76 DISEASES OF THE HORSE. 



the urine; of an excess of hippuric acid and allied products, which 

 being less soluble than urea (the normal product of tissue change), 

 favor the formation of stone, of taurocholic acid, and other bodies 

 that tend, Avhen in excess, to destroy the blood globules and to cause 

 irritation of the kidneys by the resulting hemoglobin excreted in the 

 urine, and of glycogen too abundant to be burned up in the system, 

 which induces saccharine urine (diabetes). Any disorder leading to 

 impaired functional activity of the lungs is causative of an excess of 

 hippuric acid and allied bodies, of oxalic acid, of sugar, etc., in the 

 urine, which irritate the kidneys even if they do not produce solid 

 deposits in the urinary passages. Diseases of the nervous system, 

 and notably of the base of the brain and of the spinal cord, induce 

 various urinary disorders, prominent among which are diabetes, 

 chylous urine, and albuminuria. Certain aifections. with imperfect 

 nutrition or destructive waste of the bony tissues, tend to charge the 

 urine with phosphates of lime and magnesia, and endanger the forma- 

 tion of stone and gravel. In all extensive inflammations and acute 

 fevers the liquids of the urine are diminished, wliile the solids (waste 

 products), which ^-hould form the urinary secretion, are increased, 

 and the surcharged urine proves irritant to the urinary organs or the 

 retained waste products poison the system at large. 



Diseases of the heart and lungs, by interfering with the free onward 

 flow of the blood from the right side of the heart, tend to throw that 

 liquid back on the veins, and this backward pressure of venous blood 

 strongly tends to disorders of the kidneys. Certain poisons taken 

 with the food and water, notably that found in magnesian limestone 

 and those found in irritant diuretic plants, are especially injurious to 

 the kidneys, as are also various cryptogams, whether present in musty 

 hay or oats. The kidneys may be irritated by feeding green vege- 

 tables covered with hoar frost or by furnishing an excess of food rich 

 in phosphates (wheat bran, beans, pease, vetches, lentils, rape cake, 

 cotton-seed cake) or by a privation of water, which entails a concen- 

 trated condition and liigh density of the urine. Exposure in cold 

 rain or snow storms, cold drafts of air, and damp beds are liable to 

 further disorder an already overworked or irritable kidney. Finally, 

 sprains of the back and loins may cause bleeding from the kidneys or 

 inflammation. 



The right kidney, weighing 23^ ounces, is shaped like a French 

 bean, and extends from the loins forward to beneath the heads of the 

 last two ribs. The left kidney (Plate IV) resembles a heart of cards, 

 and extends from the loins forward beneath the head of the last rib 

 only. Each consists of three distinct parts— (a) the external (corti- 

 cal), or vascular part, in Avhich the blood vessels form elaborate 

 capillary networks within the dilated globular sacs which form the 

 beginnings of the secreting (uriniferous) tubes and on the surface 



