DISEASES FOLLOWING PARTUEITION. 229 



crease of 2 to 3 pounds of body weight, mainly fat. The victims are 

 not always fat when attacked, but they are cows having enormous 

 powers of digestion, and which have been fed heavily at the time. 

 Hence the stall-fed, city dairy cow, and the farm cow on a rich clover 

 pasture in June or July, are especially subject. The condition of the 

 blood globules in the suffering cow attests the extreme richness and 

 density of the blood, yet this peculiarity appears to have entirely 

 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. 



G onfjiwinent in the stall is an accessory cause, partly because stabled 

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

 partly because there is no expenditure by exercise of the rich prod- 

 ucts of digestion. 



High temperature is conducive to the malady, though the extreme 

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

 to fever, and fever means lessened secretion, wliich means a plethoric 

 state of the circulation. The heats of summer are, however, often 

 only a coincidence of the real cause, the mature rich pastures, and 

 especially the clover ones, being the gi*eater. 



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

 ing the functions of the body and favoring sudden variations in the 

 circulation. A succession of cases of the malady often accompany or 

 precede a change of w^eather 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 produc- 

 tion 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 



