Occurrence, Etiology. 931 



most often, less so pigeons and water fowl (Ziirn), when they 

 are l^ to % year old or even younger. (Haubold observed the 

 disease in eight-weeks-old geese which had been confined for 

 fattening. Blooded and large breeds or such as mature early 

 or grow rapidly are in general more apt to acquire rickets than 

 breeds of animals that are mostly kept out doors and are 

 hardened. Among hogs the disease affects relatively frequently 

 the English breeds and their crossings, among the dogs the 

 Newfoundlands, the Danes and the setters. In animals living 

 in herds, _esp_ecia,lly in pigs and lambs, rachitis usually reaches 

 an enzootic distribution and this causes a very decided economic 

 loss. On the other hand the disease is not observed in wild- 

 living animals. 



Etiology. In the production of rickets in domestic animals 

 the deficiency in lime of the organism is undoubtedly the most 

 important factor. This may be' concluded above all from the 

 fact that the disease commences most frequently in the breeds 

 which mature early, at the time of the most rapid development 

 or after the nursing period is over, that is in that period in 

 which there is most likelihood that the ingestion of lime is 

 insufficient in proportion to the- bony growth. Moreover 

 numerous incontrovertible observations directly established the 

 relation of rickets to food which is poor in lime. Finally a 

 considerable number of positive experimental results in this 

 direction are at hand. 



A deficiency of lime in the organism will probably occur 

 most frequently through an insufficient calcium content in the 

 food. In nurslings rachitis develops, comparatively rarely, 

 through an insufficient calcium content of the mother milk, when 

 the mother animals are nourished with food poor in lime. 

 (According to Dammann healthy young sucking animals become 

 ill if they are put to a mother animal whose young is affected 

 by rachitis.) Moussu observed a similar symptom complex as 

 that seen in rachitis of young pigs in sucking lambs, whose 

 mothers were fed generously with cut carrots, but he looks 

 upon it as an asthenic condition. It happens very rarely that 

 the artificial raising of young animals with alien milk is of 

 importance in this respect, although this milk may become in- 

 jurious in so far as it may contain less lime than the homo- 

 geneous milk, and further the lime salts of such milk may 

 be used up less completely (Uffelmann, Briining) because the 

 presence of alien enzymes may lead to an insufficient assimila- 

 tion of the milk. 



The calcium content of milk varies very considerably in the different animal 



lime and 1.2 gm. of phosphoric acid; and hog's milk, 4.3 gm. of lime and 4.0 

 gm. of phosphoric acid per liter (Stutzer, Kellner), while the corresponding values 

 in dog's milk are 3.01 gm. and 4.11 gm. (Wedemeyer). 



