MERCURIALS 247 



cury with chalk (gray powder). These agents have little if any 

 action on the stomach unless their passage through it is delayed. 

 They are believed to produce their purgative action by mildly irri- 

 tating the intestines with some possible increase in the intestinal 

 secretions, thereby stimulating peristalsis both directly and indirectly. 

 The evacuations from the mercurials are large and loose and 

 may be charged with undecomposed bile. They are not usually ac- 

 companied by much griping but large doses may cause consider- 

 able colic and watery feces, and nausea in some animals. For a 

 long time it was thought that calomel was a distinct chologogue, but 

 later researches show that it serves this purpose only indirectly by 

 moving the aliment away from the bile duct and thus facilitating 

 the discharge of bile into the intestine. 



There is considerable uncertainty concerning the antiseptic ac- 

 tion of calomel in the intestines. It is generally believed that it 

 does not destroy the bacteria or even greatly inhibit their grovrth 

 in the intestines, but does remove great numbers through purgation. 

 Only a small portion of mercurials is absorbed if evacuation 

 is produced quickly, but if there is interference with the passage 

 of the intestinal contents after a large dose of them, diuresis is 

 produced. This interference is occasionally secured by administer- 

 ing morphine or opium with small doses of calomel, but if it occurs 

 after large doses toxic symptoms referable to the irritant action of 

 mercury on the kidneys and other symptoms of mercurialism may 

 result. Consequently some means should be taken to induce purga- 

 tion if the mercurials fail to act unless small doses are given for their 

 diuretic action. 



Calomel acts as a laxative or purgative according to the method 

 of administration and dosage used. It differs from most other 

 purgatives in that its cathartic effect does not increase in a ratio 

 with the dose. Fractional doses repeated at half hour intervals, un- 

 til 1 or 2 grs. (dog) have been taken will produce more purgation 

 than 10 grs. taken at a single dose. 



Therapeutics. Calomel is indicated as a purgative in bilious- 

 ness characterized by coated tongue, foul breath, etc._ It is also 

 especially good to unload the bowels early in an infectious disease, 

 since it unloads the bowels thoroughly and carries out many bacteria. 

 Calomel is often added to the ordinary aloes pill for horses as it 

 is believed to assist the action of aloes. 



Frohner states that it may be abortifacient in canine distemper 

 but most authorities do not agree on this use. 



The other preparations of mercury have similar actions and 

 uses. In veterinary practice, probably calomel is more used in the 

 treatment of the small animals than the large. Pills of Vio grain 

 each of calomel have proved very serviceable in digestive derange- 

 ment of cats (constipation). 



