lights have also been 

 found to be injurious to the eyes of various animals especially 



