CHAPTER V.—PART I.
DISEASES OF THE CIRCULATORY SYSTEM
Structure and Action of the Heart
Before entering on a description of the diseases of the Heart, it may be well to give a brief description of that organ and its functions, for the benefit of non-professional readers.
The heart is placed in the center of the thorax, in the space between the lungs, and opposite the third, fourth, fifth and sixth ribs. It may be described as a muscular forcing pump, for the transmission of blood to all parts of the body. The texture of the heart is muscular, with tendinous or cartilaginous bands around the openings between the auricles and ventricles, and between the latter and the arteries. It contains four chambers, viz.: two auricles and two ventricles; each auricle communicates with its corresponding ventricle; but the auricles do not communicate with each other, nor do the ventricles. The opening in each pair is guarded by a little valve, in order to ensure the flow of blood in one direction, and to prevent any regurgitation or re-flow from the ventricles into the auricles. We find valves for a similar purpose placed at the origin of the pulmonary artery and the aorta, which proceed from the right and left ventricles, and are the channels by which the blood flows through the former to the lungs, through the latter to the general circulation. The chambers of the heart are lined by a smooth membrane of a serous character, called the endocardium, which is often the seat of disease; and the whole is enclosed in a fibro-serous sac, called the pericardium.
On examining the heart, it will be found externally divided by a furrow, which corresponds with a muscular septum, dividing the organ into two parts, or two hearts, having no direct communication with one another, except in the fetus. The right side, whose parts are thinner than the left, may be called the venous heart, as it receives the blood in an impure state from the veins, and transmits it through the pulmonary arteries to the lungs, where it becomes exposed to the atmosphere, and converted from venous into arterial blood. It is then conveyed by the pulmonary arteries to the left auricle and ventricle, whence it is propelled through the aorta and its branches to all parts of the body.
The dimension and weight of a healthy heart vary so much that it is not possible to give them accurately, but the average is stated as follows by Mr. Walsh: “It is about ten and a quarter inches from the base to the apex, seven inches in its antero-posterior diameter, and five and a quarter from side to side. In weight, it varies from six and a half to seven pounds. The auricles have much thinner walls than the ventricles, and the muscular substance or the left ventricle, occupying the apex of the heart, is very much thicker than that of the right.”
The nerves which supply the heart are the pneumogastric and sympathetic.
Idiopathic disease of the heart in the equine race is a very rare occurrence; but, as a consequence or accompaniment of influenza and fevers of a low type, is by no means uncommon; it is therefore of importance that we should know how to diagnose both the organic and functional derangement of so important an organ, which can only be done by making ourselves familiar with.
THE ACTION OF THE HEART IN HEALTH.—There are three means by which this knowledge may be attained: first, by _Percussion_, which, in the human subject, affords an index to the size and position of the heart; but in consequence of the less exposed position of that organ in the horse, is of little value, except in diagnosing Hydrops Pericardii. Second, by _Impulse_, or the force of the beat imparted to the hand placed flat on the near side of the chest, just behind the elbow. Third, by _Auscultation_, which is the only reliable way of ascertaining the condition of the heart, and consists in placing one ear, or a stethoscope, in the same position as that already described. Two distinct sounds can be heard; the first, termed the “systolic,” is louder and more prolonged than the second (which immediately follows), and seems to depend upon the contraction of the ventricle; during this contraction the organ elongates and rotates on its axis from right to left, thus producing the impulse and sound on the left side of the thorax. The second, “diastolic,” or “flapping,” sound, cannot be heard in a fat, circular-chested horse; it is supposed to arise from the regurgitation of the blood, which is in the aorta and pulmonary arteries, forcibly closing the valves placed at their origin in the ventricles, so as to prevent the blood coming back into the heart. These sounds together form what is called the “beat,” and are succeeded by a brief interval of repose. In the healthy animal these beats are uniform and regular, corresponding with the pulse; but in disease there may be, first, increase or diminution in the frequency and strength of the beats; second, irregular or intermittent action of the heart. In the latter case, we hear two or three beats in quick succession, and then a longer interval of repose than is natural, followed by the consecutive, quick beats and long repose, the number of the former and duration of the latter being singularly uniform. Third, the systolic and diastolic sounds may increase, diminish, or be succeeded by other sounds indicative of disease hereafter described.
Pericarditis—Dropsy of the Heart
DEFINITION.—Inflammation of the fibro-serous membrane which invests the heart, causing the effusion of a serous fluid. It occurs as a primary affection and as a complication in Influenza, Rheumatism and other constitutional diseases.
CAUSES.—When met with in an idiopathic form, which is very rare, it may depend upon exposure to damp, cold, changes of temperature, and those unhealthy conditions which also cause acute diseases of the respiratory organs. It may also arise from a sudden change from low, to rich heating food, or from the field to a hot stable. But it usually occurs as an accompaniment of Pleurisy or Rheumatism.
SYMPTOMS.—The horse stands quiet, showing signs of pain and anguish, with sunken head, anxious expression in the face, dilated nostrils, frequent (100 to 120), wiry, and sometimes IRREGULAR or intermittent PULSE, and general intense fever.
The breathing is also accelerated (36) and difficult, and is accompanied by a movement of the flank similar to that seen in broken wind, and by a deep depression along the margin of the costal cartilages. In the early stages, pressure on the left side, and smart percussion in the region of the heart, cause flinching and expression of pain; and auscultation, _before exudation has taken place_, reveals friction—_to and fro_—sounds. These sounds are, however, not uniformly present in this disorder, nor is their presence an unquestionable proof of its existence, for similar sounds may be do to pleural disease, the latter being characterized by synchronism with the respiratory movements. The friction sounds are therefore of little value, except as concurrent with other symptoms. They also cease when exudation or adhesion has taken place; then the heart’s beats are muffled. In the later stages, the heart, which at first palpitates, soon becomes fluttering and uncertain in its beat, conveying a peculiar pulsation to the hand, not easily to be described. No impulse can be felt when the effusion is considerable. Percussion gives a dull sound over the region of the heart, but not so in other parts of the chest, where the respiratory and bronchial sounds may be heard, thus distinguishing Hydrops Percardii from Hydrothorax. The breathing gradually becomes more distressing, and movement aggravates the distress; the pulse more feeble and even imperceptible at the jaw; the ears and legs cold; the legs, sheath, chest, abdomen, etc., œdematous; and the general wasting rapid till death ensues.
DIAGNOSIS.—The friction sounds, and pain on percussion in the region of the heart, with irregularity in its beats, and a peculiarly anxious expression of countenance, are the principal pathognomic symptoms—to which Delafond adds dyspnœa, attended by an action of the flank like that of a broken winded horse. The great difficulty is to distinguish this disease from Pleurisy, which may be done by accurately marking the period at which the frictional sounds occur, viz.: during the systole or beat of the heart, whereas for Pleuritis we hear it during the respiratory movements of the lungs. When the pericardial fluid becomes much increased, the friction sound ceases, as does also the impulse of the heart, which at first usually palpitates, then becomes fluttering, feeble, and intermittent, and at last can with difficulty be heard. Percussion gives a dull sound in the region of the heart, but just behind it, as well as in other parts of the lungs; if there is no disease in them, or Hydrothorax, the resonance in those parts will serve to distinguish Hydrops Pericardii from Hydrothorax.
PROGNOSIS.—In the strong, and in the majority of cases, favorable.
TREATMENT.—A.A., given every three hours, and later, four times per day, will be proper.
Endocarditis
DEFINITION.—Inflammation of the fibro-serous membrane which lines the heart.
This is a very common complication in Rheumatism, and is very acute and dangerous; the danger arising less from the fatality of the acute stage, than from the lesions which are consequent upon it.
SYMPTOMS.—In Endocarditis the contractions of the heart are energetic, vibratory, and often irregular; the pulse is also irregular, and frequently intermittent, and there is a contrast between the feebleness of the pulse and the violence of the heart beats. Leblanc states that this last symptom is characteristic of Endocarditis. He has also observed a loud metallic tinkling, and a _bruit de souffle_, or sound like the blowing of a pair of bellows, or a sawing noise, like bronchial respiration, accompanying the systole of the heart. In the early stages, the breathing is not so difficult as in Pericarditis; but if the auriculo-ventricular valves are thickened, it becomes distressing. Sometimes the whole of the membrane is thickened; in other cases the lesion is limited; in others, the abnormal growth forms a cardiac Polypus, which may grow to an enormous size. The legs are usually cold.
PATHOLOGY.—The endocardium, although a serous membrane, is mixed with fibrous elastic tissue at its valvular reduplications, which accounts for the disease being so frequently associated with rheumatism, and for the morbid appearances more commonly witnessed in the valvular structure of the heart than elsewhere. The natural result of inflammation in this, as in other serous membranes, is the effusion of lymph, and consequent thickening, which sometimes interferes with the play of the valves, or narrows the auriculo-ventricular openings, thus producing the bellows-sound which has been described as one of the chief symptoms. The inflammation may extend to the muscular substance of the heart, which becomes darkened in color and easily broken down; while in some cases large quantities of fibrin are thrown out, which quite block up the auriculo-ventricular openings and orifices of the large blood-vessels. To Endocarditis may also be traced Tumors and Polypi, as well as Hypertrophy and Dilatation. Abscess in the walls of the heart has also been observed as a consequence of Endocarditis.
DIAGNOSIS.—The pathognomic symptoms of Endocarditis are frequently very obscure, being like those of Pericarditis; but it is of very little consequence, as the treatment must be similar. However, the bellows-sound in the former, and the friction sound in the latter, are sufficient in the majority of cases to point out the nature of the disease when taken in connection with other symptoms which have been mentioned.
PROGNOSIS.—Owing to the various terminations of Endocarditis, nearly all of a serious character, our opinion as to the ultimate result must be unfavorable, although in the majority of cases the animal appears to recover; but he is found afterwards not as good in his wind as formerly, easily distressed, and when going at an ordinary pace with hounds, will probably fall down and expire suddenly. A.A. will be our best resource.
Hypertrophy—Enlargement of the Heart
DEFINITION.—An abnormal growth of the muscular tissue of the heart by thickening of the walls.
VARIETIES.—There are three. Simple Hypertrophy is the thickening of the walls without any change in the capacity of the cavities. Eccentric Hypertrophy is the thickening of the walls with dilatation of the cavities. Concentric Hypertrophy is the thickening of the walls with diminution of the cavities. The lesion is usually associated with other diseases, and especially with affections of the lungs.
The disorder is slow in its progress, though it soon interferes with the working capacity of the animal. It predisposes to other lesions, such as congestion of the lungs, hemorrhage, etc.
CAUSES.—Excessive effort of the heart to overcome obstruction to its action; constriction of the vessels and of the openings between the different cavities of the heart; deposits on the semi lunar valves; Aneurism of the aorta or the pulmonary artery; excessive physical exertion and consequent exhaustion of the heart. Mr. Pritchard remarks that “horses, particularly those employed in quick draught, are commonly called on to perform arduous tasks with full stomachs, by which the free action of the lungs is considerably impeded; thus, obstruction being given to the circulation through the pulmonary vessels, corresponding increase of force in the action of the heart is the consequence.” Hypertrophy has been often observed in broken winded horses.
SYMPTOMS.—Strong, impulsive movement of the heart, which remains constant; intensity of sound, with a loud, hollow thumping beat; a metallic _bruit_ or “clack”; irregularity of rhythm; dullness on percussion. The horse is easily distressed, palpitation comes on with ordinary quick work, and there is an anxious expression in his eye on these occasions, which leads us to suspect that there is something amiss with the animal. These symptoms are attended with languor, coldness of legs and ears, dyspnœa, giddiness or Megrims, loss of appetite, and, in a later stage of the disease, with œdematous swelling of the chest, abdomen, and extremities.
PATHOLOGY.—The thickening of the walls of the heart may be regarded as a beautiful provision of nature to strengthen the organ and enable it to overcome the obstacle which exists to the free circulation of blood through it. The thickening of the muscle depends upon excess of nutrition consequent on increased action; similar to the change in the biceps muscle of the blacksmith’s arm from hard work.
It may be an idiopathic disease not dependent on obstruction; but such cases are very rare. The obstruction will usually be found to depend on disease of some of the valves, or constriction of the aorta or pulmonary artery at its origin. The Hypertrophy may be general, or we may find only one auricle or ventricle (generally the latter) whose walls are thickened.
DIAGNOSIS.—The increased impulse of the heart, especially after quick work; the irregularity of the pulse and thick wind, without any lung disease being present; and the dullness on percussion over the cardiac region, are the chief pathognomic symptoms.
PROGNOSIS.—Although the disease is incurable, a horse may live for years with enlarged heart.
TREATMENT.—Doses of A.A. will be of value in conjunction with only moderate work and good care.
Atrophy of the Heart
DEFINITION.—Emaciation or wasting away of the walls of the heart.
CAUSES.—Similar to those of dilatation. Loss of nervous power through the degenerating influence of fevers induces Atrophy by weakening the muscular fibres of the heart.
SYMPTOMS.—Feeble impulse of the heart, with louder sounds than are usually heard on applying the ear to the chest. The pulse is generally slow, feeble and intermittent. The veins in the neck may also be observed to pulsate. The animal is dull and fastidious in his appetite; dropsical swellings appear on the chest and belly; the legs become cold or œdematous. There is difficulty in breathing on the slightest exertion, and sometimes palpitation or fluttering of the heart.
PATHOLOGY.—There are two forms of Atrophy, one in which there is a wasted and flabby appearance of the organ, whose parietes are so weak that when removed from the body it does not retain the rounded symmetry of a natural heart, but becomes a shapeless mass when thrown on the ground. This form of Atrophy was frequently met with during the prevalence of the Cattle Plague, and it has been observed in connection with some forms of Influenza. The second form of Atrophy is termed Fatty Degeneration of the heart. Of this there are two varieties. In one the fat grows on the surface of the organ, encroaching on and insinuating itself between the muscular fibres, impoverishing them, and ultimately causing them to waste; the result is that the muscular walls become thin. In the other variety, fat in a molecular form takes the place of the muscular element, and ultimately fills the sheaths, which previously contained muscular fibre.
Dilatation of the Heart
DEFINITION.—Enlargement of one or more of the cavities of the heart.
CAUSES.—Some defect in the valvular apparatus, allowing the blood to regurgitate and to distend the cavity, which, by pressure on the walls, causes absorption and attenuation; loss of power in the nervous system; fevers of a sthenic or typhoid character, which weaken the muscular fibres.
SYMPTOMS.—The action of the heart is feeble and tremulous; the pulse small, soft and weak; the least exertion brings on Dyspnœa; there are languor, giddiness, or “Megrims”; the horse is “off his food”; the ears and legs are cold; and ultimately there is œdema of the legs, belly and chest.
PATHOLOGY.—Dilatation may exist either with Hypertrophy or with Atrophy of the walls of the heart, and in the latter case is most probably an effect of the emaciated state of the muscular substance of the heart, which allows the blood to accumulate, and to distend one or more of the auricles or ventricles.
TREATMENT.—Dilatation and atrophy of the heart admit of very little help in the majority of cases, moderate work and occasional or daily use of A.A., will be proper, and do something towards improving the condition and prolonging the usefulness of the animal.
Palpitation
DEFINITION.—An abnormal increase in the action of the heart.
Irregularity in the action of the heart is a functional derangement, and not do to organic disease. It occurs in horses that are in feeble health and out of condition, or that have been subject to severe and straining exercise, such as pulling a heavy load uphill or running hard with the hounds.
Anemic Palpitation
CAUSE.—Poverty of blood.
SYMPTOMS.—A dull, thumping sound is heard to proceed from the cavity of the chest, which, in extreme cases, may be heard on both sides, and may even be audible at a distance of some yards, corresponding to the beatings of the heart and pulse; tumultuous breathing, redness of the mucous membranes, increased temperature of the body. Auscultation will detect blood sounds in the neighborhood of the heart, large arteries, and veins. These “anemic murmurs” vary with the condition of the blood, and are caused by its “churning” as it passes through the traversing channels of the heart. They constitute a continuous hum, or the “_bruit de diable_” of the French. In some cases the action of the heart is so great that it causes shaking or jerking of the whole body.
PROGNOSIS.—When the palpitation does not proceed from any organic disease, we may expect to remove it in a very short time by appropriate homeopathic remedies. A dose of A.A. often relieves an attack.
DIFFERENCES BETWEEN SO CALLED SPASM OF THE DIAPHRAGM (PALPITATION) AND TRUE SPASM OF THE DIAPHRAGM (HICCOUGH). ──────────────────────────────────┬────────────────────────────────── SO CALLED SPASM OF THE DIAPHRAGM.│ TRUE SPASM OF THE DIAPHRAGM. ──────────────────────────────────┼────────────────────────────────── Hiccough is seldom present. │Hiccough is always present. The action of the abdominal │The action of the abdominal muscles is increased and the │muscles at the flank is heaving of the flanks is quite │imperceptible. visible. In those cases, where │ Palpitation occurs from a hard run│ with the hounds, the diaphragm │ becomes tired, the abdominal │ muscles come to its assistance in │ carrying on the respiration and │ the heart’s action is increased in│ order to overcome the obstacle │ which probably exists in the │ pulmonary arteries. │ The flanks are tucked up. │There is great fullness in the │flanks from the abdominal viscera │being pushed backwards.
Spasm of the Diaphragm
There is a form of palpitation which has received this designation, and has been mistaken for a functional disorder of the diaphragm, or excessive motion of the abdominal muscles. True Spasm of the Diaphragm is Hiccough; and in this condition there are no such sounds as characterize Palpitation.
CAUSE.—The excessive action of the heart, when the horse has been distressed by severe gallops or an exciting run, produces a jerking of the whole body, as the heart strikes the dorso-costal region, towards the upper part of the first false ribs.
SYMPTOMS.—These are much the same as in Anemic Palpitation; but in addition there is violent elevation of the flanks, perceptible to the observer, and, if being ridden, most unpleasant to the rider. The symptoms appear and disappear suddenly.
TREATMENT.—Give A.A. once in two hours, at first, and later three times per day.
Embolism
DEFINITION.—Distension and plugging of the arteries by solid coagulated lymph, consisting of fibrous clots, fragments of decaying or suppurating tissue, and the elements of Tubercule and Cancer.
CAUSE.—The reason why there is deposition of the offending material is unexplained; but it is brought from different parts of the circulatory system, from diseased tissues through the veins and the heart, and deposited so as to obstruct larger or smaller arteries, and thus prevent the flow of arterial blood to the limbs and organs. The arteries and hind limbs are most liable to this disorder.
SYMPTOMS.—An accurate diagnosis is not always practicable, because the disease itself is obscure. The symptoms which have been observed attending Embolism are great pain, profuse sweat, but cold extremities; quick, wiry pulse; and considerable general disturbance of health; anxious expression of face; looking round to the affected parts; rigidity and contraction of certain muscles; partial recovery and simultaneous attack of the other limb, and return of attack to the first; diminished pulse in the arteries of the implicated limb; peculiar throbbing of the posterior aorta felt through the rectum; followed by partial or complete paralysis of the limb or hind quarters; and ultimately death.
Aneurism
DEFINITION.—A tumor formed by the dilatation of an artery, or communicating with an artery, and containing blood. In the first stage the tumor contains fluid blood, and pulsates; in its second stage it contains coagulated blood, deposited in numerous thin layers, resembling the leaves of a book.
Aneurism may be idiopathic or traumatic; the latter is caused by injury to the artery. In the idiopathic or spontaneous Aneurism the dilatation may be of considerable extent, or it may be limited, with the coats of the artery intact or even thickened, or the inner coat may be attenuated and the outer one pressed outward. As the Aneurism becomes old, the coats become indurated, calcified and liable to burst. It is not an uncommon disorder in the horse, and when it occurs it is generally in the deep-seated arteries. The posterior aorta, at the origin of the anterior mesenteric artery, is very subject to Aneurism as animals grow older.
DIAGNOSIS.—This is extremely difficult, for the attendant symptoms may be readily attributed to some other malady. They often come on suddenly; the horse becomes dejected, thin, and unable to work; respiration is accelerated; pulse and heart beats are irregular; there is some stiffness in turning, or tenderness on pressure applied to the loins; swelling and cramps in the hind legs; Paralysis.
Varicose Veins
DEFINITION.—A morbid dilatation of the veins, causing a knotty, unequal swelling, so that their valves, which cannot undergo a corresponding enlargement, cease to be efficient. The effect is a retarded and imperfect flow of blood on the return to the heart.
The disease occurs most frequently in the form of a soft, elastic tumor in the saphena vein, where it passes over the inner surface of the hock joint; but it may affect another vein, or many veins. It is commonly found where the blood has been repeatedly drawn.
CAUSES.—Violent efforts in drawing; strains; inflammation set up by a prick in shoeing; frequent bloodlettings.
SYMPTOMS.—The affected veins are dilated, tortuous, knotted, and divided into separate pouches, with obliteration of the valves. Varix of the saphena at the hock joint is attended with a tumor, which gradually increases in size, is flaccid to the touch, slightly pendulous, and shaking loosely when the horse walks; becoming full and tense on pressure of the vein above it; and capable of evacuation by pressure from below upward.
TREATMENT.—Occasional doses of A.A., are beneficial.