154 DISEASES OF CATTLE. 



working oxen wliich are called upon to exhale more water from the 

 lungs and skins than are the slop-fed and inactive cows. Little water 

 being introduced into the body with the food, and a considerable 

 amount being expelled with the breath and perspiration in connection 

 with the active life, the urine becomes small in amount, but having to 

 carry out all waste material from the tissues and the tissue-forming 

 food, it becomes so charged with solids that it is ready to deposit them 

 on the slightest disturbance. If, therefore, a little of the water of such 

 concentrated urine is reabsorbed at any point of the urinary passages, 

 the remainder is no longer able to hold the solids in solution, and they 

 are at once precipitated in the solid form as gravel or commencing 

 stone. In cattle, on the other hand, which are kept at pasture in sum- 

 mer, or which are fed liberally on roots, potatoes, pumpkins, apples or 

 ensilage in winter, this concentrated condition of the urine is not in- 

 duced, and under such circumstances, therefore, the formation of stone 

 is practically unknown. Nothing more need be said to show the con- 

 trolling influence of dry feeding in producing gravel and of a watery 

 ration in preventing it. Calculus in cattle is essentially a disease of 

 winter, and of such cattle as are denied succulent food and are confined 

 to dry fodder as their exclusive ration. "While there are exceptions, 

 they are so rare that they do not invalidate this general rule. It is 

 true that stone in the kidney or bladder is often found in the summer 

 or in animals feeding at the time on a more or less succulent ration, 

 yet such masses usually date back to a former period when the animal 

 was restricted to a dry ration. 



In this connection it should be noted that a great drain of water 

 from the system, by any other channel than the kidneys, predisposes 

 to the production of gravel or stone. In case of profuse diarrhea, for 

 example, or of excessive secretion of milk, there is a corresponding 

 diminution of the water of the blood, and as the whole amount of the 

 blood is thus decreased, and as the quantity of urine secreted is largely 

 influenced by the fulness of the blood vessels and the pressure exerted 

 upon their walls from within, it follows that with this decrease of the 

 mass of the blood and the lessening of its pressure outward, there 

 will be a corresponding decrease of urine. The waste of the tissues, 

 however, goes on as before, and if the waste matter is passed out 

 through the kidneys it must be in a more concentrated solution, and 

 the more concentrated the urine the greater the danger that the solids 

 will be deposited as small crystals or calculi. 



Again, the concentrated condition of the urine which predisposes to 

 such deposits is favored by the quantity of lime salts that may be 

 present in the water drunk by the animal. Water that contains 20 or 

 30 grains of carbonate or sulphate of lime to the gallon must con- 

 tribute a large addition of solids to the blood, and urine as compared 

 with soft waters from which lime is absent. In this connection it is a 

 remarkable fact that stone and gravel in the domesticated herbivora 



