A chronic cough may succeed the acute disease of the respiratory organs, such as pneumonia, bronchitis, laryngitis, etc. It accompanies chronic roaring, chronic bronchitis, broken wind; it may succeed influenza. As previously stated, cough is but a symptom and not a disease in itself.

Chronic cough is occasionally a.s.sociated with diseases other than those of the organs of respiration. It may be a symptom of chronic indigestion or of worms. In such cases it is caused by a reflex nervous irritation.

The proper treatment in all cases of chronic cough is to ascertain the nature of the disease of which it is a symptom, and then cure the disease if possible and the cough will cease.

The treatment of the affections will be found under their appropriate heads, to which the reader is referred.

PLEURODYNIA.

This is a form of rheumatism that affects the intercostal muscles; that is, the muscles between the ribs. The apparent symptoms are very similar to those of pleurisy. The animal is stiff and not inclined to turn round; the ribs are kept in a fixed state as much as possible. If the head is pulled round suddenly, or the affected side struck with the hand, or if the s.p.a.ces between the ribs are pressed with the fingers, the animal will flinch and perhaps emit a grunt or groan expressive of much pain. It is distinguished from pleurisy by the absence of fever, cough, the friction sound, the effusion into the chest, and by the existence of rheumatism in other parts. The treatment for this affection is the same as for rheumatism affecting other parts.

WOUNDS PENETRATING THE WALLS OF THE CHEST.

A wound penetrating the wall of the chest admits air into the thoracic cavity outside the lung. This condition is known as pneumothorax and may result in collapse of the lung. The wound may be so made that when the walls of the chest are dilating a little air is sucked in, but during the contraction of the wall the contained air presses against the torn part in such manner as entirely to close the wound; thus a small quant.i.ty of air gains access with each inspiration, while none is allowed to escape until the lung is pressed into a very small compa.s.s and forced into the anterior part of the chest. The same thing may occur from a broken rib inflicting a wound in the lung. In this form the air gains access from the lung, and there may not be even an opening in the walls of the chest. In such cases the air may be absorbed, when a spontaneous cure is the result, but when the symptoms are urgent it is recommended that the air be removed by a trocar and cannula or by an aspirator.

It is evident that the treatment of wounds that penetrate the thoracic cavity should be prompt. It should be quickly ascertained whether or not a foreign body remains in the wound; then it should be thoroughly cleaned with a solution of carbolic acid, 1 part in 40 parts of water.

The wound should then be closed immediately. If it is an incised wound, it should be closed with sutures or with adhesive plasters; if torn or lacerated, adhesive plaster may be used or a bandage around the chest over the dressing. At all events, air must be prevented from getting into the chest as soon and as effectually as possible. The after treatment of the wound should consist princ.i.p.ally in keeping the parts clean with a solution of carbolic acid, and applying fresh dressing as often as required to keep the wound in a healthy condition. Care should be taken that the discharges from the wound have an outlet in the most dependent part. (See Wounds and their treatment, p. 484.) If pleurisy supervenes, it should be treated as advised under that head.

THUMPS, OR SPASM OF THE DIAPHRAGM.

"Thumps" is generally thought by the inexperienced to be a palpitation of the heart. While it is true that palpitation of the heart is sometimes called "thumps," it must not be confounded with the affection under consideration.

In the beginning of this article on the diseases of the organs of respiration, the diaphragm was briefly referred to as the princ.i.p.al and essential muscle of respiration. Spasmodic or irregular contractions of it in man are manifested by what is familiarly known as hiccoughs.

Thumps in the horse is similar to hiccoughs in man although in all cases the peculiar noise is not made in the throat of the horse.

There should be no difficulty in distinguishing this affection from palpitation of the heart. The jerky motion affects the whole body, and is not confined to the region of the heart. If one hand is placed on the body at about the middle of the last rib, while the other hand is placed over the heart behind the left elbow, it will be easily demonstrated that there is no connection between the thumping or jerking of the diaphragm and the beating of the heart. In fact, when the animal is affected with spasms of the diaphragm the beating of the heart is usually much weaker and less perceptible than natural. Thumps is produced by causes similar to those that produce congestion of the lungs and dilatation or palpitation of the heart, and may occur in connection with these conditions. If not relieved, death usually results from congestion or edema of the lungs, as the breathing is interfered with by the inordinate action of this important muscle of inspiration so much that proper aeration of the blood can not take place. The treatment should be as prescribed for congestion of the lungs, and, in addition, antispasmodics, such as 1 ounce of sulphuric ether in warm water or 3 drams of asafetida.

RUPTURE OF THE DIAPHRAGM.

Post-mortem examinations after colic or severe accident sometimes reveal rupture of the diaphragm. This may take place after death, from the generation of gases in the decomposing carca.s.s, which distend the intestines so that the diaphragm is ruptured by the great pressure against it. The symptoms are intensely difficult respiration and great depression. There is no treatment.

DISEASES OF THE URINARY ORGANS.

BY JAMES LAW, F. R. C. V. S.,

_Formerly Professor of Veterinary Science, etc., in Cornell University._

USES OF THE URINARY ORGANS.

The urinary organs const.i.tute the main channel through which are excreted the nitrogenous or alb.u.minoid principles, whether derived directly from the feed or from the muscular and other nitrogenized tissues of the body. They const.i.tute, besides, the channel through which are thrown out most of the poisons, whether taken in by the mouth or skin or developed in connection with faulty or natural digestion, blood-forming, nutrition, or tissue destruction; or, finally, poisons that are developed within the body, as the result of normal cell life or of the life of bacterial or other germs that have entered the body from without. Bacteria themselves largely escape from the body through the kidneys. To a large extent, therefore, these organs are the sanitary scavengers and purifiers of the system, and when their functions are impaired or arrested the retained poisons quickly show their presence in resulting disorders of the skin and connective tissue beneath it, of the nervous system, or other organs. Nor is this influence one-sided.

Scarcely an important organ of the body can suffer derangement without entailing a corresponding disorder of the urinary system. Nothing can be more striking than the mutual balance maintained between the liquid secretions of the skin and kidneys during hot and cold weather. In summer, when so much liquid exhales through the skin as sweat, comparatively little urine is pa.s.sed, whereas in winter, when the skin is inactive, the urine is correspondingly increased. This vicarious action of skin and kidneys is usually kept within the limits of health, but at times the draining off of the water by the skin leaves too little to keep the solids of the urine safely in solution, and these are liable to crystallize out and form stone and gravel. Similarly the pa.s.sage, in the sweat, of some of the solids that normally leave the body, dissolved in the urine, serves to irritate the skin and produce troublesome eruptions.

PROMINENT CAUSES OF URINARY DISORDERS.

A disordered liver contributes to the production under different circ.u.mstances of an excess of biliary coloring matter which stains the urine; of an excess of hippuric acid and allied products which, being less soluble than urea (the normal product of tissue change), favor the formation of stone, of taurocholic acid, and other bodies that tend when in excess to destroy the blood globules and to cause irritation of the kidneys by the resulting hemoglobin excreted in the urine, and of glycogen too abundant to be burned up in the system, which induces saccharine urine (diabetes). Any disorder leading to impaired functional activity of the lungs is causative of an excess of hippuric acid and allied bodies, of oxalic acid, of sugar, etc., in the urine, which irritate the kidneys, even if they do not produce solid deposits in the urinary pa.s.sages. Diseases of the nervous system, and notably of the base of the brain and of the spinal cord, induce various urinary disorders, prominent among which are diabetes, chylous urine, and alb.u.minuria. Certain affections, with imperfect nutrition or destructive waste of the bony tissues, tend to charge the urine with phosphates of lime and magnesia and endanger the formation of stone and gravel. In all extensive inflammations and acute fevers the liquids of the urine are diminished, while the solids (waste products), which should form the urinary secretion, are increased, and the surcharged urine proves irritant to the urinary organs or the retained waste products poison the system at large.

Diseases of the heart and lungs, by interfering with the free, onward flow of the blood from the right side of the heart, tend to throw that liquid back on the veins, and this backward pressure of venous blood strongly tends to disorders of the kidneys. Certain poisons taken with the feed and water, notably that found in magnesian limestone and those found in irritant, diuretic plants, are especially injurious to the kidneys, as are also various cryptogams, whether in musty hay or oats.

The kidneys may be irritated by feeding green vegetables covered with h.o.a.r frost or by furnishing an excess of feed rich in phosphates (wheat bran, beans, peas, vetches, lentils, rape cake, cottonseed cake) or by a privation of water, which entails a concentrated condition and high density of the urine. Exposure in cold rain or snow storms, cold drafts of air, and damp beds are liable to further disorder an already overworked or irritable kidney. Finally, sprains of the back and loins may cause bleeding from the kidneys or inflammation.

The right kidney, weighing 23-1/2 ounces, is shaped like a French bean, and extends from the loins forward to beneath the heads of the last two ribs. The left kidney (Pl. VIII) resembles a heart of cards, and extends from the loins forward beneath the head of the last rib only. Each consists of three distinct parts--(a) the external (cortical), or vascular part, in which the blood vessels form elaborate capillary networks within the dilated globular sacs which form the beginnings of the secreting (uriniferous) tubes and on the surface of the sinuous, secreting tubes leading from the sacs inward toward the second, or medullary, part of the organ; (b) the internal (medullary) part, made up in the main of blood vessels, lymphatics, and nerves extending between the notch on the inner border of the kidney to and from the outer vascular portion, in which the secretion of urine is almost exclusively carried on; and (d) a large, saccular reservoir in the center of the kidney, into which all uriniferous tubes pour their secretions and from which the urine is carried away through a tube g (ureter), which pa.s.ses out of the notch at the inner border of the kidney and which opens by a valve-closed orifice into the roof of the bladder just in front of its neck. The bladder is a dilatable reservoir for the retention of the urine until the discomfort of its presence causes its voluntary discharge. It is kept closed by circular, muscular fibers surrounding its neck or orifice, and is emptied by looped, muscular fibers extending in all directions forward from the neck around the blind anterior end of the sac. From the bladder the urine escapes through a dilatable tube (urethra) which extends from the neck of the bladder backward on the floor of the pelvis, and in the male through the p.e.n.i.s to its free end, where it opens through a pink, conical papilla.

In the mare the urethra is not more than an inch in length, and is surrounded by the circular, muscular fibers closing the neck of the bladder. Its opening may be found directly in the median line of the floor of the v.u.l.v.a, about 4-1/2 inches from its external opening.

GENERAL SYMPTOMS OF DISEASE.

These apply especially to acute inflammations and the irritation caused by stone. The animal moves stiffly on the hind limbs, straddles, and makes frequent attempts to pa.s.s urine, which may be in excess, deficient in amount, liable to sudden arrest in spite of the straining, pa.s.sed in driblets, or entirely suppressed. Again, it may be modified in density or const.i.tuents. Difficulty in making a sharp turn, or in lying down and rising with or without groaning, dropping the back when mounted or when pinched on the loins is suggestive of kidney disease, and so to a less extent are swelled legs, dropsy, and diseases of the skin and nervous system. The oiled hand introduced through the r.e.c.t.u.m may feel the bladder beneath and detect any overdistention, swelling, tenderness, or stone. In ponies the kidneys even may be reached.

EXAMINATION OF THE URINE.

In some cases the changes in the urine are the sole sign of disease. In health the horse's urine is of a deep amber color and has a strong odor.

On a feed of grain and hay it may show a uniform transparency, while on a green ration there in an abundant white deposit of carbonate of lime.

Of its morbid changes the following are to be looked for: (1) _Color_: White from deposited salts of lime; brown or red from blood clots or coloring matter; yellow or orange from bile or blood pigment; pale from excess of water; or variously colored from vegetable ingredients (santonin makes it red; rhubarb or senna, brown; tar or carbolic acid, green). (2) _Density_: The horse's urine may be 1.030 or 1.050, but it may greatly exceed this in diabetes and may sink to 1.007 in diuresis.

(3) _Chemical reaction_, as ascertained by blue litmus or red test papers. The horse on vegetable diet has alkaline urine turning red test papers blue, while in the sucking colt and the horse fed on flesh or on his own tissue (in starvation or abstinence during disease) it is acid, turning blue litmus red. (4) _Organic const.i.tuents_, as when glairy from alb.u.men coagulable by strong nitric acid and boiling, when charged with microscopic casts of the uriniferous tubes, with the eggs or bodies of worms, with sugar, blood, or bile. (5) _In its salts_, which may crystallize out spontaneously, or on boiling, or on the addition of chemical reagents.

[Ill.u.s.tration: PLATE VIII.

LONGITUDINAL SECTION THROUGH KIDNEY.]

[Ill.u.s.tration: PLATE IX.

MICROSCOPIC ANATOMY OF KIDNEY.]

[Ill.u.s.tration: PLATE X.

MICROSCOPIC ANATOMY OF KIDNEY.]

Alb.u.minous urine in the horse is usually glairy, so that it may be drawn out in threads, but its presence can always be tested as follows: If the liquid is opaque, it may be first pa.s.sed through filter paper; if very dense and already precipitating its salts, it may be diluted with distilled water; add to the suspected liquid acetic acid drop by drop until it reddens the blue litmus paper; then boil gently in a test tube; if a precipitate is thrown down, set the tube aside to cool and then add strong nitric acid. If the precipitate is not dissolved, it is alb.u.men; if dissolved it is probably urate or hippurate of ammonia. Alb.u.men is normally present in advanced gestation; abnormally it is seen in diseases in which there occurs destruction of blood globules (anthrax, low fevers, watery states of the blood, dropsies), in diseases of the heart and liver which prevent the free escape of blood from the veins and throw back venous pressure on the kidneys, in inflammation of the lungs and pleurae, and even tympany (bloating), doubtless from the same cause, and in all congestive or inflammatory diseases of the kidneys, acute or chronic.

Casts of the uriniferous tubes can be seen only by placing the suspected urine under the microscope. They are usually very elastic and mobile, waving about in the liquid when the cover gla.s.s is touched, and showing a uniform, clear transparency (waxy) or entangled circular epithelial cells or opaque granules or flattened, red-blood globules or clear, refrangent oil globules. They may be even densely opaque from crystals of earthy salts.

Pus cells may be found in the urine a.s.sociated with alb.u.men, and are recognized by clearing up, when treated with acetic acid, so that each cell shows two or three nuclei.

DIURESIS (POLYURIA, DIABETES INSIPIDUS, OR EXCESSIVE SECRETION OF URINE).

This consists in an excessive secretion of a clear, watery urine of a low specific gravity (1.007) with a correspondingly ardent thirst, a rapidly advancing emaciation, and great loss of strength and spirit.

_Causes._--Its causes may be any agent--medicinal, alimentary, or poisonous--which unduly stimulates the kidneys; the reckless administration of diuretics, which form such a common const.i.tuent of quack horse powders; acrid diuretic plants in gra.s.s or hay; new oats still imperfectly cured; an excess of roots or other very watery feed; a full allowance of salt to animals that have become inordinately fond of it; but, above all, feeding on hay, grain, or bran which has not been properly dried and has become musty and permeated by fungi. Thus hay, straw, or oats obtained in wet seasons and heating in the rick or stack is especially injurious. Hence this malady, like coma somnolentum (sleepy staggers), is widespread in wet seasons, and especially in rainy districts.

_Symptoms._--The horse drinks deep at every opportunity and pa.s.ses urine on every occasion when stopped, the discharge being pale, watery, of a low density, and inodorous; in short, it contains a great excess of water and a deficiency of the solid excretions. So great is the quant.i.ty pa.s.sed, however, that the small amount of solids in any given specimen amounts in 24 hours to far more than the normal--a fact in keeping with the rapid wasting of the tissues and extreme emaciation. The flanks become tucked up, the fat disappears, the bones and muscles stand out prominently, the skin becomes tense and hidebound, and the hair erect, scurfy, and deficient in l.u.s.ter. The eye becomes dull and sunken, the spirits are depressed, the animal is weak and sluggish, sweats on the slightest exertion, and can endure little. The subject may survive for months, or may die early of exhaustion. In the slighter cases, or when the cause ceases to operate, a somewhat tardy recovery may be made.