248 DISEASES OF CATTLE. 



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 production of milk. 



Calving is an essential condition, as the disturbance of the circulation, 

 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 this malady is seen. Difficult par- 

 turitions may be followed by metritis, but they are rarely connected 

 with parturition fever. 



All these factors coincide in intensifying the one condition of ple- 

 thora, and point to that as the most essential cause of this affection. 

 It is needless to enter here into the much-debated question as to the 

 mode ill which the plethora brings about the characteristic symptoms 

 and results. As the results show disorder or suspension of the nerv- 

 ous functions mainly, it may suffice to say that this condition of the 

 blood and blood-vessels is incompatible with the normal functional 

 activity of the nerve centers. How much is due to congestion of the 

 brain and how much to bloodlessness may well be debated, yet in a 

 closed box like the cranium, in which the absolute contents can not be 

 appreciably increased or diminished, it is evident that apart from drop- 

 sical effusion or inflammatory exudation, there can only be a given 

 amount of blood; therefore, if one portion of the brain is congested 

 another must be proportionately bloodless, and as congestion of the 

 eyes and head generally, and great heat of the head are most promi- 

 nent features of the disease, congestion of the brain must be accepted. 

 This, of course, implies a lack of blood in certain other parts or blood- 

 vessels. 



Symptoms. There may be said to be two extreme types of this dis- 

 ease with intervening grades. In both forms there is the characteris- 

 tic plethora, and more or less sudden loss ot voluntary movement and 

 sensation indicating a sudden collapse of nervous poAver, but in one 

 there is such prominent evidence of congestion of head and brain that 

 it may be called the congestive form, par excellence, without thereby 

 intimating that the torpid form is independent of congestion. 



In the congestive form there is sudden dullness, languor, hanging back 

 in the stall, or drooping the head, uneasy movements of the hind limbs 

 or tail; if the cow is moved she steps unsteadily or even staggers; she 

 no longer notices her calf or her food; the eyes appear red and their 



