ACTION OF HEAT 505 



hot salt or sand in cloth bags, a flatiron or hot, wet cloths between 

 waterproof coverings. Dry heat is often preferable to moist heat for 

 simply relieving pain and congestion, as animals are less apt to become 

 chilled by drafts and evaporation from the surface afterwards. It is 

 generally more difficult to obtain, however. 



Inhalations of plain or medicated steam are given for their local , 

 effect on the mucous membranes of the upper air passages. The moist 

 heat has a soothing action on the nerves, and tends to loosen dry exuda- 

 tions. Agents may be incorporated in the inhalation having a sedative, 

 stimulating or antiseptic action. (Vid. "Agents Acting on the Respiratory 

 Organs," p. 39.) 



The technic consists in placing a bucket containing a boiling 

 mash under the horse's nose, or in pouring cool water over a heated brick 

 or iron in the bottom of a pail. The practice of tying a bag over a 

 horse's head, and steaming him therein, is bad, if the animal is suffering 

 from respiratory troubles, as insufficient pure air is obtainable. A dog 

 may be placed on the seat of a cane bottomed chair, and covered loosely 

 with a sheet over the whole, the steam being generated in a vessel beneath. 



Hot Baths at a temperature of 98° to 110° F. are impracticable for 

 larger animals. They can be given to the smaller animals in collapse, 

 shock, rheumatism, and to abort cold after exposure. Glowing heat is 

 applied by means of heated metal, and is treated under the section on 

 counter-irritation. , 



ACTION OF HEAT CONTRASTED WITH THAT OF COLD. 



The action of intense heat or cold on animal tissue is very similar 

 in effect, producing vasomotor paralysis, congestion, inflammation, de- 

 struction of tissue and death. Even the sensations to which they give 

 rise resemble each other so closely, that coolies on first handling ice said 

 they could not hold it because it burned their fingers. Strong heat (115° 

 to 120° F.) contracts blood vessels in underlying parts and overcomes 

 pain and congestion. Heat of this degree approaches cold in similarity 

 of action. A moderate degree of heat dilates vessels, while cold of like 

 intensity contracts them. Moderate heat relieves pain by relaxing tissue, 

 diminishes vascular tension by dilating efferent vessels of the collateral 

 circulation, and draining off blood from the congested areas. Moderate 

 cold, on the other hand, accomplishes a similar result in benumbing 

 nervous sensation and lessening the impact of blood in the painful region 

 by constringing the afferent vessels. Tissue change is increased by 

 moderate heat, but decreased by cold applied locally, or generally in 

 fever. Swelling of tissue is reduced by cold directly; only indirectly by 

 heat, which may, indeed, increase it. Softening and sloughing of parts, 

 suppuration and "ripening" of abscesses and "cleaning off" of wounds, 

 are facilitated by moderate heat, but hindered by cold. 



Disinfectants, Antiseptics and Deodorants. 



Disinfectants, or germicides, are agents which destroy the micro- 

 organisms, causing infectious and contagious diseases, fermentation and 

 putrefaction. Antiseptics are agents which prevent or retard the growth 



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