The _urine_ is usually scanty, high colored, of a high specific gravity and is passed often with pain and groaning. At the outset of an acute attack it may be bloody; later it may be only cloudy or turbid from the excess of epithelial and pus cells, leucocytes, salts and albumen. Early in the disease the casts may contain red blood cells, and renal epithelium, later leucocytes, nuclei, granules, pus cells, crystals and other matters. Albumen is usually abundant as demonstrated by boiling and nitric acid. _Soda carbonate crystals_, rhomboid, rosette-shaped or spherical and effervescing with acetic acid, abundant in normal herbivorous urine may be greatly reduced or absent in nephritis. =Soda oxalate crystals=, tetrahedral and insoluble in acetic acid, and normal in herbivora and carnivora, are increased if the urine is acid as in severe nephritis, but also in rheumatism, tetanus, septicæmia, angina, heaves, and other affections with defective æration of the blood. =Ammonio-magnesian phosphate crystals=, rhomboid but insoluble in acetic acid, are found in alkaline (ammoniacal) or neutral urine, and appear to be often due to intestinal fermentations. _Cystine crystals_, flat hexagonal plates, precipitated in healthy urine, but dissolved by ammonia are absent in retained and fermented specimens. =Uric acid crystals=, rhomboids and plaques, brick red, and normal in the urine of carnivora and flesh-fed omnivora, may be present in herbivora not only in acute nephritis, but in other extensive inflammations attended with anorexia and the consumption of the animal tissues. =Hippuric acid crystals=, right rhombic prisms and their derivatives, and insoluble in hydrochloric acid or ether, are greatly increased in all febrile diseases in herbivora, nephritis included. =Hæmatoidin crystals=, fine needles or bundles of the same, yellowish red, are found in nephritis, hæmaturia, heaves, etc. =Epithelium, if columnar=, points to disease of the kidney tubes, though very similar cells are derived from the urethra in both male and female. Squamous epithelium points to the cystic mucosa and is not increased in nephritis. =Mucus= in cylindroid form may point to nephritic congestion or inflammation, but this may be present in health, and may show in irregular masses derived from the renal pelvis or the bladder. Mucous casts are always extremely elastic and mobile, and lack the even clear cut margins of the casts of nephritis. They are much more common in horses urine than in that of other animals.