DISEASES FOLLOWING PAETUEITION. 225 



escaped the notice of veterinary writers. I have never examined the 

 blood of a victim of this disease without finding the red-blood 

 globules reduced to little more than one-half their usual size. Now, 

 these globules expand or contract according to the density of the 

 liquid in which they float. If we dilute the blood with water they 

 will expand until they burst, whereas if solids, such as salt or albu- 

 min, are added they shrink to a large extent. Their small size, there- 

 fore, in parturition fever indicates the extreme richness of the blood, 

 or, in other words, plethora. 



Confinement in the stall is an accessory cause, partly because sta- 

 bled cattle are highly fed, partly because the air is hotter and fouler, 

 and partly because there is no expenditure by exercise of the rich 

 products of digestion. 



High temperature is conducive to the malady, though the extreme 

 colds of winter are no protection against it. Heat, however, con- 

 duces to fever, and fever means lessened secretion, which means a 

 plethoric state of the circulation. The heats of summer are, how- 

 ever, often only a coincidence of the real cause, the mature rich 

 pastures, and especially the clover ones, being the greater. 



Electrical disturbances have an influence of a similar kind, dis- 

 turbing the functions of the body and favoring sudden variations in 

 the circulation. A succession of cases of the malady often accom- 

 pany or precede a change of weather from dry to wet, from a low 

 to a high barometric pressure. 



Costiveness, which is the usual concomitant of fever, may in a case 

 ■of this kind become an accessory cause, the retention in the blood of 

 what should have passed off by the bowels tending to increase the 

 fullness of the blood vessels and the density of the blood. 



Mature age is a very strong accessory cause. The disease never 

 occurs with the first parturition, and rarely with the second. It 

 appears with the third, fourth, fifth, or sixth — after the growth of 

 the cow has ceased and when all her powers are devoted to the pro- 

 duction of milk. 



Calving is an essential condition, as the disturbance of the circula- 

 tion consequent on the contraction of the womb and the expulsion 

 into the general circulation of the enormous mass of blood hitherto 

 circulating in the walls of the womb fills to repletion the vessels of 

 the rest of the body and very greatly intensifies the already existing 

 plethora. If this is not speedily counterbalanced by a free secretion 

 from the udder, kidneys, bowels, and other excretory organs, the 

 most dire results may ensue. Calving may thus be held to be an 

 exciting cause, and yet the labor and fatigue of the act are not 

 active factors. It is after the easy calving, when there has been 

 little expenditure of muscular or nervous energy and no loss of 

 blood, that the malady is seen. Difficult parturitions may be fol- 

 33071°— 16 15 



