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,
Fuestenberg 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.
_Symptoms of urethral calculus._--The symptoms are violent straining to
urinate, but without any discharge, or with the escape of water in drops
only. Examination of the end of the penis will detect the swelling of
the papilla or the urethra behind it, and the presence of a hard mass in
the center. A probe inserted into the urethra will strike against the
gritty calculus. If the stone has been arrested higher up, its position
may be detected as a small, hard, sensitive knot on the line of the
urethra, in the median line of the lower surface of the penis, or on the
floor of pelvis in the median line from the neck of the bladder back to
the bend of the urethra beneath the anus. In any case the urethra
between the neck of the bladder and the point of obstruction is liable
to be filled with fluid, and to feel like a distended tube, fluctuating
on pressure.