Part 19

The carbonate of lime, which is present in large quantity in the urine of horses fed on green fodder, is practically insoluble, and therefore forms in the passages after secretion, and its microscopic rounded crystals give the urine of such horses a milky whiteness. It is this material which constitutes the soft, white, pultaceous mass that sometimes fills the bladder to repletion and requires to be washed out. In hay-fed horses carbonates are still abundant, while in those mainly grain-fed they are replaced by hippurates and phosphates--the products of the wear of tissues--the carbonates being the result of oxidation of the vegetable acids in the feed. Carbonate of lime, therefore, is a very common constituent of urinary calculi in herbivora, and in many cases is the most abundant constituent.

Oxalate of lime, like carbonate of lime, is derived from the burning up of the carbonaceous matter of the feed in the system, one important factor being the less perfect oxidation of the carbon. Indeed, Füstenberg and Schmidt have demonstrated on man, horse, ox, and rabbit that under the full play of the breathing (oxidizing) forces oxalic acid, like other organic acids, is resolved into carbonic acid. In keeping with this is the observation of Lehmann, that in all cases in which man suffered from interference with the breathing oxalate of lime appeared in the urine. An excess of oxalate of lime in the urine may, however, claim a different origin. Uric and hippuric acids are found in the urine of carnivora and herbivora, respectively, as the result of the healthy wear (disassimilation) of nitrogenous tissues. If these products are fully oxidized, however, they are thrown out in the form of the more soluble urea rather than as these acids. When uric acid out of the body is treated with peroxid of lead it is resolved into urea, allantoin, and oxalic acid, and Woehler and Frerrichs found that the administration of uric acid not only increased the excretion of urea but also of oxalic acid. It may therefore be inferred that oxalic acid is not produced from the carbonaceous feed alone but also from the disintegration of the nitrogenous tissues of the body. An important element of its production is, however, the imperfect performance of the breathing functions, and hence it is liable to result from diseases of the chest (heaves, chronic bronchitis, etc.). This is, above all, liable to prove the case if the subject is fed to excess on highly carbonaceous feeds (grass and green feed generally, potatoes, etc.).

Carbonate of magnesia, another almost constant ingredient of the urinary calculi of the horse, is formed the same way as the carbonate of lime--from the excess of carbonaceous feed (organic acids) becoming oxidized into carbon dioxid, which unites with the magnesia derived from the feed.

The phosphates of lime and magnesia are not abundant in urinary calculi of the horse, the phosphates being present to excess in the urine in only two conditions--(a) when the ration is excessive and especially rich in phosphorus (wheat, bran, beans, peas, vetches, rape cake, oil cake, cottonseed cake); and (b) when, through the morbid, destructive changes in the living tissues, and especially of the bones, a great quantity of phosphorus is given off as a waste product. Under these conditions, however, the phosphates may contribute to the formation of calculi, and this, above all, is liable if the urine is retained in the bladder until it has undergone decomposition and given off ammonia. The ammonia at once unites with the phosphate of magnesia to form a double salt--phosphate of ammonia and magnesia--which, being insoluble, is at once precipitated. The precipitation of this salt is, however, rare in the urine of the horse, though much more frequent in that of man and sheep.

These are the chief mineral constituents of the urine which form ingredients in the horse's calculi, for though iron and manganese are usually present it is only in minute quantities.

The excess of mineral matter in a specimen of urine unquestionably contributes to the formation of calculi, just as a solution of such matters out of the body is increasingly disposed to throw them down in the form of crystals as it becomes more concentrated and approaches nearer to the condition of saturation. Hence, in considering the causes of calculi we can not ignore the factor of an excessive ration, rich in mineral matters and in carbonaceous matters (the source of carbonates and much of the oxalates), nor can we overlook the concentration of the urine that comes from dry feed and privation of water, or from the existence of fever which causes suspension of the secretion of water. In these cases, at least the usual quantity of solids is thrown off by the kidneys, and as the water is diminished there is danger of its approaching the point of supersaturation, when the dissolved solids must necessarily be thrown down. Hence, calculi are more common in stable horses fed on dry grain and hay, in those denied a sufficiency of water or that have water supplied irregularly, in those subjected to profuse perspiration (as in summer), and in those suffering from a watery diarrhea. On the whole, calculi are most commonly found in winter, because the horses are then on dry feeding, but such dry feeding is even more conducive to them in summer when the condition is aggravated by the abundant loss of water by the skin.

In the same way the extreme hardness of the water in certain districts must be looked upon as contributing to the concentration of the urine and correspondingly to the production of stone. The carbonates, sulphates, etc., of lime and magnesia taken in the water must be again thrown out, and just in proportion as these add to the solids of the urine they dispose it to precipitate its least soluble constituents. Thus the horse is very subject to calculi on certain limestone soils, as over the calcareous formations of central and western New York, Pennsylvania, and Ohio, in America; of Norfolk, Suffolk, Derbyshire, Shropshire, and Gloucestershire, in England; of Poitou and Landes, in France; and Munich, in Bavaria.

The saturation of the urine from any or all of these conditions can only be looked on as an auxiliary cause, however, and not as in itself an efficient one, except on the rarest occasions. For a more direct and immediate cause we must look to the organic matter which forms a large proportion of all urinary calculi. This consists of mucus, albumen, pus, hyaline casts of the uriniferous tubes, epithelial cells, blood, etc., mainly agents that belong to the class of colloid or noncrystalline bodies. A horse may live for months and years with the urine habitually of a high density and having the mineral constituents in excess without the formation of stone or gravel; again, one with dilute urine of low specific gravity will have a calculus.

Rainey, Ord, and others furnish the explanation. They not only show that a colloid body, like mucus, albumen, pus, or blood, determined the precipitation or the crystalline salts in the solution, but they determined the precipitation in the form of globules, or spheres, capable of developing by further deposits into calculi. Heat intensifies this action of the colloids, and a colloid in a state of decomposition is specially active. The presence, therefore, of developing fungi and bacteria must be looked upon as active factors in causing calculi.

In looking, therefore, for the immediate causes of calculi we must consider especially all those conditions which determine the presence of albumen, blood, and excess of mucus, pus, etc., in the urine. Thus diseases of distant organs leading to albuminuria, diseases of the kidneys and urinary passages causing the escape of blood or the formation of mucus or pus, become direct causes of calculi. Foreign bodies of all kinds in the bladder or kidney have long been known as determining causes of calculi and as forming the central nucleus. This is now explained by the fact that these bodies are liable to carry bacteria into the passages and thus determine decomposition, and they are further liable to irritate the mucous membrane and become enveloped in a coating of mucus, pus, and perhaps blood.

The fact that horses, especially on the magnesian limestones, the same districts in which they suffer from goiter, appear to suffer from calculi may be similarly explained. The unknown poison which produces goiter presumably leads to such changes in the blood and urine as will furnish the colloid necessary for precipitation of the urinary salts in the form of calculi.

CLASSIFICATION OF URINARY CALCULI.

These have been named according to the place where they are found, renal (kidney), ureteric (ureter), vesical (bladder), urethral (urethra), and preputial (sheath, or prepuce). They have been otherwise named according to their most abundant chemical constituent, carbonate of lime, oxalate of lime, and phosphate of lime calculi. The stones formed of carbonates or phosphates are usually smooth on the surface, though they may be molded into the shape of the cavity in which they have been formed; thus those in the pelvis of the kidney may have two or three short branchlike prolongations, while those in the bladder are round, oval, or slightly flattened upon each other. Calculi containing oxalate of lime, on the other hand, have a rough, open, crystalline surface, which has gained for them the name of mulberry calculi, from a supposed resemblance to that fruit. These are usually covered with more or less mucus or blood, produced by the irritation of the mucous membrane by their rough surfaces. The color of calculi varies from white to yellow and deep brown, the shades depending mainly on the amount of the coloring matter of blood, bile, or urine which they may contain.

_Renal calculi._--These may consist of minute, almost microscopic, deposits in the uriniferous tubes in the substance of the kidney, but more commonly they are large masses and lodged in the pelvis. The larger calculi, sometimes weighing 12 to 24 ounces, are molded in the pelvis of the kidney into a cylindroid mass, with irregular rounded swellings at intervals. Some have a deep brown, rough, crystalline surface of oxalate of lime, while others have a smooth, pearly white aspect from carbonate of lime. A smaller calculus, which has been called coralline, is also cylindroid, with a number of brown, rough, crystalline oxalate of lime branches and whitish depressions of carbonate. These vary in size from 15 grains to nearly 2 ounces. Less frequently are found masses of very hard, brownish white, rounded, pealike calculi. These are smoother, but on the surface crystals of oxalate of lime may be detected with a lens. Some renal calculi are formed of more distinct layers, more loosely adherent to one another, and contain an excess of mucus, but no oxalate of lime. Finally, a loose aggregation of small masses, forming a very friable calculus, is found of all sizes within the limits of the pelvis of the kidney. These, too, are in the main carbonate of lime (84 to 88 per cent) and without oxalate.

Symptoms of renal calculi are violent, colicky, pains, appearing suddenly, very often in connection with exhausting work or the drawing of specially heavy loads, and in certain cases disappearing with equal suddenness. The nature of the colic becomes more manifest if it is associated with stiffness of the back and hind limbs, frequent passage of urine, and, above all, the passage of gravel with the urine, especially at the time of the access of relief. The passage of blood and pus in the urine is equally significant. If the irritation of the kidney goes on to active inflammation, then the symptoms of nephritis are added.

_Ureteric calculi._--These are so called because they are found in the passage leading from the kidney to the bladder. They are simply small, renal calculi which have escaped from the pelvis of the kidney and have become arrested in the ureter. They give rise to symptoms almost identical with those of renal calculi, with this difference, that the colicky pains, caused by the obstruction of the ureter by the impacted calculus, are more violent, and if the calculus passes on into the bladder the relief is instantaneous and complete. If the ureter is completely blocked for a length of time, the retained urine may give rise to destructive inflammation in the kidney, which may end in the entire absorption of that organ, leaving only a fibrous capsule containing an urinous fluid. If both the ureters are similarly blocked, the animal will die of uremic poisoning.

_Treatment of renal and ureteric calculi._--Treatment is unsatisfactory, as it is only the small calculi that can pass through the ureters and escape into the bladder. This may be favored by agents which will relax the walls of the ureters by counteracting their spasm and even lessening their tone, and by a liberal use of water and watery fluids to increase the urine and the pressure upon the calculus from behind. One or two ounces of laudanum, or 2 drams of extract of belladonna, may be given and repeated as it may be necessary, the relief of the pain being a fair criterion of the abating of the spasm. To the same end use warm fomentations across the loins, and these should be kept up persistently until relief is obtained. These act not only by soothing and relieving the spasm and inflammation, but they also favor the freer secretion of a more watery urine, and thus tend to carry off the smaller calculi. To accomplish this object further give cool water freely, and let the feed be only such as contains a large proportion of liquid, gruels, mashes, turnips, beets, apples, pumpkins, ensilage, succulent grasses, etc. If the acute stage has passed and the presence of the calculus is manifested only by the frequent passage of urine with gritty particles, by stiffness of the loins and hind limbs, and by tenderness to pressure, the most promising resort is a long run at pasture where the grasses are fresh and succulent. The long-continued secretion of a watery urine will sometimes cause the breaking down of a calculus, as the imbibition of the less dense fluid by the organic, spongelike framework of the calculus causes it to swell and thus lessens its cohesion. The same end is sought by the long-continued use of alkalies (carbonate of potassium), and of acids (muriatic), each acting in a different way to alter the density and cohesion of the stone. It is only exceptionally, however, that any one of these methods is entirely satisfactory. If inflammation of the kidneys develops, treat as advised under that head.

_Stone in the bladder (vesical calculus, or cystic calculus)._--These may be of any size up to over a pound in weight. One variety is rough and crystalline and has a yellowish-white or deep-brown color. These contain about 87 per cent carbonate of lime, the remainder being carbonate of magnesia, oxalate of lime, and organic matter. The phosphatic calculi are smooth, white and formed of thin, concentric layers of great hardness extending from the nucleus outward. Besides the phosphate of lime they contain the carbonates of lime and magnesia and organic matter. In some cases the bladder contains and may be even distended by a soft, pultaceous mass made up of minute, round granules of carbonates of lime and magnesia. This, when removed and dried, makes a firm, white, and stony mass. Sometimes this magma is condensed into a solid mass in the bladder by reason of the binding action of the mucus and other organic matter, and then forms a conglomerate stone of nearly uniform consistency and without stratification.

_Symptoms of stone in the bladder._--The symptoms of stone in the bladder are more obvious than those of renal calculus. The rough, mulberry calculi especially lead to irritation of the mucous membrane and frequent passing of urine in small quantities and often mingled with mucus or blood or containing minute, gritty particles. At times the flow is suddenly arrested, though the animal continues to strain and the bladder is not quite emptied. In the smooth, phosphatic variety the irritation is much less marked and may even be altogether absent. With the pultaceous deposit in the bladder there is incontinence of urine, which dribbles away continually and keeps the hair on the inner side of the thighs matted with soft magma. In all cases alike the calculus may be felt by the examination of the bladder with the oiled hand in the rectum. The pear-shaped outline of the bladder can be felt beneath, and within it the solid, oval body. It is most easily recognized if the organ is half full of liquid, as then it is not grasped by the contracting walls of the bladder, but may be made to move from place to place in the liquid. If a pultaceous mass is present it has a soft, doughy feeling, and when pressed an indentation is left.

In the mare the hard stone may be touched by the finger introduced through the short urethra.

_Treatment of stone in the bladder._--The treatment of stone in the bladder consists in the removal of the offending body; in the mare this is easily effected with the lithotomy forceps. These are slightly warmed and oiled, and carried forward along the floor of the passage of the vulva for 4 inches, when the orifice of the urethra will be felt exactly in the median line. Through this the forceps are gradually pushed with gentle, oscillating movement until they enter the bladder and strike against the hard surface of the stone. The stone is now grasped between the blades, care being taken to include no loose fold of the mucous membrane, and it is gradually withdrawn with the same careful, oscillating motions as before. Facility and safety in seizing the stone will be greatly favored by having the bladder half full of liquid, and if necessary one oiled hand may be introduced into the rectum or vagina to assist. The resulting irritation may be treated by an injection of laudanum, 1 ounce in a pint of tepid water.

The removal of the stone in the horse is a much more difficult proceeding. It consists in cutting into the urethra just beneath the anus and introducing the lithotomy forceps from this forward into the bladder, as in the mare. It is needful to distend the urethra with tepid water or to insert a sound or catheter to furnish a guide upon which the incision may be made, and in case of a large stone it may be needful to enlarge the passage by cutting in a direction upward and outward with a probe-pointed knife, the back of which is slid along in the groove of a director until it enters the bladder.

The horse may be operated upon in the standing position, being simply pressed against the wall by a pole passed from before backward along the other side of the body. The tepid water is injected into the end of the penis until it is felt to fluctuate under the pressure of the finger, in the median line over the bone just beneath the anus. The incision is then made into the center of the fluctuating canal, and from above downward. When a sound or catheter is used as a guide it is inserted through the penis until it can be felt through the skin at the point where the incision is to be made beneath the anus. The skin is then rendered tense by the thumb and fingers of the left hand pressing on the two sides of the sound, while the right hand, armed with a scalpel, cuts downward onto the catheter. This vertical incision into the canal should escape wounding any important blood vessel. It is in making the obliquely lateral incision in the subsequent dilatation of the urethra and neck of the bladder that such danger is to be apprehended.

If the stone is too large to be extracted through the urethra, it may be broken down with the lithotrite and extracted piecemeal with the forceps. The lithotrite is an instrument composed of a straight stem bent for an inch or more to one side at its free end so as to form an obtuse angle, and having on the same side a sliding bar moving in a groove in the stem and operated by a screw so that the stone may be seized between the two blades at its free extremity and crushed again and again into pieces small enough to extract. Extra care is required to avoid injury to the urethra in the extraction of the angular fragments, and the gravel or powder that can not be removed in this way must be washed out, as advised below.

When a pultaceous magma of carbonate of lime accumulates in the bladder it must be washed out by injecting water through a catheter by means of a force pump or a funnel, shaking it up with the hand introduced through the rectum and allowing the muddy liquid to flow out through the tube. This is to be repeated until the bladder is empty and the water come away, clear. A catheter with a double tube is sometimes used, the injection passing in through the one tube and escaping through the other. The advantage is more apparent than real, however, as the retention of the water until the magma has been shaken up and mixed with it hastens greatly its complete evacuation.

To prevent the formation of a new deposit any fault in feeding (dry grain and hay with privation of water, excess of beans, peas, wheat bran, etc.) and disorders of stomach, liver, and lungs must be corrected. Give abundance of soft drinking water, encouraging the animal to drink by a handful of salt daily. Let the feed be laxative, consisting largely of roots, apples, pumpkins, ensilage, and give daily in the drinking water a dram of either carbonate of potash or soda. Powdered gentian root (3 drams daily) will also serve to restore the tone of the stomach and system at large.

_Urethral calculus (stone in the urethra)._--This is less frequent in horses than in cattle and sheep, owing to the larger size of the urethra in the horse and the absence of the <b>S</b>-shaped curve and vermiform appendix. The calculi arrested in the urethra are never formed there, but consist of cystic calculi which have been small enough to pass through the neck of the bladder, but are too large to pass through the whole length of the urethra and escape. Such calculi therefore are primarily formed either in the bladder or kidney, and have the chemical composition of the other calculi found in those organs. They may be arrested at any point of the urethra, from the neck of the bladder back to the bend of the tube beneath the anus, and from that point down to the extremity of the penis. I have found them most frequently in the papilla on the extreme end of the penis, and immediately behind this.