392 CHAPTER 56. 



line, soapy fluid. From the liver the bile passes directly into the intes- 

 tines. The horse is not furnished, as are many other animals, with a 

 gall-bladder. 



Unlike most secretions, bile is elaborated chiefly from the venous blood. 

 Mixing with the partially digested food, it hastens its solution, and adapts 

 it for absorption into the system. By some it is thought also to stimu- 

 late the intestinal linings to increased secretion of their solvent fluids. 

 The bile poured into the intestines is nearly all taken up again by the 

 absorbents before the fasces arrive at the anus. 



The secretion of the Liver is increased by rich abundant food, by 

 indolence, by heated stables, also by mercury, any preparation of 

 ammonia, mineral acids, and by purgatives generally. Conversely it is 

 diminished by light diet, strong exercise in the open air, cool stables, 

 compounds of iodine administered internally, and by carbonate of soda 

 given whilst the process of digestion is going on. 



806. Diseases of the Liver. 



The Liver, though subject to frequent derangement in man and also in 

 some of the lower animals, is comparatively seldom diseased functionally 

 or organically in the horse. 



Its diseases may be divided into two classes, namely, temporary func- 

 tional derangements, such as inactivity, congestion, and inflammation ; 

 and secondly, organic structural changes, such as enlargement, atrophy, 

 softening, and induration. The first named ordinarily result from pre- 

 ventible causes, such as excess of food, want of proper exercise, or expo- 

 sure to vicissitudes of temperature or weather. The latter are seldom 

 primary affections ; but as a general rule result from other diseases, such 

 as influenza, inflammation of the lungs and pleurae, etc. 



807. Causes of temporary Functional Derangements. 



Inactivity, often followed by. congestion, is frequently caused by excess 

 of food, especially if it be of a stimulating character combined with in- 

 sufficient exercise. The liver becomes loaded with bile, and this condi- 

 tion is afterwards succeeded by a diminution of the quantity of this secre- 

 tion formed in the hepatic cells. This is in conformity with the usual 

 rule of nature that, when any organ is put to excessive use for a time, 

 reaction follows. The horse then becomes hide-bound and debilitated. 

 In many cases the appetite falls oft 7 , but in others the patient may feed 

 even ravenously. He will not however thrive until the organ again re- 

 sumes its normal function.. Congestion may also be brought on by a 

 sudden chill or exposure. In London and other large towns it is very 

 prevalent in densely foggy weather, owing to the systemic depression 

 thereby produced and the impurity of the blood from its imperfect revivi- 

 fication in the lungs. 



A state of passive congestion may exist for a length of time without 

 any very noticeable symptoms. On the other hand inflammation may 

 supervene on the congestion, whether arising from previous inactivity, or 



