284 



DISEASES OF THE DOMESTIC ANIMALS 



of blood withdrawn, but the blood-vessels quickly adjust themselves 

 to the smaller mass of blood, and the original; quanitity of this 

 vital fluid is soon restored (24 to 48 hours) through absorption 

 from the tissues and alimentary canal. The heart beats more 

 rapidly, owing to the lessened resistance in the vessels, and vene- 

 section is accompanied by nausea and prostration. 



The blood is less dense and more fluid after blood-letting, and 

 for this reason, if inflammatory processes follow, exudation is more 

 apt to ensue. The fibrin is first regained, then the normal number of 

 white, and finally that of red corpuscles, in from one to five weeks. 

 Circulatory depressants — as veratrum viride — accomplish much the 

 same results as blood-letting, by causing general reduction of vas- 

 cular tension and relief from local: congestion, thus " bleeding an 

 animal into its own veins " without loss of blood, it is true, but with 

 less rapid and certain effect. 



Cathartics, diuretics and diaphoretics also lower blood pres- 

 sure by abstraction of fluid from the vessels, but their action is slow. 

 The following disorders are those most suitable for treatment by 

 venesection when they exist in an alarming form in robust animals : 



Cerebral congestion. In isolation and 

 tympanitis. 



Apoplexy, particularly parturient apo- 

 plexy of cows. 



Encephalitis. 



Acute cerebral meningitis. 



Active pulmonary congestion and apo- 

 plexy. 



Passive pulmonary congestion in car 

 diac disease. 



Sthenic pneumonia. 

 Sthenic pleuritis. 

 Urticaria. 

 Lymphangitis. 

 Hemoglobinemia. 



( Bacterial, 

 Toxaemia -; Mineral, 



( Vegetable. 

 (Followed by saline infusion.) 



Venesection from the jugular in cerebral congestion, is, in fact, 

 a species of local blood-letting by directly draining blood, away from 

 the brain ; and it preserves life by preventing pressure on, and 

 paralysis of, the great medullary centres controlling the respiration 

 and heart. Moderate blood-letting is sometimes advisable in the 



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