DISEASES OF YOUNG CALVES. 253 



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

 rhea 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 years, 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 refer 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 novo. Other things being 

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

 malady, and in this respect the compact form, 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 

 predisposition to indigestion and diarrhea is sometimes fostered by 

 too close breeding, without taking due account of the maintenance 

 of a robust constitution; 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 ; close, crowded, filthy, bad-smelling buildings are especially 

 causative of the complaint. The presence in the air of carbon dioxid, 

 the product of breathing, and of the fetid, gaseous products of decom- 

 posing 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. Worse than this, 

 such fetid gases are usually direct poisons to the animal breathing 

 them; for example, sulphureted hydrogen (hydrogen sulphid 2 SHj) 

 and various alkaloids (ptomaines) and toxins (neutral poisonous 

 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 these organs 

 and consequent irritation, poisoning, and diarrhea. They further 

 weaken the system so that it can no longer resist and overcome the 

 trouble. 



