Color due to Foreign Constituents.

Bronze or black color may come from injection of phenic acid.

Deep green or olive green may come from tar, carbolic acid, salol, creosote, or derivatives of benzine taken in.

Brownish green comes from thallin and reddens with iron chloride.

Brown or blood red from rhubarb or senna.

Purple red from santonin, if alkaline (if acid, is reddish yellow).

Red from madder (it is alleged from indigo).

Yellow from carrots.

Blue (indigo blue) may occur in urine of horse or ox when exposed to the air.

Bluish green will come from feeding indigo.

White or yellow color will result from the presence of pus.

White, chylous urine occurs with a hæmatozöon (Bilharzia Crassa) in the blood of cattle.

Translucency. Urine may be passed clear and become turbid by standing. The presence of colloids hinders precipitation and prevents clearing.

Horse: Urine is generally turbid, especially what has been long in the bladder, and that which is last passed. The turbidity is largely due to precipitation of calcium carbonate and bicarbonate, and increases on green food, or if the liquid stands exposed to the air and is cooled. Not unfrequently the salts are thrown down as fine spherical granules, or there may be a white pultaceous mass. They are sometimes entangled in extremely mobile cylindroid masses coming from the uriniferous tubes during convalescence from fevers or during fasting. A fine pellicle on the surface is normal in horse’s urine left in the air.

Ox, Sheep and Goat: Urine is passed clear. May become turbid through the change of lime carbonate into bicarbonate in cattle but always more slowly than in the horse.

Carnivora: Urine is passed clear but becomes turbid on decomposition, or if concentrated. With excess of fat in the food it may become opaque from floating oil globules, apart from the classic chyluria.

Pig: Fed on raw fresh vegetables the urine is clear, but if on cooked or dried vegetables, and especially if nitrogenous, it may show opacity.

Pathological: The horse’s urine is limpid and acid in polyuria; limpid and alkaline or neutral with modified phosphates. It may be morbidly turbid from excess of lime phosphate or sulphate, urea or other acid salts, exudates, leucocytes or pus. These usually indicate nephritis. Mucus and muco-purulent exudate suggest pyelitis or pelvic nephritis. Blood elements indicate nephritis, cystitis or urethritis. Debris of kidney tissue may indicate tuberculosis; tumors, etc.

Turbidity in other animals than solipeds is abnormal: examine the urine.

Consistency of Urine. Morbid urine may be gluey, sizy, syrupy, mucous, oily. If a horse’s urine is scanty a slight siziness may be normal and due to tenacious mucus from the pelvis of the kidney, and from the solution of mucin and epithelium in the alkaline fluid. Viscous, sizy, stringy, and tarry (pitchy) urine is found in pyelitis, pyelo-nephritis, or cystic catarrh, but not in polyuria owing to the presence of the solvent acid.

Odor of Urine. This is somewhat aromatic in horse and ox, disagreeable in the dog, and repulsively heavy in the cat. With polyuria the odor is less. If the urine has been retained and fermented it is ammoniacal, if there are ulcers or tumors it is fœtid, in diabetes it smells of acetone, after taking turpentine it has a violet odor, and after phenic acid, camphor, ether and other drugs it is variously modified.

Specific Gravity of Urine in ratio to water 1000:

Horse,1020to1050(1040)
Ox,1025„1045(1030)
Sheep; Goat,1015„1065(1040)
Dog,1020„1060(1040)
Pig,1005„1015(1010)
Cat,1020„1040(1030)

In the horse the urine may be 1001 to 1010 in polyuria, in chronic interstitial nephritis, and in a crisis of fever attended by diuresis. It may be 1050 to 1060 in glycosuria. Undissolved solids that are merely suspended in the urine do not affect its density.

A rough estimate of solids may be made by multiplying the last two figures of a specific gravity expressed in four figures by 2.33. The result approximates to the number of grammes of solids in 1000 cc.

Chemical Reaction of Urine. The liquid is tested by litmus paper, red and blue, weakly impregnated. The normal reaction is determined by the food: the urine of carnivora and sucking herbivora is acid turning blue litmus red: the urine of vegetable feeders is alkaline turning reds blue. In the horse the alkalinity is mainly due to excess of lime bicarbonate, passing, with standing, into lime carbonate, the carbon dioxide being derived from organic acids (lactic, malic, citric, etc.), by oxidation. The hippurates are also alkaline in reaction. In dogs the acidity is due to lime and soda phosphates, sulphates, urates and oxalates.

Pathologically we find the urine strongly alkaline from the evolution of ammonia from urea, in fermentations occurring with prolonged retention in the bladder or in cystitis. The urine is acid even in herbivora in all fevers in which appetite is lost or seriously impaired, and in which the metabolism is excessive.

Chemical Changes in the Urine in Disease. Sodium Chloride, is present in large amount in health (horse 25 to 35 grammes, dog 0.25 to 5 grammes daily) is diminished in fever, anæmia, visceral and exudative inflammations. It is increased during the absorption of false membranes and exudates. It is thrown down by adding solution of nitrate of silver, the curdy white precipitate being insoluble in nitric acid.

Phosphates of lime, soda, potash and, scantily, of magnesia are normally present (horse 0.08 to 0.60 gramme phosphoric acid daily) and are present in excess in digestive disorders and in malnutrition of bones (rachitis, osteoporosis and rheumatoid arthritis). The alkaline phosphates are very soluble and never precipitated. Earthy phosphates dissolve in acid urine, but are precipitated from alkaline. To a little of the urine add a few drops of acetic acid, followed by a few drops of uranium acetate. A yellow precipitate of uranium and ammonium double phosphate is thrown down.

Indican (C8H7NSO4) is formed from indol which passes successively through the forms of indoxyle and indoxylid potassio-sulphate. This is normally present in the urine, the horse excreting 1 to 2 grammes daily, the dog 0.15 gramme. It is present in excess in intestinal indigestions, constituting indicanuria. It is tested by adding a drop of muriatic acid and one of a solution of chloride of lime to the urine, when it will show a blue ring, the depth of which indicates the relative amount.

Urea (CON2H4) the principal waste product of nitrogenous matter, is always present in considerable amount. The sound horse may eliminate 100 to 200 grammes daily, the dog 5 to 180 grammes. It is present in excess in all fevers and inflammations unless urination is suspended or impaired, in cryptogamic diuresis, in mellituria, uræmia, nephritis and cystitis. Test: The addition to a filtered solution of urine, freed from phosphates, of solution of acid nitrate of mercury, precipitates it as nitrate of urea. A simpler test is to add to a drop or two of urine on a glass slide a drop of nitric acid and heat gently. The nitrate of urea is precipitated in the characteristic rhombic or hexagonal crystals as seen under the microscope. Heat urea crystals in a test tube: biuret is formed and ammonia escapes. Add a trace of a copper sulphate solution and a few drops of a 20 per cent. solution of caustic potash: a rose-red color is produced—the biuret reaction.

Uric Acid (C5H4N4O3). Traces only of this are found in the normal herbivorous urine, yet it is more abundant when on a full dry grain diet, on milk (suckling) or on animal food. The dog kept on animal food has a large amount.

Pathologically it is produced in the dog and even in the horse in fever, overwork and starvation, the animal living on his own tissues. Interference with oxidation in the lungs seems to produce it as an arrest in the transformation of albuminoids to urea. The neutral urate of soda remains in solution: the acid urate of soda is precipitated. Test: To the urine add one-fourth its volume of muriatic acid and set aside for 24 hours in a cool place. On the bottom and sides of the glass and on the surface of the liquid will be found the yellowish red acicular crystals of uric acid.

Hippuric Acid (C9H9NO3) is normally present in all urine, but is especially abundant in that of herbivora. The horse eliminates 60 to 160 grammes daily. It has been found to be increased by feeding on dandelion, carrots, clover, asparagus, apples, plums, benzoic acid, oil of bitter almonds, toluol, cinnamic or kinic acid. It is absent in sucking calves, and horses fed on grain devoid of husk. Pathologically it is increased in hyperthermia, icterus, some liver diseases and diseased kidneys. Test: Precipitate any albumen by nitric acid and boiling, then add hydrochloric acid which precipitates the hippuric acid in long needle-like crystals. Heated in a small glass tube it forms an oily liquid, and heated to redness gives off an odor of hydrocyanic acid (nitro-benzol) and carbon is left. This distinguishes alike from uric acid and benzoic.

Phenol is produced by intestinal fermentation. The horse normally excretes about 3 grammes daily. Pathologically it appears in excess in indigestions, abscesses, softened discharging tubercle, pyæmia, and septicæmia. Test: Dilute solutions of ferric salts give a blue coloration.

Creatinin, a product of metabolism of albuminoids, is found especially in the urine of carnivora and omnivora in health. It is pathologically increased when oxidation is interfered with, as in diseases of the lungs. Test: Add to the urine a very dilute solution of sodium nitro-prusside and then drop by drop some solution of caustic soda, when a ruby red color is shown and disappears again on boiling. Acetic acid changes to blue.

Acetone (C3 H6 O) is found in the urine of healthy omnivora and carnivora and increased by excess of nitrogenous food. Pathologically it has been found in fevers with much blood change, in inanition, in cancer, in indigestions, and auto-intoxications. Test: To several c c. of urine add a few drops of iodo-potassic iodide solution and caustic potash when iodoform will be abundantly precipitated with its characteristic color and odor.

Oxalic Acid (C2 H2 O4) appears to be secreted in small amount by healthy kidneys and it may also come from the splitting up of uric acid after secretion. It is augmented by feeding agents rich in oxalic acid (beets, fresh beans, asparagus, tomatoes). Pathologically it abounds in certain indigestions, and is associated with lameness and emaciation. Test: Add lime water to the urine, and the white oxalate of lime is precipitated.

Allantoin (C4H6N4O3) is found in the urine of sucklings (calves) during the first few weeks of life, in pregnancy and when on a meat diet. It diminishes with the increase of vegetable food.

Xanthin (C5H4N4O2) is found in urine as a result of imperfect oxidation of nitrogenous matters especially, which would otherwise pass into uric or hippuric acid. Its immediate antecedents in such transformation are guanin and hypoxanthin or sarkin. It is a rare constituent of urinary calculus.

Hypoxanthin (C5H4N4O) is produced from fibrine in gastric and pancreatic digestion and in putrefaction, and is especially abundant in leucæmic subjects.

Cyanuric Acid (C20H14N2O6) occurs in dog’s urine.

Leucin (C6H13NO2) and Tyrosin (C9H11NO3) are products of pancreatic digestion of proteids, and the former occurs normally in the spleen, thymus, thyroid, liver, salivary glands, and urine. Both are present in large amount, in the urine, in acute atrophy of the liver. Test for leucin: Evaporate carefully to dryness with nitric acid: the residue, if leucin, will be almost transparent and turn yellow or brown on the addition of caustic soda. If now heated with the soda it forms an oily drop. Test for tyrosin: treated with strong sulphuric acid, gently warmed and chloride of iron added, it gives a violet color.

Albumen is an important morbid constituent of urine, which appears in a great variety of diseases (nephritis, pneumonia, epilepsy, anæmia, leucæmia, diabetes, hæmaturia, hæmoglobinuria, hydræmia, infectious lung diseases, cardiac obstruction, venous stasis in the kidney, dermatitis, burns, lesions of the crura cerebri, floor of the fourth ventricle, spinal cord, or renal vaso-motor nerves). It also occurs after violent exertion, in poisoning by strong acid, phosphorus, arsenic, lead, mercury, opium or alcohol, and when an excess of albumen is injected into the blood. All forms of albumen may enter the urine, but the most common are serum albumen, globulin of serum, propeptone and peptone. A simple test is to acidulate the urine with acetic acid and boil: if the precipitate does not dissolve on addition of nitric acid, it is albumen. Sulphosalicylic acid added to the urine will cause a precipitate in urine containing only ¹⁄₅₀₀₀₀ of albumen.

Glucose (C6H12O6) is often normally present for a short period in small amount after a full meal of farinaceous material. It is permanently present in excess in glycosuria, which may result, among other conditions, from diseased liver, punctured medulla, suppression of milk secretion on weaning the calf, oil of turpentine, nitrobenzole, nitrotoluol or amyle nitrate. Test: Add yeast to the urine and keep at 15° to 20° C. when if glucose is present, it becomes cloudy and gives off carbon dioxide, or add a little caustic potash solution, and a few drops of cupric sulphate solution until it is blue: then heat and a red precipitate of cupreous oxide is thrown down. The amount gives the ratio of glucose. Uric acid, hypoxanthin or mucus causes brown precipitate in the absence of glucose: peptone, creatin, creatinine, pepsine and urinary pigment prevent its formation though glucose be present.

Bile Salts and Pigments are present in excess in cases of icterus, where these characters may be studied. See Icterus.

Blood and Hæmoglobin in Urine. In a variety of diseases (anthrax, hæmaturia, nephritis, Texas fever, hæmoglobinuria, etc.) blood or blood coloring matter escapes in the urine. When blood escapes one finds the reddish color, and under the microscope red globules, normal or crenated (especially in alkaline urine), free, aggregated in masses, in small clots, or embedded in casts of the uriniferous tubes. Under the spectroscope the spectrum shows two dark absorption bands, one in the yellow and one in the green. When the color is due to hæmoglobin the urine shows under the microscope numerous masses of amorphous brown pigment, and the spectrum shows one dark line in the yellow, and three others less deep, (but one of them very broad) on the limit of the green and blue. Urine which contains the elements of blood is usually turbid and thick or glairy, by reason of the presence of salts, albumen and fibrine. There may also be crystals of urinary salts (calculi), fragments of broken down tissue (tumors) or the ova of worms.

Epithelium in Urine. The slight cloud seen in healthy urine contains epithelial cells. The source of these may be often determined under the microscope. The bladder epithelium are the most numerous, the largest, and are squamous. Those from the ureters and renal pelvis are also squamous, but neither so large nor so numerous. The epithelium from the uriniferous tubules are polyhedral with large nucleus or columnar. The cells from the male urethra are also largely columnar. In cases, however, in which these cells are passed in large amount because of catarrh of the mucosa all alike tend to assume the globular form with large nucleus so that their true source cannot be certainly stated. It is only from such cells as have become detached without change of form that the seat of desquamation can be determined. If an excess of cells approximating to the kidney type are associated with albuminuria and cylindroid casts they become diagnostically significant. Polygonal cells darkly granular with large oval nucleus and nucleolus suggest kidney inflammation. If the granules are freely soluble in ether there is probably fatty degeneration. If hard, tough and glossy they suggest (but don’t prove) amyloid degeneration.

Pus Cells in Urine. Pus cells, with multiple nuclei revealed by adding dilute acetic acid, may be found in small numbers in apparently healthy urine. When present in large numbers, they usually indicate a catarrhal affection of the mucosa, and especially pyelitis, cystitis, or urethritis. There is always cloudiness, excess of mucin, and, in the alkaline herbivorous urine, the liquid may be glairy or stringy.

Casts of the Uriniferous Tubes. These usually indicate the existence of nephritis, yet they may be present in small numbers in the urine of healthy individuals under a slight toxic action such as alcohol.

Unorganized casts of urinary salts or hæmatoidin found in sucklings appear to have no pathological significance. Organized casts, on the other hand, usually imply renal troubles, and especially inflammation. As these will be fully described under Bright’s disease, it need only be noted here that they may be composed in great part of red globules, leucocytes, epithelium, bacteria, granules, a homogeneous wax-like matter, fat globules, hyaline matter, or urinary salts. The predominance of one or other of these determines the nature of the cast.

The observations of Mayer, Knoll, Bovida, Von Jaksch and others seem to show that the basis substance of urinary casts differs from all our familiar proteids and must be considered as a distinct nitrogenous compound, a derivative of one of the common proteids.