DIABETES. 499 



Diabetes Mellitus. 



In this disease, an abnormal amount (as much as 5.85 per cent.) 

 of sugar is found in the urine. Friedberger and Frohner state that 

 3.75 per cent, is an average quantity in this complaint. Although 

 only a very few cases have been observed in Europe ; it is not un- 

 common among horses in India. 



NATURE. — The appearance of grape sugar in the urine can be brought 

 about by, among other causes, (1) mechanical irritation by blows and 

 wounds on certain portions of the brain and spinal cord: (2) by drugs that, 

 like morphia and chloroform, excite the brain ; (3) by removal of the 

 pancreas ; and (4) by excessive secretion of grape sugar by the liver (p. 537). 



The presence of sugar may be only a temporary condition, or 

 may be continued, in which case it will be the characteristic 

 symptom of a disease that seems to be almost always fatal in about 

 a couple of months' time. The symptoms, excluding that of the 

 presence of sugar, closely resemble those of diabetes insipidus. 

 Ulceration of the cornea sometimes occurs in the late stages of the 

 disease. Treatment appears to be of no avail. 



Diabetes Insipidus {Polyuria, or Profuse Staling). 



This disease is characterised by a continued and excessive flow of 

 watery urine of low specific gravity, and by consequent thirst. 

 The conditions which give rise to this state, appear to have little 

 or no connection with the well-being of the kidneys'. Irritation to 

 a certain portion of the brain (the rhomboidal sinus near the 

 centre of origin of the pneumo-gastric) is accompanied by profuse 

 staling, though it cannot be exactly explained how this is brought 

 about. It is not improbable that disease germs which are con- 

 tained in musty forage and appear to give rise to polyuria (i.e., 

 much urine), may, after being received into ~ the circulation, 

 manufacture products which irritate the nervous centre in ques- 

 tion. In other cases, the fact of the blood being in an altered 

 condition from disease, errors in diet, etc., may render it liable to 

 encourage the development of ferments or other morbid material, 

 the presence of which in the blood may also disturb the nerves that 

 supply the vessels of the kidneys. Or, the agencies at work, what- 

 ever they may be, may effect their purpose by causing the watery 

 portion Of the blood to escape with undue rapidity. from the arteries 

 of the kidneys. The tendency to dropsy often met with in this 

 disease, seems to favour the view that the fault, at least in some 

 instances, lies in the state of the blood. 



This disease, as a rule, is 'of a mild type. 



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