348 DISEASES OF METABOLISM 



ing the convalescent stage of acute diseases (distemper). (&) 

 Accompanying diseases of the nervous system, such as 

 tumors of the brain, lesions of the medulla, cerebral hemor- 

 rhage, inflammation of the membranes of the brain or spinal 

 cord, (c) Subjection to cold; drinking large quantities of 

 cold water have been thought to cause the disease, (d) 

 Trauma of the liver; vertebral column, (e) The administra- 

 tion of diuretics either when given in large doses or con- 

 tinued over a long period of time in small doses will produce 

 it. (/) There is a possibility that the disease is of infectious 

 origin; however, this has never been proved. 



The production of diabetes insipidus is no doubt due to 

 a vasomotor disturbance of the renal vessels resulting in a 

 great increase in the secretion of urine. The above men- 

 tioned conditions lead to this disturbance through direct 

 irritation, or to functional irritation of the center in the 

 medulla, which brings about a constant state of renal con- 

 gestion. 



Pathology. The necropsy findings are unimportant in the 

 majority of cases. Quite often very slight or no changes in 

 the tissues are found. In some cases the kidneys are enlarged 

 and hyperemic. Dilation of the ureters and pelvis of the 

 kidneys is occasionally seen. Certain changes will also 

 be found in the nervous system, liver and lungs. The 

 musculature is pale and anemic in advanced cases. 



Symptoms. The disease may come on suddenly resulting 

 from irritation to the nervous system or kidneys, or it may 

 be gradual in its development. In rabbits it may develop 

 suddenly after feeding mouldy food, etc. Many cases are 

 not observed until the symptoms of anemia and general 

 cachexia are present. Two very prominent symptoms are: 

 (a) Copious secretion of urine; (6) intense thirst. 



(a) A large quantity of urine is passed each day; in dogs 

 as much as two to four liters in twenty-four hours, and in 

 rabbits one-fourth the quantity. The urine has a low 

 specific gravity (1.001 to 1.003), is colorless, almost odorless, 

 and voided without any difficulty except when the condition 

 is accompanied by a catarrhal inflammation of the mucous 

 membrane of the urethra or bladder. The urine contains 



