Occurrence. Etiology. 779 



more generously with the object of increasing the milk production. To- 

 gether with the popularization of the intensive feeding of cows, the cases 

 of disease also increased, and in a like measure from the middle of the last 

 century the number of publications (see etiology) on the subject by veter- 

 inary surgeons in all the civilized countries increased also, without how- 

 ever clearing up the etiology of the disease. In the year 1897 the Danish 

 veterinary surgeon, Schmidt of Kolding published a new theory as to 

 the etiology of milk fever, which did not clear up the cause of the dis- 

 ease, although the treatment based upon it undoubtedly led to a very 

 decided decrease in the losses arising from it. Recently Hess, Sonnen- 

 berg and Delmer have made experiments with the object of clearing up 

 the etiology of the complaint, which is the only correct procedure. 



Occurrence. Milk fever seems to be a disease ahnost ex- 

 clusively confined to cattle, although a few authors (Saint-Cyr, 

 Friedberger & Frolmer, Haubner & Siedamgrotzky, Hoopen) 

 assert that it occurs, rarely, also in goats, sheep and swdne. In 

 certain regions and on individual estates the illness is very fre- 

 ciuent and stands in close relation to the constantly increasing 

 intensity of the agricultural operations (Hess) ; it is conse- 

 quently to be considered as a disease of civilization. Accord- 

 ingly it is met with much more frequently and in a more severe 

 form on farms with choice, succulent food and with first class 

 milk cows, also more often on the outskirts of towns than in dis- 

 tant localities or in the hill country (Hess, Kniisel). 



Etiology. The actual cause of the disease is unknown. 

 This much only is certain that in a great number of cases the 

 inHuenee of certain predisposing factors is manifest in a re- 

 markable manner. 



The breed of the animals has an influence inasmuch as 

 cows of the Holstein breed, which give much milk, are predis- 

 posed to the disease somewdiat less than those of the mountain 

 breeds, and least of all are the range cows, although experiences 

 in Hungary show that the range cattle are not entirely immune 

 from the disease. 



The influence of milk productivity is in so far evident that 

 even in cow^s of the same breed the especially good milker is 

 the one most prone to an attack. 



An essentially predisposing role is played by the age of 

 the cow, the great majority of attacks occurring in the fifth to 

 tenth years of life, that is after the third to fifth calvings, while 

 older cows and such as are under six years of age are attacked 

 only exceptionally. 



Act'ording to statistics collected, by Jeusen iu Denmark out of 931 eases the age 

 of the cows was: in 0.75% of cases 3 years; in 1.82%, 4 years; iu 5.91%, 5 years; 

 in 15.68%, 6 years; in 16%, 7 years; in 19.76%, 8 years; in 10.20%, 9 years; in 

 10.95%, 10 years; in 4.4%, 11 years; in 6.8%, 12 years; and in 7.62%^ more than 12 

 years. 



The course of birth is of considerable significance since 

 after easy births many more cases of illness are recorded than 



