224 DISEASES OE CATTLE. 



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

 prominent 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. 



The latest developments of treatment indicate very clearly that the 

 main cause is the production of poisonous metabolic products (leuco- 

 mains and toxins) by secreting cells of the follicles of the udder, act- 

 ing on the susceptible nerve centers of the plethoric, calving cow. 

 Less fatal examples of udder poisons are found in the first milk (colos- 

 trum), which is distinctly irritant and purgative, and in the toxic 

 qualities of the first milk drawn from an animal which has been sub- 

 jected to violent overexertion or excitement. Still more conclusive as 

 to the production of such poisons is the fact that the full distention 

 of the milk ducts and follicles, and the consequent driving of the 

 blood out of the udder and arrest of the formation of depraved prod- 

 ucts, determines a speedy and complete recovery from the disease. 

 This does not exclude the other causes above named, nor the influ- 

 ence of a reflex nervous derangement proceeding from the udder to 

 the brain. 



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 of voluntary movement and 

 sensation, indicating a sudden collapse of nervous power; 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 stag- 

 gers; she no longer notices her calf or her food; the eyes appear red 

 and their pupils dilated; the weakness increases and the cow lies 

 down or falls and is thenceforward unable to rise. At this time the 

 pulse is usually full and bounding and the temperature raised, though 

 not invariably so ; the head, horns, and ears being especially hot and 

 the veins of the head full, while the visible mucous membranes of 

 nose and eyes are deeply congested. 



The cow may lie on her breastbone with her feet beneath the body 

 and her head turned sleepily round, with the nose resting on the right 

 flank; or, if worse, she may be stretched full on her side, with even 

 the head extended, though at times it is suddenly raised and again 

 dashed back on the ground. At such times the legs, fore and hind, 

 struggle convulsively, evidently through unconscious nervous spasm. 

 By this time the unconsciousness is usually complete; the eyes are 

 glazed, their pupils widely dilated, and their lids are not moved when 

 the ball of the eye is touched with the finger. Pricking the skin with 

 a pin also fails to bring any wincing or other response. The pulse, 



