- ,. ' DISEASES OF CATTLE 193 



of escape and immediately becomes stored up in the glands and in 

 the blood, throwing the system into a high state of plethora. Now, 

 at the time of calving all the blood which has been supplying the 

 fetus is suddenly thrown back on the circulation, and if the udder 

 does not begin active secretion very promptly plethora 'becomes ex- 

 treme. The blood plasma under these conditions is very rich and 

 dense, containing a large percentage of albumen and glycogen, and 

 causing a shrinkage in size of the blood cells. This condition is 

 invariably seen when the blood of milk-fever patients is examined 

 under the microscope. 



Fatness of the animal has been ascribed an important place 

 among the causes of milk fever. This, however, in itself is probably 

 not a predisposing cause. The beef breeds (Angus and Shorthorn) 

 are usually in far better condition at the time of calving than the 

 milking breeds (Jersey and Holstein), and yet milk fever is a rarity 

 in the former. At the same time it must be understood that a fat 

 Jersey is more predisposed than one poor in flesh. In the fat Jersey 

 the system is already loaded with an excess of nutriment, and, at the 

 time of calving, extreme plethora is more readily produced than in 

 the thin animal where the excess of nutritive elements could be more 

 readily used and stored in the depleted muscular and glandular 

 structures of the body. Fatness is therefore only of importance in the 

 production of the disease in so far as it tends to increase glandular 

 activity, particularly of the udder, and because of the higher state 

 of plethora of the fat animal. i 



Symptoms. This disease in its typical and most common form 

 is comparatively easy to diagnose and one which almost every dairy- 

 man knows immediately before the arrival of the veterinarian. It 

 usually comes on within two days after the birth of the calf and is 

 practically never seen after the second week. In isolated instances 

 it has been observed a few days before calving. At the commence- 

 ment of the attack there is usually excitement; the cow is restless, 

 treads with the hind feet, switches the tail, stares anxiously around 

 the stall or walks about uneasily. She may bellow occasionally, show 

 slight colicky symptoms, and make ineffectual attempts at relieving 

 the bowels. These symptoms are rarely recognized by the owner, but 

 they are followed within a few hours by beginning paralysis, indi- 

 cated by a staggering gait, especially in the hind legs, and by weak- 

 ening of the knees and fetlocks in front. The patient now becomes 

 quieter, the gait more staggering and weak, and finally the animal 

 goes down and is unable to rise. The paralysis by this time is gen- 

 eral, the calf is unnoticed, and the cow lies perfectly quiet with the 

 eyes partly closed and staring and showing a complete absence of 

 winking when the eyeball is touched. She is absolutely unheedful 

 of her surroundings and flies may alight with impunity on all parts 

 of the body without causing the slightest movement to dislodge them. 

 While down the patient assumes a very characteristic position, which 

 is of great aid in diagnosis. The head is turned around to the side 

 (usually the left) and rests on the chest, causing a peculiar arching 

 of the neck. If the head is drawn out straight, it immediately flops 



