PATHOLOGY 81 



One hundred and four degrees P. is called high, 106 degrees F. 

 very high. Normal temperature of adult cattle varies from 100 

 to 102.5 degrees; of sheep from 100 to 104 degrees. The ner- 

 vous system has control of body temperature through heat pro- 

 duction and heat loss, increasing or decreasing production by 

 tissue oxidation, and increasing or decreasing loss through con- 

 trol of the amount of blood sent to the surface of the body, more 

 or less perspiration, etc. The body temperature, like the tem- 

 perature of a room, is therefore a balance between heat produc- 

 tion and heat loss. 



Heat production. — The source of animal heat is the oxidation 

 of body tissue and fuel materials in the blood and the conse- 

 quent breaking up of complex chemical compounds into simpler 

 ones. The principal heat-furnishing organs are the most active 

 organs, e.g., the muscles and secreting glands. 



Heat expenditure. — Body heat is normally expended about as 

 follows: warming food and drink, 2 per cent; warming air in 

 lungs, 5 per cent; evaporation from lungs, 8 per cent; evapora- 

 tion of moisture from the skin surface and radiation from skin, 

 85 per cent. The expenditure of heat in evaporation of moisture 

 from the skin surface is very much larger than in either of the 

 others. On an average there is sufficient heat developed daily in 

 the body of a medium-sized horse to raise 4550 gallons of water 

 1.8 degrees F. 



Symptoms of fever.— Chill and elevation of temperature ; dry, 

 hot skin; quickened pulse and respiration (normal pulse of 

 horse, 36 to 45; normal respiration 8 to 14 per minute) ; scanty 

 urine, and checked secretions in general, milk, perspiration, etc. ; 

 loss of flesh and constipation, are symptoms of fever. 



Kinds of fever. — Classified according to course, the kinds of 

 fever are: (a) continuous, with but slight variation in tempera- 

 ture, (&) remittent, the temperature varies greatly during the 

 day, but does not descend to normal; (c) intermittent, the tem- 

 perature varies at different portions of the day and reaches nor- 

 mal each day; and (d) relapsing, the fever recurs at intervals, 

 with periods of one or more days of normal temperature be- 

 tween. 



Results.— (a.) Emaciation, or general atrophy, which is more 

 or less severe, according to the duration and height of the fever, 

 and is caused by continued unusual oxidation of body tissues 

 during the fever; (Z>) death may occur; or (c) recovery may be 



