80 CIRCULATORY STIMULANTS 



Therapeutics. The principal use of digitalis is in the treatment 

 of certain organic affections of the heart. Its use in veterinary 

 medicine is therefore greatly lessened by the fact that horses so af- 

 fected are not only useless for work but absolutely dangerous under 

 the best of treatment, and animals are not usually kept unless there 

 is reason to believe in a permanent cure. However, in functional 

 disorders of the heart, the drug may prove of value although there 

 is no doubt but that its use is overestimated. It is not a rapid acting 

 drug, so should not be depended upon in emergency. 



Its chief uses may be summed up as follows : 



1. Cardiac Tonic and Stimulant. Digitalis is indicated in all 

 diseases of the heart associated with debility or weakness of that 

 organ, characterized by a rapid, weak pulse with low blood pressure 

 (valvular disease, myocarditis, etc.), since it strengthens and regu- 

 lates the heart, prolongs the beat, and procures a longer period of 

 rest for that organ. Blood pressure is raised and consequently con- 

 gestion and its sequellse are relieved. Furthermore, there is increased 

 circulation in the coronary arteries and consequently a better nutri- 

 tion for the heart. In valvular disease it is especially useful since 

 it causes compensation, prevents the reflux of blood, and relieves 

 venous congestion. The indications depend not so much upon the 

 location of the lesion as upon the stage of the disease. It is par- 

 ticularly useful in cases of diminished compensation in cardiac weak- 

 ness with feeble pulse, while in cases of proper compensation it is not 

 only useless but may be detrimental. 



2. Diuretic. Digitalis is one of the most active and persistent 

 diuretics in cardiac disease and therefore very useful in dropsies of 

 cardiac origin. On the other hand, it is of very doubtful value in 

 renal and hepatic dropsies and is of no value at all to remove exudates 

 of an inflammatory nature (pleuritis, peritonitis arthritis or chronic 

 hydrocephalus). 



3.^ Antipyretic. Digitalis is inferior to acetanilid, antipyrin, etc., 

 but single large doses may be of much service in infectious fevers 

 accompanied by heart weakness, as in contagious pleuro-pneumonia 

 of the horse. In such cases Trohner recommends 10 grams (Sijss) 

 for large horses and 5 to 7 grams (.3 ji/4-]%) for small ones. 

 These doses lower the temperature, slow and strengthen the heart, 

 and usually improve the condition of the animal. These large doses 

 are dangerous and should not be repeated. 



4. Pneumonia. Digitalis is frequently indicated in pneumonia 

 since it fills the arteries, relieves congestion, regulates the general 

 circulation and increases the pulmonary circulation. It also fills the 

 coronary arteries and increases -the nutrition of that organ as men- 

 tioned previously. The use of the drug in pneumonia, however, 

 must be entirely governed by the condition of the pulse. If the 

 tension is low, the result of relaxation of the peripheral blood vessels 



