316 DIABETES INSIPIDUS. 



rine urine, been termed ' Diabetes Mellitus,' or 'Mellituria;' the 

 otlier a comparatively less serious malady, generally benign in 

 its results, and in which the urine is marked simply by an 

 increase in its watery elements, being known as ' Diabetes 

 Insipidus,' or ' Polyuria.' 



I. Diabetes Insipidus. 



Nature of the Affection. — This in the horse the more impor- 

 tant disorder, because by far the more common, is by many 

 regarded as more truly a functional disorder of the kidneys, 

 and by them placed as a local disease amongst affections of the 

 urinary organs. There are, however, sufficient reasons to 

 warrant its being regarded as something more than this, as 

 intimately related to at least functional disturbance of several 

 of the complex processes in assimilation, and thus correctly 

 viewed as a systemic disorder, and as such we prefer to con- 

 sider it. There seems strong grounds for believing that both 

 these forms, polyuria and mellituria, are merely symptomatic 

 of several, and it may be differing, functional or structural 

 changes ; and that as our knowledge of the causes and condi- 

 tions under which these originate becomes more extensive and 

 more exact, so will our estimate of their relations to each 

 other be liable to vary. This disorder is so common amongst 

 horses operated upon and surrounded by certain influences 

 that, although usually a sporadic affection, it occasionally deve- 

 lops truly enzootic characters. 



Although from the mode of its manifestation, and the 

 character of the symptoms developed during its progress, it is 

 perfectly obvious that several steps in the process of food- 

 assimilation are jjerformed in a faulty manner, and that different 

 organs are involved in the general disturbance, we are unable to 

 determine precisely Avhat organ or set of organs are primarily 

 and chiefly affected, nor at what particular stage in the assimi- 

 latory process, whether in the alimentary canal, in the gland- 

 structures, or in the blood, the interruption is interposed. In 

 all probability the disturbance exists at more than one point, 

 also that more than one organ is functionally perverted. 



Although we may not be able thoroughly to explain its 

 pathology, it is abundantly evident that the disorder consists 

 in more than mere irritation and increased activity of the 



