122 ANNUAL REPORT OF THE Off. Doc. 



and attacks the best milking cows in the herd, those that are in 

 the prime of life, that are in the best of condition and are most 

 profitable. Many of the heaviest milkers in nearly all herds of 

 pure-bred cattle of the dairy breeds have been carried away by 

 this disease. The significance of this fact from the breeder's stand- 

 point is very great, because from tliis cause the breed is deprived 

 of the benefit of the product of many of its most costly and improv- 

 ing members. As an instance: A few years ago the agent of a 

 wealthy breeder of Guernsey cattle, was commissioned to buy the 

 best Guernsey cow that could be found anywhere. A cow that had 

 won a large number of prizes and that was considered the best 

 that could be obtained on the Island of Guernsey w^as had. After 

 she arrived at the owner's farm in this country it was found that 

 she had cost about |5,000. This cow died of milk fever after calving 

 for the first time in this country. The great and far-reaching effect 

 upon a breed of a calamity of this sort can scarcely be estimated, 

 but it is evident that it must be very great. 



The history of the development of knowledge of this disease is 

 most interesting. It has been regarded at different times as a 

 disease of the womb, as a disease of the spinal cord, as a disease of 

 the brain, as a disease of the blood, and now it is known to be 

 caused by the development of an abnormal condition in the udder. 



Any method of feed or care that has the effect of increasing the 

 activity of the udder, predisposes a cow to this disease. It has, for 

 a long time, been known that heavy milking cows in plethoric condi- 

 tion are more likely to be attacked with parturient paresis than 

 are similar cows in low condition. This led some observers to the 

 opinion that plethora is the cause of parturient paresis. This view 

 is not correct, because parturient paresis does not occur in highly 

 nourished cows unless such animals are heavy milkers. The cows of 

 the beef breeds that yield but little milk are not attacked by par- 

 turient paresis, however fat and well nourished they may be at 

 time of calving. It is, therefore, evident that high condition is a 

 cause of parturient paresis only in so far as it tends to stimulate 

 the udder. Cows that have once suffered with paturient paresis 

 and have recovered, are predisposed to a second attack and must 

 be watched with particular care at every calving. 



The postmortem examination of cows dead of parturient paresis 

 is practically negative. There are no lesions that may be said to 

 be characteristic of the disease, and sometimes w^hen death has 

 occurred quickly, postmortem examination is wholly negative. 

 These and other observations gradually led to the opinion that 

 parturient paresis is an intoxication resulting from the absorption 

 of poisonous compounds produced in the udder at the beginning 

 of the period of lactation. It remained for a Danish veterinarian. 



