DIGESTIVE SYSTEM 131 



the accumulation of the precipitate upon the nucleus completes the 

 process. Bits of mucus or any particle of foreign matter may 

 serve as a nucleus. Precipi1;atibn may be caused by supersaturation 

 of the bile with inorganic salts, or it may be A^'s^quel of fermentation 

 of bile. In addition, bacteria and otliei* factors md,y bfe causative 

 agents of calculus formation. 



Infection of the gall-bladder provides the necessary conditions for 

 the formation of gall-stones and is probably the most important 

 cause of their formation. 



Lesions. — Cholelithiasis, or gall-stones, is found most frequently in 

 the gall-bladder. It may occur, hovs^ever, in the hepatic duct or in 

 any of the collecting bile tubes regardless of their size. The presence 

 of gall-tones usually causes obstruction and distention of the gall 

 bladder or of the bile tubes in which they occur. If the obstruction 

 has existed for some time, icterus will usually be more or less pro- 

 nounced. 



Upon opening the gall-bladder or bile duets containing the cal- 

 culi, thick grumose bile escapes and the conerements or calculi are 

 observed. Gall-stones may occur singly, but they are usually multi- 

 ple. They are usually of a brownish-chocolate color and vary in 

 size from mere specks to masses an inch or more in diameter. They 

 may be round or any other shape, and when many are present they 

 are usually faceted when they come into contact with each other. The 

 gall-stones may be composed of organic material entirely and be 

 quite soft or they may be encrusted with mineral matter and be 

 quite hard. Upon sectioning them they are usually found to have 

 been made up in layers, and it is not difficult to distinguish the 

 nucleus. There is an inflammation of the mucous membrane of the 

 gall-bladder or affected bile tubes. 



Sympioms. — Very few if any cases of cholelithiasis have been recog- 

 nized clinically. If the gall-stones obstruct the outflow of bile suf- 

 ficiently there will be general icterus. There are probably some 

 digestive disturbances also. 



Treatment. — The administration of purgatives, especially calomel, 

 is indicated and should be administered regularly in small doses. 

 The treatment will probably not produce permanent relief, but the 

 icteric condition may be overcome by the action of the calomel and 

 the meat made fit for human consumption and the animal can be 

 slaughtered. 



