DRUGS WHICH ACT ON THE HEART AND BLOOD-VESSELS 457 



Silver. — Only one salt of silver is used in horse practice, and that is the 

 nitrate, or lunar caustic as it is also called. As a weak solution it may be 

 prescribed as a mouth-wash, when a spongy state of the gums indicates the 

 need of a sharp and quickly-acting astringent that will not require frequent 

 repetition, as might be the case if tannin or some of the simpler washes 

 were employed. For the suppression of soft granulations and the forma- 

 tion of a level scab, nitrate of silver is probably the best of all the metallic 

 salts, and is much used in the treatment of broken knees and other skin 

 wounds, when the object in view is to secure the least possible permanent 

 blemish. 



As an eye lotion it is and has been long in repute for a variety of 

 affections of the visual organs. By its effects ujjon the vascular structures 

 of the eye it causes absorption of specks or cloudiness of the cornea if 

 they are not of long standing. In small doses internally administered it is 

 astringent, and occasionally prescribed when ulceration of the stomach or 

 bowels is suspected. 



Bismuth. — As a bowel astringent this drug is valuable either in 

 solution or powder. In the latter form and with chalk it appears to act 

 mechanically by forming a smooth coating over the mucous membrane. 



Chalk, or carbonate of lime, is a safe and often effective astringent in 

 cases of diarrhoea, particularly in those instances in which a general acidity 

 of the intestines gives rise to it. 



DRUGS WHICH ACT ON THE HEART AND 

 BLOOD-VESSELS 



Drugs in this section are conveniently divided into four classes, namely: 

 heart stimulants, heart tonics, heart sedatives, and those which act on the 

 blood-vessels (a) by contracting them, and {b) Ijy relaxing them. 



Disordered blood distribution may be due either to the heart or its 

 blood-vessels acting improperly, or to both. 



In another section the composition of the blood has been described, and 

 the method of its distribution in health; but an animal may possess good 



