RETROGRESSIVE TISSUE CHANGES. 205 



Physiologic Fatty Changes. 



(Fatty Infiltration.) 



Physiologic fatty changes is a condition in which there is an 

 excessive accumulation of fat, but the function of the affected 

 part is not materially changed. 



Etiology. Excess Food.— House dogs and cats and many family 

 horses are usually fed to excess, resulting in the tleposition of exces- 

 sive quantities of fat in practically all tissues, thus producing general 

 obesity. The "Strassburg goose" is force-fed with dough balls 

 in excessive quantities until excessive obesity is produced, the 

 liver especially becoming the seat of marked fatty accumulations. 

 In fact all prime "butcher stuff" is aft'ected with physiologic fatty 

 changes or dietary obesity. 



Insufficient Exercise. — Animals kept in tie stalls or in close 

 quarters have a tendency to become excessively fat, especially if 

 they are fed a full ration, because there is diminished oxidation 

 on account of lack of exercise and the bulk of the consumed food 

 is stored as fat. 



Venesection. — Frequent bleeding diminishes the percentage of 

 red ])lood corpuscles and tlius indirect!}' diminished oxidation 

 and favors fat accumulation. 



Disease. — Some diseases appear to influence the physiologic 

 deposition of fat. The early stages of tuberculosis in cattle and 

 hogs and distomatosis in sheep is accompanied l)y [physiologic 

 fatty deposition. During convalescence from some diseases there 

 is an increased deposition of fat. 



Lactation. — The early period of lactation is accompanied bv 

 fatty accumulation especially in the liver. (Possibly the liver 

 may act as a distributing center of fat.) The fatty accumulation 

 in the liver is evident regardless of any variations in the composi- 

 tion of food stuff. 



Heredity. — Some animals, especially hogs, except the Tamworths 

 and Yorkshires, appear to have an inherent tendencv to become 

 excessively fat. 



Castration.- — Removal of the g&nital glands favors fat accumula- 

 tion in the tissues. Castrated dogs and cats, especially if cas- 

 trated when mature, become obese. 



In general the exciting causes of physiologic fatty changes 

 are excess of food or diminished oxidation, heredity being a pre- 

 disposing factor. 



