260 DISEASES OF CATTKE. 



comes to be a genuine contagious disease, in which the organized fer- 

 ments (bacteria) propagate the aflfection from animal to animal and 

 from herd to herd. More than once I have seen such epizootic diar- 

 7'liea start on the headwaters of a creek, and^ traveling along that 

 stream, follow the watershed and attack the herds supplied with 

 water from the contaminated channel. In the same way the disease, 

 once started in a cow stable, is liable to persist for yeare, or until 

 the building has been thoroughly cleansed and disinfected. It may 

 be carried into a healthy stable by the introduction of a cow brought 

 from an infected stable when she is closely approaching calving. 

 Another method of its introduction is by the purchase of a calf from 

 a herd where the infection exists. 



In enumerating the other causes of this disease we may i-efer to 

 those noted above as inducing indigestion. As a primary considera- 

 tion, any condition which lowers the vitality or vigor of the calf must 

 be accorded a prominent place among factors which, apart from con- 

 tagion, contribute to start the disease de twro. Other things being 

 equal, the strong, vigorous races are the least predisposed to the mal- 

 ady, and in this respect the compact fonn, the healthy coat, the clear 

 eye, and the bold, active carriage are desirable. Even the color of 

 the hair is not unimportant, as in the same herd I have found a far 

 greater number of victims among the light colors (light yellow, light 

 brown) than among those of a darker tint. This constitutional pre- 

 disposition to indigestion and diarrhea is sometimes fostered by too 

 close breeding, without taking due account of the maintenance of a 

 robust constitution, and hence animals that are very much inbred 

 need to be especially observed and cared for unless their inherent 

 vigor has been thoroughly attested. 



The surroundings of the calf are powerful influences. Calves kept 

 indoors suffer to a greater extent than those running in the open air 

 and having the invigorating influences of sunshine, pure air, and 

 exercise ; but close, crowded, filthy, bad-smelling buildings are espe- 

 cially causative of the complaint. The jn-escnce in the air of carbon 

 dioxid, the product of breathing, and of the fetid gaseous products 

 of decomposing dung and urine diminish by about one-fourth of 

 their volume the life-giving oxygen, and in the same ratio hinder 

 the aeration of the blood and the maintenance of vigorous health. 

 "Woi-se than this, such fetid gases are usually direct poisons to the 

 animal breathing them; for example, sulphureted hydrogen (hydro- 

 gen sulphid 2 SH2) and various alkaloids (ptomaines) and toxins 

 (neutral jDoisonous principles) produced in the filth fermentations. 

 These lower the general health and stamina, impair digestion, and 

 by leading to the accumulation in stomach and bowels of undigested 

 materials they lay the foundation for offensive fermentations within 



