744 SPORADIC DISEASES. 



The elimination of urea is also influenced by water. The 

 more water an animal drinks the more urea will it excrete. 

 Common salt also produces an augmentation in the excretion of 

 urea. — (Booker, Bischoff.) Certain foods diminish the daily 

 excretion of urea, such as sugar, starch, fat; in fact, says Dr. 

 George Harley, " my idea is that all nitrogenized foods augment, 

 and that all non-nitrogenized foods diminish, the amount of urea 

 eliminated by the kidneys." 



Increased elimination of urea occurs in all febrile diseases, 

 and is indicative of abnormal metamorphosis of tissue ; and its 

 amount bears a close relationship to the exaltation of tem- 

 perature and intensity of fever. Eetention of urea is a very 

 unfavourable circumstance, and is symptomatic of intense con- 

 gestion of the kidneys, exudation and haemorrhage into the 

 uriniferous tubes, and desquamation of their epithelium, with 

 destruction of their secreting cells. 



Uric acid, C^^ H^ N^ 0^, is a white crystalline, feebly acid, 

 tasteless, organic substance, insoluble in ether or alcohol, and 

 but sparingly so in water: 2000 parts of hot and 11,000 parts of 

 cold water are required to dissolve one part of uric acid. It is 

 soluble in strong sulphuric acid, and is transformed by dry dis- 

 tillation into urea, cyanic acid, hydrocyanic acid, carbonate of 

 ammonia, and an oily coal. It unites with bases such as j)otash, 

 soda, or ammonia, forming with them crystalline urates. The 

 urine of herbivorous animals contains little, if any, uric acid ; 

 but it is found in the solid urines of serpents, birds, and insects, 

 and in the liquid urines of omnivora and carnivora, in combina- 

 tion with potash, soda, and ammonia. 



The pathology of uric acid is of little consequence to the 

 veterinarian. It is derived from the same source as urea, and 

 whatever accelerates oxidation increases the amount of urea and 

 diminishes the uric acid, and whatever diminishes oxidation 

 decreases the urea and increases the uric acid in the urine, thus 

 proving that urea is a more completely oxidized product than 

 the uric acid. In the dog and other carnivora uric acid calculi 

 have sometimes been found. 



Hippuric acid (C^g Hg N Oe)is a beautiful white crystalline, 

 slightly acid body, constantly found in the urine of all but the 

 purely carnivorous animal. It is soluble in 400 parts of cold 

 water, and its solution is sufficiently acid to redden litmus 



