CHAPTEE XVII 

 DIAPHORETICS AND ANTIHYDROTICS 



DIAPHORETICS. SUDORIFICS 



DiAPHOEETics are agents which increase the secretion of sweat, 

 while diaphoresis is profuse sweating. As a class of drugs they 

 are of minor importance in veterinary practice, since the horse is 

 the only animal with well developed sweat glands in a large area of 

 the skin. Cattle do not possess them to any extent and dogs and cats 

 only in the pads of the feet. Diaphoresis may be produced in the 

 following ways : 



1. Directly increasing the secretory activity of the sweat glands. 



a. Stimulation of the sweat glands either directly or re- 

 flexly. 



b. By stimulation of the peripheral nerve endings or glan- 

 dular cells. 



II. By action on the circulation in the shin. 



a. Locally. Irritation of the sensory nerves of the skin. 

 Counterirritation. 



b. Systemically. 



1. Indirectly. Else of blood pressure if the cutaneous 

 vessels are not simultaneously constricted. 



2. Directly. Dilatation of the cutaneous vessels either 

 directly or reflexly or paralysis of the constrictor 

 mechanism. 



The character of the sweat differs also as to whether it is produced 

 by I or II above. In I, produced by action on the glands, the sweat 

 is more concentrated and less alkaline, the skin being cold and blood- 

 less. This is the so-called " cold sweat " seen in collapse and is 

 usually and rightly considered a serious symptom, as it is an indica- 

 tion of asphyxia. It is caused by stimulation of the sweat center by 

 the CO2 in the venous blood. 



In II, sweat produced by increased circulation, the skin is warm 

 and red (in unpigmeiited spots). This sweat is low in solids and 

 resembles a serous exudate. Dilatation of the cutaneous vessels pro- 

 duces an increase in sweat when other conditions are favorable yet the 

 sweating mechanism may be entirely independent of this dilatation. 



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