Chapter XIV: Part 14

When extreme dilatation exists with the hypertrophy, sedatives should be given cautiously and their effects carefully watched as the heart is often dangerously susceptible to depressing influences. When the disease has advanced so far as to cause abundant dropsical effusions it is futile to resort to treatment as amelioration can rarely be looked for, not even to the extent of allowing an animal to be fattened.

The value of arsenic in most cases of broken wind (heaves) has suggested the inquiry whether it does not operate directly on the heart. Leblanc who advances this query might have quoted in explanation the known power of arsenic to retard and arrest tissue change, with its natural consequences, the diminished amount of effete matter thrown into the blood in any given time, and the lessened necessity for an active circulation to supply any great waste of structure. It may benefit such cases in this way but does so probably to a far greater extent by an influence on the nervous function analogous to its action in neuralgia and other purely nervous disorders. Dilatation of the heart which usually exists in _heaves_ is usually benefited by tonics which like arsenic are destitute of stimulating properties.

ATROPHY.

Simple, eccentric, concentric. Usually eccentric. Causes, effusion in
pericardium, obstruction of coronary arteries, by false membranes,
etc., general inanition. Symptoms, beats weak, sounds loud, clear,
decreased area of dulness on percussion, pulse slow, weak, under
excitement unequal, irregular, intermittent with palpitation, dropsy
of limbs, etc., murmur with 1st sound. Treatment only in early stages
by removal of the cause.

The loss of substance in the muscular walls of the heart is either _simple_ when there is no change in the capacity of its different cavities:—=eccentric= when the chambers of the heart are enlarged; or =concentric= when these chambers are reduced in size. Like hypertrophy it may affect the walls of one chamber to the exclusion of the others.

Atrophy is much less frequent in the lower animals than hypertrophy and in nearly all cases on record it was associated with dilatation.

The _causes_ are not always very evident. Effusion into the pericardium is one of the most frequent, the compression of the heart impairing its nutrition and decreasing its size. Especially is it hurtful when several layers of false membranes deposited on the surface of the heart become organized, preventing its sufficient dilatation and compressing its nutrient bloodvessels. A case of this kind in a dog occurred to Leblanc; the right auriculo-ventricular opening was surrounded by thick organized layers of false membranes which by their contraction had largely diminished the opening and even pressed on the coronary artery cutting off to a great extent the supply of blood to the walls of the ventricle. Another alleged cause is a prolonged insufficient nourishment to the entire body. Leblanc has also observed this in dogs the subjects of long continued wasting maladies.

_Symptoms._ In pure atrophy these are the opposite of those seen in hypertrophy. The beats of the heart are weak or inappreciable to the hand placed on the side of the chest behind the left elbow. The sounds of the heart are loud and clear, their intensity being proportionate to the thinning of the walls and the dilatation of the chambers. Percussion so far as it can be made effectual, which is chiefly in dogs, shows a diminished area of dulness. The pulse is slow, weak, or indistinct, compressible, becoming accelerated, unequal, irregular, and intermittent when the patient is excited. Palpitation is frequent, breathing is difficult or easily embarrassed and there is a tendency to dropsy of the limbs and dependent parts. These symptoms are usually associated with considerable prostration and depression.

These are often complicated by symptoms of valvular disease or dilatation.

Atrophy progresses slowly and rarely causes death in the earlier stages. In its advanced stages when dropsy has supervened little can be done even in its mitigation. In the earliest stages only can good be done by employing measures calculated to remove its causes and thus put a stop to its progress.

DILATATION OF THE HEART.

Result of obstruction to circulation. In right ventricle usually. In
auricle from narrow auriculo-ventricular opening. Pure dilatation from
sudden extreme blood pressure as in inflammations of the lungs. In fat
cattle from fatty obstructions around the heart and great vessels.
Weakness of cardiac muscles in fatty degeneration, fevers, debility,
etc. Symptoms, dyspnœa under slight exertion, unsteady walk, cold,
dropsical limbs, venous pulse, pulse small, weak, irregular,
intermittent, with palpitations. Treatment, in early stages arrest the
causes, arsenic, digitalis, fatten for butcher.

Dilatation of the right cavities of the heart is one of the most common heart diseases of the horse. It is an almost constant condition in advanced broken wind, and is a frequent concomitant of hypertrophy and an occasional one of atrophy of the heart. Its usual direct cause is some obstacle to the free escape of blood from the cavity affected. Thus in broken wind the difficulty of the circulation through the lungs causes accumulation in the pulmonary artery and right ventricle of the heart, the walls of which are distended because of the unwonted internal pressure. When the dilatation of this ventricle reaches a certain stage the auriculo-ventricular opening is equally widened, the valves become insufficient to close it and the right auricle and venæ cavæ participate in turn in the internal pressure and dilatation. The right ventricle is more often affected than the left, because of the greater frequency of obstruction in the circulation through the lungs than in that through the general system, and because of the thinness of its walls which more readily give way under internal pressure. Dilatation may result from disease of the great arteries, from diminution of their calibre by the pressure of tumours, or by narrowing of their openings at the heart, whether as the result of diseased valves or other morbid condition. As affecting the auricles primarily its usual cause is narrowing of the auriculo-ventricular opening from some abnormal deposit. The extreme thinness of the walls of the auricles allows these to give way under internal pressure even much more readily than the right ventricle.

The causes it will be seen are similar to those inducing hypertrophy, and hence the frequent coexistence of the two. Pure dilatation occurs especially when internal pressure takes place suddenly and to excess, and while the nutritive functions are to a great extent in abeyance. Such conditions are found in acute inflammations of the respiratory organs, or of the inner or outer membranes of the heart, and the rapid deposit in the lungs of tubercles or other abnormal material.

Dilatation of the right side of the heart is a common complaint in overfed cattle, and is apparently due to the diminished power of resistance in the walls of the heart, the muscular substance of which is partly replaced by fatty granules, and to the obstruction offered to the circulation by the extraordinary accumulation of fat around the base of the heart and the commencement of the large blood vessels. Though a diseased condition this rarely shortens life or interferes with the uses to which cattle are put.

The heart walls are similarly weakened and yield more readily to the internal blood pressure in endocarditis, myocarditis, pericarditis, high fever, infectious diseases, poisonings, anæmia, and debilitating diseases generally. Debility and incapacity to resist the blood pressure is the essential prerequisite to dilatation.

The _symptoms_ which have been already enumerated in the table given under the head of _hypertrophy_ are mainly these: Loss of appetite, spirit and endurance; faintness and difficulty of breathing on the slightest exertion; habitual coldness with a tendency to dropsy of the extremities; loss of control over the extremities when walked or trotted far; venous pulsation in the jugulars; heart’s impulse weak and undulatory or tremulous, or under exertion tumultuous or palpitating; murmur often present with the first sound; the first or more commonly the second sound may be doubled; pulse small, weak, irregular, and often intermittent, and frequently livid spots in the nasal mucous membrane. Paroxysms of unsteady gait from irregular circulation in the brain is frequent, and Dyer asserts that he has repeatedly seen blindness as a result of this condition.

In _treatment_ the main purpose should be to put a stop to the cause of the disease before it has been developed to a dangerous extent. When the malady is manifested by the symptoms above enumerated the subject is rendered permanently unfit for service and will probably die suddenly under some slight exertion. Fattening animals in a condition of quietude will often lay on flesh for an indefinite length of time notwithstanding that the heart is considerably dilated. (See note on digitalis, strophanthus and arsenious acid in dilated heart, under the head of _hypertrophy_). To relieve the asthmatic attacks attending on an overtaxed heart Zuill strongly recommends the combination of iodide of potassium, digitalis, nux vomica and coca. But heart tonics are often much more affective after the bowels and portal system have been unloaded by a laxative.

INFLAMMATIONS IN THE HEART.

These are among the most common diseases of this organ and moreover lead to many of the changes in structure to be hereafter noticed so that it is convenient to treat of them here. According to their relative frequency they may be ranged:—1st. Inflammation of the external covering of the heart—pericarditis; 2d. Inflammation of the internal lining membrane of the heart—endocarditis; and 3d. Inflammation of the muscular substance of the heart—carditis.

PERICARDITIS.

Definition. Frequency in different genera. Causes, rheumatic,
traumatism, extension from pleurisy. Unwholesome buildings and
localities, debility. Symptoms, chill, reaction, pleuritic symptoms,
hyperthermia, tenderness behind left elbow only, friction sound
synchronous with heart beat, later it is lost and heart sounds are
muffled, increased area of dulness on percussion, oppressed breathing,
venous pulse, patient statant, little fever in chronic cases.
Traumatism from the stomach, digestive disorder, grunting, dropsy
under the sternum with little fever at first. Lesions, as in pleurisy,
obliteration of pericardial sac. In traumatism from stomach the
foreign body is formed in the cardiac end of a band of lymph extending
to the reticulum. Treatment, in chill, after reaction, medicinal
measures as in pleurisy, local applications to the region of the
heart. Paracentesis, insertion of needle, antiseptic precautions.
Chronic pericarditis in oxen.

_Definition._ Inflammation of the strong fibro-serous sac in which the heart is contained and which is reflected on the muscular substance of that organ so as to form its external covering.

This is the most common inflammatory disease of the heart and has been met with more frequently in horses and cattle than in the smaller quadrupeds.

_Causes._ It frequently coincides with or follows other diseases such as _influenza_, _pleuro-pneumonia_ and above all _rheumatism_. In cattle and goats wounds from sharp pointed bodies, (needles, pins, nails, etc.), which have been swallowed with the food and have passed through the walls of the second stomach, the diaphragm and pleura to the heart constitute a frequent cause in cattle. The pericardium has been punctured by a fractured rib and has been implicated in inflammation attendant on an abscess or other lesion in the walls of the chest. Besides these the general influences which cause uncomplicated attacks of the disease are the same as those producing pleurisy, peritonitis, rheumatism and inflammation of serous membranes generally. These are sudden changes from heat to cold, cold winds, cold draughts, drenching, chilling rains in animals already overheated and exhausted, or prolonged exposure in severe weather, in low states of the system. Leblanc justly remarks that “with the morbid influences which appear specific, there often coincide intemperate seasons, badly arranged buildings, a want of sufficient attention to the conditions of health, and in the case of herbivora, wet, cold, and badly exposed pastures.” In other words whatever deteriorates the health and vitality predisposes.

_Symptoms._ These are less characteristic than in man owing to the smaller portion of the heart exposed, but they are usually marked enough to permit a recognition of the disease. _Acute form._ The affection is ushered in by chill, general fever, hyperthermia, (103° to 104°), staring coat, hot, dry mouth, dilated nostrils, excited, difficult breathing, double lifting of the flank with each expiration, the existence of a prominent ridge from the lower end of the last ribs along the flank to the outer angle of the hip bone, as in pleurisy, pinched, anxious expression of countenance, fixed eyes, accelerated, full, hard and often wiry pulse, and tenderness when the ribs behind the left elbow are pinched or struck. The same tenderness is noticed particularly in the ox and smaller quadrupeds when pressure or compression is made beneath the breast bone. Auscultation over the lower ends of the fifth and sixth ribs and their cartilages detects a friction or rubbing sound in the early stages and until liquid has been thrown out into the pericardial sac. This sound may be at first the finest possible creaking, afterward increasing to a distinct rubbing, is synchronous with the beat of the heart, and usually with the first sound. It is distinguished from the friction sound of pleurisy in occurring rythmically with the sounds of the heart and not with those of breathing, and from sounds produced in the interior of the heart by its absence when auscultation is made over the carotid or other large artery. This friction sound is lost when serous effusion takes place into the pericardium, but reappears when the liquid is absorbed in the process of recovery. Until effusion takes place the impulse of the heart is strong, often irregular, in force, and sometimes accompanied by a purring tremor or, according to Leblanc, a metallic tinkle.

When effusion has taken place the pulse is weaker and softer, irregular or intermittent, the impulse of the heart is weaker, the friction sound is lost, and the area of dulness corresponding to the heart is increased. Percussion shows it to extend higher than three inches above the breast bone in the horse and more than two or two and a half inches transversely. It is distinguished from the effusion of pleurisy in this, that the dulness is confined to the anterior part of the chest, having the outline of an inverted cone, and does not extend backward along a horizontal line, and, in solipedes, in not showing equally on both sides. In the smaller animals it may be distinguished by not always occupying the dependent part of the chest when the animal is placed in different positions. As the effusion increases, the heart’s sounds, previously strong, become first muffled, then more and more distant until they may become altogether imperceptible. The difficulty and oppression of the breathing increases, the nose is protruded, the eyes more rigidly fixed, and the face more haggard; a venous pulse, apparently due to the compression of the heart and large veins by the fluid, is seen in the lower ends of the jugulars, and the animal obstinately stands as indeed the solipeds do all through the disease. At this advanced stage dropsies of the limbs, sheath, and other dependent parts of the body are frequent.

A painful cough is sometimes though by no means invariably present throughout the disease. Emaciation takes place rapidly and in the more acute cases death ensues in five to eight days. A fatal issue may be delayed until after three weeks or the affection may merge into a _chronic form_.

=Chronic Pericarditis= is sometimes seen in the ox without any preceding acute attack. This is manifested by the local symptoms without the accompanying acute fever. Along with a _slight_ fever, there is the oppressed breathing aggravated by exertion, the weak irregular or intermittent pulse, the weak or distant heart sounds, the absence of respiratory sounds and the dullness on percussion over a space represented by an inverted cone at the anterior part of the chest on each side, the venous pulse in the neck and the general tendency to dropsy.

If the _pericarditis_ has been the result of sharp pointed metallic bodies swallowed and afterwards making their way to the heart, it is sometimes preceded by eructations, tympany, difficulty in swallowing or in rumination, and by dropsy under the sternum, but more frequently the heart symptoms are the first to be noticed. It is not attended by the high fever of other pericarditis.

_Post Mortem Appearances._ These do not differ materially from those of pleurisy, to which accordingly the reader is referred. The effusions and false membranes are of course localized in the sac of the pericardium. A frequent termination is a permanent adhesion of the pericardium throughout more or less of its extent to the surface of the heart. In cases of death the serous effusion is commonly colored with blood though mostly from a _post mortem_ infiltration of blood from the congested lungs. The effusion has been known to measure fifteen litres in the horse. It may be purulent or combined with fœtid gases, particularly in traumatic cases. After mild attacks white patches (milk spots) are often left extending, it may be only through the pericardium and in other cases reaching into the muscular substance. At a less advanced stage the false membranes are yellow, with a rough or villous surface, they may be softened from fatty degeneration or they may be more or less completely calcified.

When the cause has been perforation by a metallic body, it will be found surrounded by exudate enveloping a canal or band extending to the diaphragm or stomach.

_Treatment._ Pericarditis often proves fatal but it is by no means invariably so in uncomplicated cases. There is especial danger when serous effusion is excessive, when it occurs in a weak and debilitated subject, or when it is complicated by pleurisy, influenza or rheumatism. The preliminary chill may be met by the measures advised for the rigor of pleurisy, but if the malady is developed other treatment is required. The medication is still essentially as for pleurisy, only the primary disease (rheumatism, influenza, pneumonia) must be specially attended to when such is present. Acute pain may be met by carefully graduated doses of opium or aconite and by the moist jacket or fomentations. Some employ icebags to soothe at once inflammation and pain and in the absence of rheumatism these may be resorted to. In the small animals leeches may be applied over the cardiac region. Dry cupping is a good alternative applicable to all.

An active purgative is demanded unless the affection is attended by a low type of fever or has occurred during the course of an epizootic disease (Horse 5 to 7 drachms aloes, cow 1 to 2 lbs. Epsom Salts, dog 1 oz. castor oil). After the walls of the chest have been well fomented they may be enveloped in a large mustard poultice which must be continued until a considerable effusion has taken place beneath the skin. To moderate and control the heart’s action give digitalis (horse and ox ½ drachm, dog 2 to 4 grains) four times a day. After the purgative has acted an ounce of nitrate or acetate of potass may be given daily to the larger quadrupeds (1½ drachms to sheep and pigs, and 20 grains to dogs) in the drinking water. These agents together with the digitalis must be pushed to the largest doses when the effusion has taken place abundantly and when it threatens to dangerously interfere with the heart’s action. Pilocarpin is a dernier resort, to be used with caution. In similar circumstances, ointment or tincture of iodine should be freely applied over the chest in the region of the heart. Mustard and other vesicants repeatedly applied often greatly hasten the reabsorption of the liquids.

From the first the animal must be warmly clothed and every means employed to obtain free circulation and warmth on the surface. The legs must be well rubbed and wound in warm flannel bandages, or this failing, may have mustard freely applied to them. Warm injections must be at the same time thrown into the rectum and will benefit by soliciting the action of the bowels as well as in raising the temperature of the surface generally. The food allowed should be warm mashes of wheat bran, boiled linseed and similar agents in small quantities.

If the amount of effusion threatens a fatal result, it may be drawn off by a cannula and trochar introduced between the cartilages of the fifth and sixth ribs, by a valvular wound and with antiseptic precaution (see hydrothorax), care being taken to avoid puncturing the heart itself.

The trochar or aspirator needle should be pushed in a direction upward and inward until resistance ceases or it is felt that the heart has been touched. A caoutchouc tube may now be attached to it and allowed to depend twelve or eighteen inches, and its lower end should be plunged in a weak solution of boric acid or other antiseptic. This avoids the entrance of air and insures against the introduction of ærial bacteria.

When the vital powers are being exhausted stimulants must be given to support the animal, combined with iodide of potassium. (See advice concerning the allied condition in _Hydrothorax_).

In the _chronic pericarditis of oxen_ the fatality is greater. Treatment consists mainly in counterirritants and powerful diuretics employed in doses determined by the strength of the animal, and combined with stimulants and tonics as in the advanced stages of the acute disease.

In complicated forms of pericarditis attention must be given mainly to the constitutional affection, thus in _influenza_ a stimulating and supporting treatment is demanded, and in _rheumatism_ colchicum, acetate of potass, salicylate of soda, salol and similar agents must be freely administered, though not to the exclusion of counterirritants to the region of the heart, and other measures demanded by the heart diseases.

ENDOCARDITIS.

Definition. Pathology and lesions, congestion of the endocardium
covering the valves, valves liable through friction and strain,
exudation in or on the serosa rendering it opaque, coagula of fibrine
on the surface, secondary endocarditis mycotic, microbes, changes in
serosa, distortions and degenerations of valves. Symptoms, as in
pericarditis, with violent heart impulse of varying force, clear
metallic sound, blowing murmurs, weak pulse decreasing in force,
irregular, intermittent, absence of local tenderness, no friction
sound, no increase in area of dulness, if lesions are in right
heart—venous pulse, venous congestion, dropsies. Valve lesions, in
mitral valve—general heart symptoms and murmur with 1st heart sound,
2d sound may be repeated and exceptionally a venous pulse—in tricuspid
valve—same with constant venous pulse, venous congestion and dropsy;
narrowing of the mitral orifice—general heart symptoms and blowing
murmur before the 1st sound; narrowing of the tricuspid orifice—same
with murmur sometimes audible on the right side; insufficiency of
aortic valves—general heart symptoms and murmur with 2d heart sound,
double rushing sound in arteries and delay of pulse beat at jaw;
lesions in pulmonary valves—same but without double rush in arteries,
or delay of pulse beat at jaw. Loose coagula. Embolism. Causes, as in
pericarditis and strain on valves, and poisons and microbes in the
blood. Prognosis grave. Treatment, as in the early stages of
pericarditis, antirheumatics and germicides more, and diuretics less
desirable. For clots iodides, alkalies.

_Definition._ Inflammation of the serous membrane lining the chambers and covering the valves of the heart.

_Pathology and Morbid Anatomy._ The causes and symptoms will be better understood after the diseased conditions have been comprehended. The earliest changes are the reddening and thickening of the lining membrane of the heart but above all of that covering the valves. The valves are particularly exposed to inflammation by reason of the friction of the blood when violently forced through the narrow opening in excited conditions of the heart, by the strain thrown upon them from the violent contractions of the heart or the recoil of blood in the arteries, and by their susceptibility in common with all other fibrous structures to rheumatic inflammation. The redness is of the ramified or branching kind characteristic of inflammation, and is neither removable by washing the surface nor does it correspond in position with the colored portion only of a clot which the cavity in question may contain, as seen in bloodstaining occurring after death.

There is further exudation of plastic lymph into and beneath the serous membrane, rendering it opaque, white and thick, or on its surface forming granular elevations, and in the case of the valves becoming moulded into ridges or festoons by the mutual pressure of the different flaps on each other. The inflamed surfaces are further liable to be covered by masses of blood clot in successive layers, deposited by the action of the fibrinogenous matter developed in the inflamed part. These clots sometimes accumulate in considerable masses, firmly adherent to the heart’s walls or valves by their attached surface, but soft and filamentous on their free aspect. These clots or polypi, as they have been called, are soft and loose on their free surface, and become firmer toward their points of attachment. In other words their consistency is in direct ratio to their age. If of old standing they are usually pale yellow or white and streaked with red, while if recent they are mostly red throughout. They vary in size from a thin film to a mass filling up nearly the entire cavity in which they are lodged, and as they frequently extend through the auriculo-ventricular openings or become applied against this or the opening of the great artery, they seriously and sometimes fatally interfere with the circulation. Leblanc asserts that large masses of this kind may be deposited in a few days or even hours, causing sudden deaths, and especially in dogs. He has found other circumstances than endocarditis to cause these fibrinous deposits, and especially the absorption of pus, or the sudden suppression of a long standing discharge, as in catarrh of the air passages. If death does not immediately ensue, these fibrinous deposits may become vascular, as is the case with false membranes in the pleuræ, becoming organized into fibrous tissue, or even degenerating into calcareous matter, necrotic debris, or pus, several instances of which as occurring in horse and cow are on record.

These cases illustrate _endocarditis by infection_ (_mycotic_, _malignant_, _or ulcerative endocarditis_), which occurs independently, or as an extension of a bacteridian disease, primarily localized elsewhere in the system. Thus it is a secondary lesion in infectious omphalitis, pneumonia, pleurisy, arthritis, abscess, pyæmia, etc. Beside the general lesions of endocarditis and a great tendency to molecular death of the new formations and the underlying tissues, there is the presence of specific germs which have been the occasion of the disease. Among these the staphylococcus pyogenes aureus, the streptococcus pyogenes, and the diplococcus pneumoniæ, have been particularly noted. In case the valves were already diseased, they become especially liable to be colonized by any such bacteria that may be circulating in the blood.

In the early stage there may be a mere swelling of the valves, with as yet a smooth, unbroken surface, but with enlargement and increase of the connective tissue cells, later fungous vegetations start out from the surface, and on these the fibrine of the blood is deposited in layers.

Besides the formation of clots on their surfaces other changes occur on the cardiac valves as the result of inflammation. The organization of the exuded lymph within and upon them leads to rigidity, loss of elasticity, unevenness of their surface, contraction and puckering so that they can no longer approximate to each other, but leave the orifice imperfectly closed. They may, moreover, have gristle or bone deposited in their substance. The osseous degeneration of such new products appears to be the most common cause of those ossifications of the heart, of which specimens are to be found in nearly all veterinary museums.

=Chronic valve disease= is thus found to be a common result of endocarditis, and from the obstacle presented to the flow of blood through the different cardiac orifices by the rigid, inelastic and distorted valves, hypertrophy of the heart frequently supervenes.

In our domestic quadrupeds ante-mortem clots and fibrinous polypi have been chiefly formed in the right side of the heart, and diseased valves in the left.

_Symptoms._ The general symptoms agree in many respects with those of _pericarditis_. There are the same general symptoms of fever (temperature 102° to 106°), the same pinched, anxious countenance, the same shortness of breath and oppression when moved, the same violent heart’s action, and the same rapid, excitable pulse tending to be irregular and intermittent. Among the more specific symptoms are a very violent impulse of the heart against the left side, varying in force, however, in successive beats; a metallic tinkling accompanying the impulse and sometimes heard at some little distance from the body, a blowing murmur as soon as the changes in the valves render them insufficient to close the orifices, and, if the obstruction exists on the right side, venous pulse, general venous congestion, and dropsical swellings.

The pulse may at first have considerable force but, as insufficiency of the valves ensues, it becomes small and weak, its weakness forming a most marked contrast to the violence of the heart’s impulse against the side. The irregularity and intermission of the pulse is to be ascribed at first to the impaired nervous energy of the heart though later it is often due to the obstacle presented by clots to the flow of blood from the heart, so that a beat sometimes takes place without a corresponding pulsation. It may reach 80 or 160 per minute in horse or ox.

The blowing murmur when heard is one of the most characteristic symptoms but must be carefully distinguished from other allied heart sounds. If very loud it may be confounded with the friction sound of pericarditis, but may be differentiated by its invariable coincidence with some particular portion of the heart’s beat. The absence of local tenderness is another distinctive symptom. Again in pericarditis effusion takes place early annulling friction sound, and diminishing alike the impulse and the sounds of the heart.

It is of less practical value to be able to distinguish the precise seat of the murmur, yet the following data will guide to such a conclusion.

=Simple induration or insufficiency of the Left Auriculoventricular (Mitral) valve.= Paroxysms of palpitation, oppression, and difficulty of breathing; vertigo with loss of control over the limbs and vacillating gait; stupor, coma; slight tremor and blowing noise with the first sound of the heart; heart’s impulse, violent, but irregular in force, sometimes double; pulse feeble, irregular, unequal, or intermittent; sometimes though not at all constantly a venous pulse in the lower end of the jugulars. In chronic induration of this valve, or in osseous, or cartilaginous degeneration the same symptoms are shown. The more general symptoms may, however, require exercise to develop them.

=Induration, etc., of the Right Auriculo-Ventricular (tricuspid) valve.= The symptoms are almost identical with the last. Venous pulse is constant, and, particularly after exertion, the veins generally are distended. Dropsies are more common.

=Narrowing of the Mitral orifice.= In addition to the same general symptoms as the last named lesions, there is a sighing, blowing, purring or rasping sound, according to the degree of narrowing, heard _before_ the first sound of the heart. It is the noise of the blood rushing through the narrowed orifice between auricle and ventricle. It is usually loudest behind the middle of the shoulder on the left side. Feeble pulse, frequent imminence of suffocation and filling of the limbs, etc., are nearly constant.

=Narrowing of the Tricuspid orifice.= Symptoms nearly identical with the last. Venous pulse more constant. Blowing murmur sometimes loudest on the _right_ side of the chest.

=Induration or insufficiency of the aortic valves.= Blowing murmur with the second sound of the heart. Double rushing sound in the carotid with each heart’s beat. There is an appreciable interval between the beat of the heart and corresponding pulsation at the jaw.

=Induration or insufficiency of the pulmonary valves.= Blowing murmur with the second heart sound, but no corresponding double sound in the carotid, nor any marked retarding of the pulse.

=Loose coagula in the heart= or _adherent ones_ (_polypi_) produce one or other of the above class of symptoms, according to the particular orifice they tend to block or the valves whose function they impair.

Anæmia and leukæmia may have blowing murmurs with the first or second heart sound.

=Embolism.= =Plugging of arteries.= Another class of symptoms sometimes supervenes because of loose clots being washed on into the arteries, and blocking them when they reach those that are too small to transmit them. These symptoms will be as varied as the organs whose arteries are plugged. If in the brain there may be dulness, stupor, vertigo, somnolence, delirium; if in the liver, biliary and digestive derangement; if in the lungs, cough with the other signs of pneumonia and abscess; and if in the limbs lameness and paralysis, (brought on or aggravated by exercise, and often removed by a few minutes’ rest), wasting of the muscles, etc. (_See Embolism_).

_Causes._ These are in the main the same as those of _pericarditis_. Weak health, exposure to extremes of weather, punctures with foreign bodies, but above all, the rheumatic constitution are common causes. Indeed rheumatism appears more prone to attack the serous membrane lining the heart cavities than that enveloping it externally. One reason for this is to be found in the great and incessantly recurring strain on the fibrous structure of the valves, and particularly in hard worked horses and hunting dogs in which the strain is often extreme. It has been argued that the increased blood pressure caused by digitalis is an appreciable cause. Its frequent connection with rheumatism is shown in the rheumatic lesions of joints and fibrous structures seen in carcasses dead of endocarditis.

Diseases in the muscular substance of the heart as cysts, abscess, etc., frequently extend to the endocardium.

Among other causes must be mentioned disease-changes in the blood. These may act on the valves directly as in the case of lactic acid injected by Dr. Richardson, into the peritoneum with the view of producing rheumatism and successfully as regards the lesions of the cardiac valves; or indirectly by determining coagulation and irritation of the lining membrane coming into contact with the clot. The very fibrinous and plastic state of the blood in extensive inflammations is a probable cause of the occurrence of clots in the heart, and the frequency of such clots in the dog has been ascribed to the plasticity of his blood (Leblanc). The injection of pus into the blood or the absorption of microbes from diseased surfaces will sometimes produce ulcerative disease of the valves. The same is true as regards the germs of omphalitis, pneumonia, arthritis and other infectious diseases.

Lafosse records certain cases of endocarditis due to extension of the disease from inflamed veins.

_Prognosis._ Endocarditis is always attended with great danger to life, but it is more likely to terminate in chronic valvular disease which quite unfits the animal for useful work. Mild cases may terminate in complete recovery.

_Treatment._ This is in the main the same as that adopted in the early stages of pericarditis. Absolute rest is of prime importance. Laxatives, sedatives and counterirritants are to be mainly relied upon. Belladonna and chloroform on the chest behind the left elbow may be used. As there is not the same danger from effusion, diuretics need not be pushed to the same extent. Digitalis must be avoided if possible until the high fever subsides. In infective cases, quinia, salicylate of soda, salol, or hyposulphite of soda may be given. Later give tincture of muriate of iron.

In rhemuatic cases, treat as for an acute attack of rheumatism. Frequent large doses of salicylate of soda or salol, large doses of acetate of potass and colchicum, warm clothing and counterirritants to the region of the heart are especially demanded. (See Rheumatism.)

When clots are suspected, and when endocarditis threatens to lapse into the chronic form, it is recommended to give iodide of potassium (horse and ox 1 drachm, dog 5 grains, twice daily) with carbonate of ammonia or of potass and bitter tonics. A lengthened rest after apparent recovery is essential to avoid permanent valve lesions.

CARDITIS. MYOCARDITIS.

Definition. Rare. Complicates pericarditis and endocarditis, wounds of
the heart, and tubercular and other deposits. Symptoms. Treatment.

_Definition._ Inflammation of the muscular substance of the heart.

This is a rare affection and is necessarily limited to a small portion of the heart’s substance, otherwise, the cardiac contractions must cease in obedience to the general law that the normal function of an inflamed organ is for the time abolished. It is mainly seen as a concomitant of endocarditis or pericarditis, and extends only to the superficial muscular layers; or it results from a wound as in the penetration of the heart by a needle or other sharp pointed body and is then equally circumscribed. It has been seen as a complication in infectious diseases—aphthous fever, pyæmia, septicæmia, pneumonia and tuberculosis.

The evidences of the existence of carditis are chiefly the lesions met with after death. 1st, The existence of abscesses in the heart’s substance associated with polypus (Gowing, Leblanc, etc.,) or otherwise (Reynal). Also diffuse suppuration in the heart’s substance (Puze, etc.) 2nd, Softening of the muscular substance, a state occasionally met with when an animal has died of ruptured heart. 3d, Ulceration of the walls of the heart as reported by Mercier in a case of endocarditis. 4th, Transformation, and induration of the heart’s substance whether into fibrous tissue, cartilage or bone. This last condition of the walls of the right auricle and ventricle has been repeatedly seen in old horses, the change being in certain cases so extensive that one is left in wonder as to how circulation could have been carried on. Three specimens of this kind were preserved in the museum of the Alfort Veterinary College, Paris, and the Royal Veterinary College, London. Lafosse records two cases of gangrene of the internal layers of muscle in endocarditis.

The _symptoms_ are those of acute heart disease generally modified somewhat by the precise location of the inflamed spot, and _treatment_ need not differ materially from that applied for inflammation of the investing membranes, inner and outer, and for the infectious disease which it complicates.

CHRONIC VALVULAR DISEASE OF THE HEART.

This, as already noticed, is a common result of endocarditis, the valves being most obnoxious to disease in such cases. The _symptoms_ are those mentioned under endocarditis as characterizing disease of the different valves, such as incapacity for exertion, difficult breathing, palpitation, irregularity or intermission of pulse, venous pulse, abnormal heart sounds, unsteadiness of the limbs when driven, and dropsical swellings in the limbs and elsewhere. The reader is referred to endocarditis for particulars, it being borne in mind that these symptoms are not in this case associated with fever.

Horses affected in this way are useless. Cattle may sometimes be partially fattened by preserving them from all sources of excitement, by keeping the bowels regular and by combating any paroxysms with sedatives, such as aconite, veratrum, hydrocyanic acid, or opium, and with digitalis.

FATTY DEGENERATION OF THE HEART.

Causes, improvement in the direction of easy fattening, inactive life,
best breeds of butcher cattle and pigs suffer. Symptoms, weak,
irregular, intermittent pulse, palpitation, unfitness for exertion,
general heart symptoms.

In addition to the fibrous and bony transformations to which the substance of the heart’s walls is subject, a fatty metamorphosis is frequently met with. In most cases the fat accumulates in great masses externally, but in others the muscular tissue has to a greater or less extent lost its natural structure and fatty granules have taken the place of the sarcous elements. In overfed oxen the right cavities of the heart rarely escape dilatation, and this condition is very often accompanied by the fatty change. Virchow has shown that highbred English pigs imported into Germany are subject to a similar affection of the heart and of the entire muscular system. It may occur during wasting diseases and from phosphorous poisoning.

The _symptoms_ are weak, irregular and intermitting pulse, palpitation on excitement, weakness of the heart’s impulse in the intervals, incapacity for exertion, sighing, Cheyne-Stokes respiration, loss of control over the limbs when hurriedly driven and tendency to dropsy. It is often associated with dilatation, is rarely distinguishable from it in life, and is equally beyond remedial measures. The feeding animals most commonly affected can usually be fattened if removed from all sources of excitement. In case of phosphorous poisoning improvement takes place when the poison is stopped.

NEW FORMATIONS IN THE HEART. TUMORS. PARASITES.

Glanders, abscess, melanosis, tubercle, polypus, nœvus,
parasites—echinococcus, cysticercus tenuicollis, cysticercus
cellulosa, trichina, sarcocyst, filaria immitis, strongylus subulatus,
strongylus vasorum.

1st. =Deposits of Glanders.= In many cases of glanders and farcy in horses the specific product is deposited in the heart as well as in other internal organs. Such deposits are small but numerous, infiltrating the muscular tissue; their cut surface is dry, finely granular and of a yellowish white color.

2d. =Abscesses= are sometimes formed in the heart from the colonization of microbes from suppurating surfaces.

3d. =Cancer of the heart= has been noticed chiefly in dogs by Leblanc. It occurs only consecutively to cancer in other parts of the body, yet it has sometimes acquired considerable dimensions and interfered materially with the movements of the heart.

4th. =Melanosis= of the heart has been repeatedly noticed in the horse. Some if not all such cases should be classed with cancers, as these internal deposits of black coloring matter in solipedes, have, in our experience, mostly possessed malignant characters, though they are usually simple tumors as developed in the skin of the horse. These black masses usually project beneath the pericardium or endocardium.

5th. =Tuberculous deposits= have been met with in the substance of the heart in cases in which the lungs or other organ were the seat of this disease.

6th. The _fibrous growths_ or _polypi_ due to the deposition and organization of fibrinous material from the blood have been referred to under _endocarditis_.

7th. Gamgee reports the existence of a vascular tumour of the right ventricle of a horse in the museum of the Turin Veterinary School. It consisted of varicose veins ramifying beneath the endocardium which in its turn was healthy.

8th. The =parasites found in the heart= are various, _a._ One, the =Echinococcus Veterinorum=, has been repeatedly found in the substance of the heart or projecting from its inner or outer surface. _b._ Another, the =cysticercus tenuicollis=, has been met with in the pericardial sac of a calf (Reed). _c._ A third, the =cysticercus cellulosa= infests the muscular structure of the heart of measly pigs. _d._ The heart like other voluntary muscles of hogs occasionally contains =trichina spiralis=. _e._ =Rainey’s cysts= (=sarcocysts=) are microscopic ovoid bodies usually found in the hearts of oxen and other animals. _f._ A round worm, =filaria immitis=, first described as filaria papillosa hæmatica by Delafond and Gruby, lives in the blood of the dog, is one millimeter thick by fifteen to 30 centimeters long. It may obstruct the pulmonary artery (Serres) or the mitral orifice (Silvestre). It may cause various nervous disorders and even sudden death. Its mode of entrance is unknown. _g._ =Strongylus Subulatus=, 1 to 2 mm. long by 70 to 90 μ. in thickness was found in numbers in a nodule of a dog’s lung, and the dorsal vein of the penis of a dog (Leisering). _h._ =Strongylus Vasorum= in the right auricle and ventricle of a dog, in pea-like blood clots. It is 14 to 21 mm. long by 1 m. in thickness (Serres).

RUPTURE OF THE HEART.

In the lower animals ruptures of the heart have been observed as the result of (a) extraordinary exertion, (b) violent concussion, and (c) ulceration and degeneration. The rupture of the fatty heart in the lower animals is not common.

=Rupture during severe exertion= occurs in the perfectly healthy heart. The ruptures take place in the weakest point, and most commonly in the fibrous ring which encircles the base of the heart and attaches the great aorta. This is occasionally seen to happen in very spirited horses during a severely contested race or when a heavy load is being dragged up hill. Percivall mentions the case of a horse at a Woolich racing meeting, which had just lost a heat by half a head and which died just after passing the winning post, with ruptured right auricle.

Cases occur during coitus (Hering), tympany (Anacker, Mayer, Perdan) and operations (Stockfleth).

=Rupture from Concussion= more frequently implicates the muscular walls which have not the same power of resistance when they receive the blow in a relaxed condition. Parker met with a case of rupture of the right auricle at its base or at the line of its union with the ventricle. The subject was a pony which ran away down hill and struck his right shoulder violently against a cart wheel. In other instances the rupture takes place in the posterior vena cava, and particularly if its walls have been the seat of disease. Gamgee found rupture of the commencement of the azygos vein in oxen killed by pithing in the slaughter houses of Ferrara, and Professor Maffei subsequently found that out of 3095 oxen killed in these abattoirs 57 had this vein ruptured. Gamgee’s explanation of the occurrence is that “the instant the animals are pithed the walls and contents of the chest become paralyzed, the heart becomes an inert bag filled with fluid, the jerk of which as the animal falls, causes rupture of the containing vessel at its weakest part and this is in truth the vena azygos whose walls are thin and only protected externally by the pleura.” Hertwig gives other cases resulting from falls.

=Perforation of the heart from ulceration= is sometimes seen in cows when sharp pointed metallic bodies from the stomach make their way into its substance. An alleged case of rupture following ulceration of the walls of the right ventricle is recorded by Gaullet.

Inflammation, softening, fatty and calcareous degeneration, dilatation, atheroma, and the presence of parasitis in its substance render the heart more friable and predispose to rupture.

_Lesion._ The rupture is often at the fibrous ring encircling the aorta or pulmonary artery; in other cases in the muscular wall of ventricle or auricle.

_Symptoms._ Death may be practically instantaneous. If delayed there is hurried breathing, anxiety, weakness, pallor of the mucous membranes, staggering, trembling, vertigo, stupor, and convulsions.

DISEASES OF ARTERIES.

The chief morbid conditions seen in arteries are: Wounds, inflammation, thrombosis, embolism, degeneration, and aneurisms. Wounds belong essentially to surgery.

ARTERITIS. EMBOLISM.

Internal and external arteritis. Thrombosis, from inflammation.
Embolism. Bruising. Stretching. Ligature. Lesions. Extension of clot,
color, consistency, adhesion, lamination. Composition of clot.
Condition of vessel. Changes in muscles. Causes: muscular tension,
embolism. Heart clots, venous clots. Infecting debris. Symptoms:
paresis or paralysis on exertion. Local suffering, tenderness, firm
swollen artery, derangement of nutrition and function, atrophy.
Chronic arteritis: Atheroma. Changes in serosa. Fibrous thickening,
atrophy, dilatation. Strongylus. Treatment: rest, anodynes, alkalies,
massage.

_Inflammation of arteries_ has been divided into _external_ and _internal_ arteritis, according as it affects the fibrous sheath of the artery or its inner lining membrane.

In =external arteritis= the exudation of lymph often forms a protecting layer around the vessel, while the inner coats continuing sound the current of blood remains unimpaired. Even when suppuration takes place in the vicinity of a large artery, that vessel may pass through the center of the abscess and convey the blood as freely as before. The nutrition of the vessel thus detached from the surrounding tissues is maintained by its accompanying nutrient artery, though if the abscess is large there is danger of a deficient supply. The frequent presence of such arteries traversing an abscess should make the surgeon careful how he breaks down the bright pink bands occasionally seen to stretch across such cavities.

=Internal arteritis=, or _inflammation of the internal coat of an artery_ is incomparably more serious and mainly because it determines the coagulation of the contained blood and consequent _plugging_ of the vessel. This is but one manifestation of the general law that in inflamed tissues the fibrine-forming elements are produced in excess, and when blood comes in contact with these it tends to coagulate (thrombosis). On the other hand the inflammation in the arterial coats may ensue from the pressure of a blood clot formed in the veins or heart and carried on with the current until it reaches an artery too small to admit it (embolism).

The inflammation may be confined to a limited space as when an artery is bruised, stretched so as to tear through its inner coats, or interrupted by a ligature. It may on the other hand be diffused over a greater extent of the vessel, and in some cases two inflamed portions are separated by intervals of sound artery.

=Anatomical features of the inflamed artery.= In active inflammation of the internal coats of an artery, it contains blood clots, and if the inflamed surface is not very limited in extent the vessel is completely plugged and the clot forms up to its nearest transverse branch on the cardiac side, precisely as if the artery had been tied. The resulting clot is sometimes tubular, so that an impaired circulation is still carried on. The clot varies in length according to the extent of vessel inflamed, or the distance from the inflamed spot to the nearest diverging branch. The clot is usually fusiform in outline and is firmly attached throughout more or less of its diameter, and occasionally so firmly that it is all but inseparable from the serous membrane. The narrowed ends of the clot mostly float free in the liquid blood and portions from the end most distant from the heart will sometimes get detached, and by blocking up smaller arteries give rise to new centres of disease. This is a true instance of _embolism_ or _plugging_.

The clot has nearly always a grayish or yellowish white color in the larger vessels, such as the posterior aorta, and an uniform pink or red streaked with yellow in the small. It is possessed of great firmness and elasticity. That portion of the surface which was not attached to the arterial walls, during life, is clear, smooth and glistening, while the portion which adhered to these walls is rough, irregular, and broken into shreds. It is usually composed of concentric layers showing its mode of formation.

Clots of this kind analyzed by M. M. Lassaigne and Clement were composed of water 74 parts; fibrine and albumen 25 parts; and alkaline salts 1 part.

The vessels filled by these clots are very irregular in their outline being thick and bulging at one point and thin and constricted at another. The outer coat is rarely the seat of morbid change, though it sometimes shows branching redness and thickening from exuded lymph. The internal coat where the clot was attached is intensely and unnaturally red, and a rough granular surface has given place to the healthy, smooth glistening appearance. In old standing cases the clots can only be separated from such surfaces by dissection with the knife. Other portions of the surface than those to which the clot adheres are usually smooth and polished, though rough granular and injected patches are sometimes met with independently of clots.

The muscles formerly supplied with blood by the obstructed arteries are pale, discolored, unnaturally firm, and if some time has elapsed since the plugging their fibrillated structure is made out with difficulty.

_Causes._ The causes of arteritis are often obscure. Goubaux conceived that it was frequently determined by extreme muscular tension. In support of this view he adduced the facts that it has been mainly observed in the horse, in which such stretching of the muscles is greatest, and that its most common seats have been where the muscles and vessels are most liable to stretching. Thus it is frequent in the posterior aorta towards its termination or in other words where the adjacent muscles (psoæ) are very liable to laceration from slipping backward or from efforts to disengage the limbs when fixed in soft ground; the femoral and auxiliary arteries are likewise frequent seats of inflammation and are likely to be overstretched when the limbs slip outwards.

=Embolism= or =Plugging= of the arteries must be accepted as another cause. This is referred to under _endocarditis_, as an occasional consequence of the detachment of clots and fibrinous substances from the internal membrane of the heart. The detached mass in this case passes from the heart into the aorta and thence through its divisions until it reaches a vessel too small to receive it, when it is at once arrested and determines inflammatory action in the plugged vessel. When arrested in some soft organ such as the lungs, liver or brain the resulting inflammation often gives rise to extensive suppuration and abscess. In other situations its effects may be confined to inflammation, the shutting off, of blood from particular parts, the impairment or loss of their function and nutrition, and finally atrophy and degeneration.