DOSES AND PREPARATIONS 541 



endocarditis, occurring occasionally in cattle, it renders the 

 heart-beat more regular, and gives fulness to the small 

 thready pulse. Digitalis, though often given, should not 

 be advised in cases of internal haemorrhage, for the increased 

 flow of blood from the heart and the rise of blood-pressure 

 tend to increase the bleeding. 



In equine pneumonia, especially in the second stages, 

 digitalis frequently relieves engorgement, probably by pro- 

 pelling blood in fuller stream into the abdominal and other 

 vessels. Promoting circulation, it moreover aids oxygena- 

 tion of blood, and hence is also useful in congestion and pur- 

 pura. It is a frequent constituent of cough mixtures. 



Digitalis relieves many cases of dropsy by regulating 

 faulty heart-action, stimulating dilated arterioles, as well 

 as by inducing diuresis. In pleuritic effusion, Robertson 

 gave horses digitalis, grs. xx. to grs. xxx. ; potassium 

 nitrate, 3^J- 5 powdered cantharides, grs. iv. to grs. x., 

 made into bolus, and repeated twice daily for a week. 

 Diuresis is determined by prescribing digitalis with salines 

 a combination often useful in cardiac dropsy. 



The chief indications for the use of digitalis are an 

 enfeebled, irritable, jerking, or irregular heart, deficient 

 arterial pressure, venous engorgement, and scanty secretion 

 of urine. Under its influence the pulse gains force and 

 amplitude, respiration becomes less difficult, and urination 

 is increased. It is more suitable for chronic than acute 

 cases. As with other tonics, it is best tolerated in those 

 weak and irritable states of the heart in which it is most 

 serviceable. It is of little use in difficulty of breathing 

 or dropsical conditions chiefly dependent on lung disease. 

 It does harm in aortic disease or in hypertrophy, where the 

 pulse continues strong, firm, and regular ; or in enfeebled 

 circulation dependent on advanced fatty degeneration. 

 Nausea or irritability of the digestive organs, coldness of 

 the extremities, unwonted force of the pulse-beats, indicate 

 that the medicine should be stopped, or given in reduced 

 amount. The effects of overdoses are combated by alcohol 

 or other stimulants, injections of ether or strychnine ; 

 emetics and purgatives ; and by keeping the patient per- 

 fectly quiet. 



