The specific gravity of the urine of cattle varies from 1,030 to 1,060 in health, water being 1,000. It is transparent, with a yellowish tinge, and has a characteristic, musky smell. The chemical reaction is alkaline, turning red litmus paper blue. The quantity passed in twenty-four hours varies greatly, increasing not only with the water drunk, but with the albuminoids taken in with the feed and the urea produced. If a solution of urea is injected into the veins the secretion of urine is greatly augmented. Similarly the excess of salts like carbonate of potash in the feed, or of sugar, increases the action of the kidneys. Only about 20 per cent of the water swallowed escapes in the urine, the remaining 80 per cent passing mostly from the lungs, and to a slight extent by the bowels. The skin of the ox does not perspire so readily nor so freely as that of the horse; hence the kidneys and lungs are called upon for extra work. The influence of an excess of water in the feed is most remarkable in swill-fed distillery cattle, which urinate profusely and frequently, yet thrive and fatten rapidly.
Among the other conditions that increase the flow of urine is overfilling of (internal pressure in) the blood vessels of the kidneys; hence the contraction of the blood vessels of the skin by cold drives the blood inward, tends to dilate the blood vessels of the kidneys, and to increase the secretion of urine. Nervous disorders, such as excitement, fear, congestions, or structural injuries to the back part of the base of the brain, have a similar result, hence, doubtless, the action of certain fungi growing in musty hay or oats in producing profuse flow of urine, whereas other forms of musty fodder cause stupor, delirium, or paralysis. Bacteria and their products are mainly expelled by the kidneys, and become sources of local infection, irritation, and disease.
The quantity of urine passed daily by an ox on dry feeding averages 7 to 12 pints, but this may be increased enormously on a watery diet.
The mutual influence of the kidneys and other important organs tends to explain the way in which disease in one part supervenes on preexisting disorder in another. The introduction of albuminoids in excess into the blood means the formation of an excess of urea, and a more profuse secretion of urine, of a higher specific gravity, and with a greater tendency to deposit its solid constituents, as gravel, in the kidneys or bladder. A torpid action of the liver, leaving the albuminoids in transition forms, less soluble than the urea into which they should have been changed, favors the onset of rheumatism or of nervous disorder, the deposit of such albuminoid products in the kidneys, the formation of a deep-brown or reddish urine, and congestion of the kidneys. Any abnormal activity of the liver in the production of sugar—more than can be burned up in the circulation—overstimulates the kidneys and produces increased flow of a heavy urine with a sweetish taste. This increased production of sugar may be primarily due to disease of the brain, which, in its turn, determines the disorder of the liver. Disease of the right side of the heart or of the lungs, by obstructing the onward flow of blood from the veins, increases the blood pressure in the kidneys and produces disorder and excessive secretion. Inactivity of the kidneys determines an increase in the blood of waste products, which become irritating to different parts, producing skin eruptions, itching, dropsies, and nervous disorders. Sprains of the loins produce bleeding from the kidneys and disease of the spinal cord, and sometimes determine albuminous or milky looking urine.
The kidney of the ox ([Pl. IX], fig. 1) is a compound organ made up of 15 to 25 separate lobules like so many separate kidneys, but all pouring their secretion into one common pouch (pelvis) situated in an excavation in the center of the lower surface. While the ox is the only domesticated quadruped which maintains this divided condition of the kidney after birth, this condition is common to all while at an early stage of development in the womb. The cluster of lobules making up a single kidney forms an ovoid mass flattened from above downward, and extending from the last rib backward beneath the loins and to one side of the solid chain of the backbone. The right is more firmly attached to the loins and extends farther backward than the left. Deeply covered in a mass of suet, each kidney has a strong outer, white, fibrous covering, and inside this two successive layers of kidney substance, of which the outer is that in which the urine is mainly separated from the blood and poured into the fine, microscopic urinary ducts. ([Pl. X], fig. 1) These latter, together with blood vessels, lymph vessels, and nerves, make up the second, or internal, layer. The outer layer is mainly composed of minute globular clusters of microscopic, intercommunicating blood vessels (Malpighian bodies), each of which is furnished with a fibrous capsule that is nothing else than the dilated commencement of a urine tube. These practically microscopic tubes follow at first a winding course through the outer layer (Ferrein's tubes), then form a long loop (doubling on itself) in the inner layer (Henle's loop), and finally pass back through the inner layer (Bellini's tubes) to open through a conical process into the common pouch (pelvis) on the lower surface of the organ. ([Pl. X], figs. 1, 2, 3.)
The tube that conveys the urine from the kidney to the bladder is like a white, round cord, about the size of a goose quill, prolonged from the pouch on the lower surface of the kidney backward beneath the loins, then inward, supported by a fold of thin membrane, to open into the bladder just in front of its neck. The canal passes first through the middle (muscular) coat of the bladder, and then advances perceptibly between that and the internal (mucous) coat, through which it finally opens. By this arrangement in overfilling the bladder this opening is closed like a valve by the pressure of the urine, and the return of liquid to the kidney is prevented. The bladder ([Pl. IX], fig. 2) is a dilatable, egg-shaped pouch, closed behind by a strong ring of muscular fibers encircling its neck, and enveloped by looped, muscular fibers extending on all sides around its body and closed anterior end. Stimulated by the presence of urine, these last contract and expel contents through the neck into the urethra. This last is the tube leading backward along the floor of the pelvic bones and downward through the penis. In the bull this canal of the urethra is remarkable for its small caliber and for the S-shaped bend which it describes in the space between the thighs and just above the scrotum. This bend is attributable to the fact that the retractor muscles are attached to the penis at this point, and in withdrawing that organ within its sheath they double it upon itself. The small size of the canal and this S-shaped bend are serious obstacles to the passing of a catheter to draw the urine, yet by extending the penis out of its sheath the bend is effaced, and a small, gum-elastic catheter, not more than one-fourth of an inch in diameter, may with care be passed into the bladder. In the cow the urethra is very short, opening in the median line on the floor of the vulva about 4 inches in front of its external orifice. Even in her, however, the passing of a catheter is a matter of no little difficulty, the opening of the urethra being very narrow and encircled by the projecting membranous and rigid margins, and on each side of the opening is a blind pouch (canal of Gärtner) into which the catheter will almost invariably find its way. In both male and female, therefore, the passing of a catheter is an operation which demands special skill.
General symptoms of urinary disorders.—These are not so prominent in cattle as in horses, yet they are of a similar kind. There is a stiff or straddling gait with the hind legs and some difficulty in turning or in lying down and rising, the act causing a groan. The frequent passage of urine in driblets, its continuous escape in drops, the sudden arrest of the flow when in full stream, the rhythmic contraction of the muscles under the anus without any flow resulting, the swelling of the sheath, the collection of hard, gritty masses on the hair surrounding the orifice of the sheath, the occurrence of dropsies in the limbs under the chest or belly, or in either of these cavities, and finally the appearance of nervous stupor, may indicate serious disorder of the urinary organs. The condition of the urine passed may likewise lead to suspicion. It may be white, from crystallized carbonate of lime; brown, red, or even black, from the presence of blood or blood-coloring matter; yellow, from biliary coloring matter; frothy, from contained albumin; cloudy, from phosphates; glairy, from pus; it may also show gritty masses from gravel. In many cases of urinary disorder in the ox, however, the symptoms are by no means prominent, and unless special examination is made of the loins, the bladder, and the urine the true nature of the malady may be overlooked.
DIURESIS (POLYURIA, DIABETES INSIPIDUS, EXCESSIVE SECRETION OF URINE).
A secretion of urine in excess of the normal amount may be looked on as disease, even if the result does not lead to immediate loss of condition. Cattle fed on distillery swill are striking examples of such excess caused by the enormous consumption of a liquid feed, which nourishes and fattens in spite of the diuresis; the condition is unwholesome, and cattle that have passed four or five months in a swill stable have fatty livers and kidneys, and never again do well on ordinary feed. Diuresis may further occur from increase of blood pressure in the kidneys (diseases of the heart or lungs which hinder the onward passage of the blood, the eating of digitalis, English broom, the contraction of the blood vessels on the surface of the body in cold weather, etc.); also from acrid or diuretic plants taken with the feed (dandelion, burdock, colchicum, digitalis, savin, resinous shoots, etc.); from excess of sugar in the feed (beets, turnips, ripe sorghum); also from the use of frozen feed (frosted turnip tops and other vegetables), and from the growths of certain molds in fodder (musty hay, mow-burnt hay, moldy oats, moldy bread, etc.). Finally, alkaline waters and alkaline incrustations on the soil may be active causes. In some of these cases the result is beneficial rather than injurious, as when cattle affected with gravel in the kidneys are entirely freed from this condition by a run at grass, or by an exclusive diet of roots or swill. In other cases, however, the health and condition suffer, and even inflammation of the kidneys may occur.
Treatment.—The treatment is mainly in the change of diet to a more solid aliment destitute of the special, offensive ingredient. Boiled flaxseed is often the best diet or addition to the wholesome dry food, and, by way of medicine, doses of 2 drams each of sulphate of iron and iodid of potassium may be given twice daily. In obstinate cases 2 drams ergot of rye or of catechu may be added.