MEDICINES ACTING ON THE SKIN 121 



enteritis in many horses, becomes encysted in the mucous 

 coat of the caecum, colon and rectum, and is thus protected 

 from the action of medicinal agents. Several species of 

 Uncinaria burrowing in the mucous coat of the bowels of 

 dogs and cats produce a pernicious anaemia (Friedberger) . 

 The treatment of such cases is limited to a dose of aloes, 

 with antiseptics, nutritive food, and tonics, to sustain failing 

 strength. 



MEDICINES ACTING ON THE SKIN 

 DIAPHORETICS SUDORIFICS ANHYDROTICS 



The skin, in the domesticated animals, besides being pro- 

 tective and tactile, secretes sweat and sebaceous matter, 

 exerts to a very slight extent a modified respiratory function, 

 and, on account of its constant and large secretion of fluid, 

 is an important factor in regulating animal temperature. 

 The sweat is a clear colourless fluid containing only about 

 two per cent, of solids, of which sodium chloride is the chief. 

 There are also traces of fatty acids, but there is little or 

 no excretion of nitrogenous waste products except under 

 pathological conditions. In cases of kidney disease, urea 

 is excreted to some extent by the skin. In the dog and 

 rabbit it has been found that removal of the hair and var- 

 nishing of the skin causes rapid lowering of temperature 

 and death, due to the great loss of heat from the skin, the 

 vessels of which are dilated. This result can, however, be 

 prevented by wrapping the animals in cotton wool, and 

 since neither of these animals sweat naturally, death cannot 

 in any case be due to non-excretion of poisonous waste 

 products through the skin. Thus the only important effect 

 of the secretion of sweat is to cause a loss of heat from the 

 skin by evaporation of the fluid. 



The sweat glands, placed in the subcutaneous adipose 

 tissue, number 2000 to 3000 on every square inch of the 

 surface of men and horses. Their activity is regulated by 

 the special centres which are situated in the spinal cord. 

 The amount of natural perspiration depends mainly upon 

 the dryness and temperature of the air. Sweating in men 



