Chapter XIII: Part 13

The _number_ of the pulse in healthy full-grown animals may be set down as follows per minute:—horse, 36 to 46; ox, 38 to 42 (with loaded paunch or in a hot stable up to 70); sheep, goat and pig 70 to 80; dog 80 to 100; cat 120 to 140; goose 110; pigeon 136; chicken 140. In old age the pulse is less frequent. This diminution may extend to 5 beats per minute in the larger quadrupeds and to 20 or even 30 in the smaller. Youth and small size again are associated with a greater rapidity of the pulse. The pulse of the foal, at birth, is about three times that of the horse; in the colt of six months it is double; at a year old about one and a half times; and at two years old one and a quarter.

The smaller the animal, _caeteris paribus_, the more rapid is the pulse. Hot buildings, exertion, fear or any other exciting cause likewise accelerates it. It is more frequent with the nervous temperament, as for example in the English race horse, or the greyhound, than in the dull lymphatic cart horse or mastiff. In advanced pregnancy it is increased in number. In the cow and mare it undergoes a monthly increase of four or five beats per minute after the sixth month. (Delafond)

Independently of these conditions a rapid pulse indicates febrile excitement attendant on active inflammatory or other disease, or a state of weakness and debility. In this last condition the heart beats more frequently to secure a more rapid circulation in the capillary blood vessels, and thus make up to the craving tissues by frequency of contact, what is wanting in the quantity and quality of the nutritive fluid. This point cannot be too much insisted upon, as the fatal doctrine that a rapid pulse indicates force of the circulation is very misleading as to treatment.

The =force and character of the pulse= differ in the various species. In the =horse= it is full, moderately tense and elastic. In the =ass= and =mule= it is smaller and harder, with an inequality of force in successive beats, and sometimes even a beat is suppressed or imperceptible. In the =ox= the pulse is full, soft and regular, appearing to roll forward beneath the fingers. In the =sheep= and =goat= the pulse is small but with a peculiar quick or sharp beat. The =pig’s= pulse is said to be firm and hard. That of the =dog= and =cat= is firm and hard coming with a sharp impulse against the finger. In the dog, however, successive beats are not always of the same force and an intermission or complete absence of a beat is by no means an indication of disease of the heart or other serious malady. It often attends the slightest excitement in a perfectly healthy animal.

In disease the _pulsations_ may become:—=frequent= or increased in number; =slow= or decreased in number; =quick= or striking with a sharp impulse against the finger; =tardy= or without sharpness of stroke and as if they rolled slowly past under the finger; =full= and =strong= when the impulse is forcible and not easily compressed by the finger; =weak=, =feeble= or =indistinct= in the opposite conditions; =small= when though perfectly distinct and forcible they are wanting in fulness; =hard=, when forcible and jarring (this is sometimes called =wiry= or, if smaller, =thready=); =soft= when though the artery may be full the beat is devoid of hardness and easily compressible so as to be unfelt; =oppressed= when with a full rounded artery, the impulse is jerking though not hard and as if the distended vessels opposed the transmission of the impulse; =jerking and receding=—=leaping=, when with empty and flaccid arteries the pulse seems to leap forward with each beat of the heart—(this pulsation may be visible to the eye in the carotids); =intermittent= when after a number of beats at regular intervals there is a complete pause extending over that period of time which would have been occupied by a full beat; =unequal= when some beats are strong and others weak; =irregular= when without any distinct intermission for a period equal to that of a single beat, the intervals between successive beats are of varying length. The pulse further has a peculiar =thrill= or =tremor= in states of great debility with deficiency of blood and imperfect filling of the vessels.

Of these the =leaping=, the =intermittent=, the =unequal= and the =irregular= pulses are of special importance in their bearing on heart diseases.

The =jerking and receding= pulse is felt in cases of imperfection of the semilunar valves at the commencement of the great aorta, and which allows blood propelled into the arteries by the contraction of the ventricle to flow back into the ventricle during its state of relaxation. This pulse is met with in other conditions as in aneurism of the aorta, but if from heart disease it is distinguished by the presence of a _blowing murmur_ with the second sound of the heart.

The =intermittent= pulse indicates functional derangement of the heart but it does not as is generally believed betoken structural disease. It is frequently observed in healthy asses and mules, and in dogs however slightly excited whether by fear or joy, or by the mere fact of their being handled, it is so common as to be almost the rule rather than the exception. It may be seen in a healthy horse as the result of excitement. During the early stages of convalescence from inflammatory affections of the lungs in the horse the pulse is often intermittent. The pulsations are at the same time unequal. There is a regular cycle of beats gradually decreasing in force and extending over a complete respiratory act. The cycle commences with the strongest beat during or immediately after the act of expiration, and the succeeding four or five beats are less and less forcible until the chest is fully expanded when there is a quiescent interval corresponding to the period of one beat. In many such cases there is no other indication of heart disease and the phenomenon appears due to the interference with the circulation by the hepatized lung, to the impaired nervous energy of the heart and to its compression between the distended lungs. A pulse simply _intermittent_ and not associated with any further sign of heart disease does not then possess the significance generally attributed to it, but a careful examination of the heart should invariably be made when this functional disorder is observed. It exists or may be brought about by slight excitement in the great majority of heart diseases.

In case of intermittent pulse it is useful to ascertain whether there is also an intermission of the heart’s beat, since in softening of the heart, that organ may beat without being able to transmit the impulse along the artery.

A pulse at once =unequal and irregular= is a much more serious indication than a merely intermittent pulse. It is observed especially in fatty degeneration of the muscular substance, and with imperfection of the valves on the left side of the organ, though it may be present in other cardiac diseases independent of the existence of those lesions.

In _hypertrophy of the left ventricle_, the pulse is full and strong and the impulse appears prolonged, because of the greater length of time taken up by the ventricle in the act of contraction. When _dilatation_ coexists with _hypertrophy_ the impulse is still full and strong, more blood being transmitted through the vessel; but when _dilatation_ is combined with _attenuation_ of the ventricular walls the impulse is soft and weak by reason of the feebleness of the contractions.

The pulse at the radial artery should be about synchronous with the beat of the heart. If retarded it may be held to indicate the existence on the anterior aorta or its primary divisions of an aneurism with elastic walls or more probably an imperfection of the aortic valves, which allows a regurgitation of the blood into the heart.

=Venous pulse.= A venous pulse seen in the lower end of the jugular veins is common in the domestic animals. In the ox it is quite compatible with health and is only to be judged by its amplitude and force. In other animals it often coexists with congestion of the lungs which impedes the circulation through the right side of the heart and leads to engorgement of the venous system. In the absence of this condition it frequently indicates an imperfection of the auriculo-ventricular valves in the right heart and a reflux of blood from the contracting ventricle which checks the descending current in the veins.

=Percussion.= In the =horse= a dull, dead sound is emitted when percussion is made over the left side for about four inches above the breast bone and in the space corresponding to the lower ends and the cartilages of prolongation of the fourth, fifth and sixth ribs. In the ox this dulness is less marked on the level of the sixth rib. The same results can be obtained on the right side by imparting heavier blows to the chest walls so as to derive the sound from the deeper parts.

The area of dulness is _increased_ in cases of _hypertrophy_ or in _dilatation_ of the heart when the enlarged organ presses aside the lung tissue and exposes a greater amount of its substance to the chest walls. The same result takes place in hydropericardium.

The area of dullness is _diminished_ in cases of ruptured air cells (as in “heaves”) when the inflated and expanded lung tissue envelopes the heart more completely and gives out its own clear resonance where the dull sound of the heart is usually obtained.

=Application of the hand.= =Palpation.= In conditions of health and in quietude the hand applied on the side of the chest, close behind the left elbow only just perceives the beat of the heart with each contraction. If the animal is excited whether from fear, joy or physical suffering the heart’s impulse becomes more powerful and by this alone the state of its function may be very satisfactorily ascertained. The impulse is strong in all active fevers and extensive inflammations of important organs, but it is especially marked in diseases of the heart and lungs. Irregularity in the force of successive beats is seen in various heart diseases and debilitated conditions are recognized in the same way.

Any want of harmony between the heart’s action and the pulse may be observed by laying the right hand over the region of the heart and applying the fingers of the left on the radial artery. In debility and especially if from a deficiency of blood the violent or tumultuous action of the heart contrasts strangely with the weak jerking and compressible pulse. The same symptoms are noticed when the valves of the heart close their orifices imperfectly. In convalescence from lung diseases and in certain diseases of the heart a beat may be felt by the right hand for which no corresponding pulsation is felt in the radial artery by the left.

When the heart is hypertrophied the impulse is stronger and is associated with a full, strong, and rolling pulse. When it is atrophied the impulse on the chest and pulse beat are equally weak. When water exists in the pericardium the heart strikes the ribs with less force.

=Sounds of the Heart.= Synchronous with each beat of the heart two distinct sounds are heard, separated by a short interval, inappreciable to most ears, and followed by a period of silence. These sounds are distinct alike in character and duration. The _first sound_ is dull and prolonged; the _second_ is short and quick. Some idea of these sounds may be formed by the pronunciation of the two syllables, _lub_—_tip_, but an acquaintance with the sounds themselves is essential to a correct conception of them. The period of time occupied by the first sound is double that taken up by the second and in man and the smaller quadrupeds the subsequent period of silence is of equal duration with the second sound. Dividing the time belonging to one revolution of the heart into four equal periods the first two are taken up by the first sound, the third by the second sound and the fourth by the interval of silence. In the horse the silence is more prolonged, and occupies the entire latter half of the period of a revolution. The relations stand thus:—the first sound extends over two-sixths of the time, the second sound over one-sixth, and the silence over three-sixths.

The _first sound_, synchronous with the beat of the heart against the ribs corresponds also in point of time with the contraction of the ventricles, the closure and tension of the auriculo-ventricular valves and the rush of the blood into the great arteries. The second sound corresponds to the reflux of blood in the arteries and the closure of the valves between them and the heart. The period of silence represents the period of rest during which the heart is being filled from the veins.

In the horse, at rest, the first is the only sound that can be distinctly heard in many cases, but during the excitement of exercise, or in febrile conditions the second is sufficiently apparent and any deviation from the natural character is easily noted.

These sounds are most distinct over the lower end of the fifth and sixth ribs on the left side, but they may be heard distinctly behind the middle of the shoulder on either side when the corresponding limb is advanced. In birds they may be heard beneath the wings but above all and most clearly over the breastbone.

In =disease= these =sounds= may be heard in unusual situations, they may be altered in force duration or rythm, or they may be associated with other sounds or superseded by them.

The sounds may be heard in new situations, in displacements of the heart from tumors or effusions in the chest, structural changes in the lungs, pleuræ, or pericardium, aneurism of the aorta, etc., etc.

The heart sounds are clearly heard over any part of the chest when the lung tissue intervening between that part of the surface and the heart is solid (hepatized). They are heard distinctly behind the median part of the right shoulder, when liquid effusion into the left pleural sac has displaced the heart to the right; and when the right cavities of the heart are extensively dilated as exists so commonly in the advanced stages of “_heaves_.”

The =extent= over which the sounds may be heard is _increased_ when the lung surrounding the heart is solidified (hepatisation, splenisation, etc.), or when liquid effusion exists in the chest. A liquid but more especially a solid is a better conductor of sound than the spongy lung. Enlargement (hypertrophy) of the heart equally increases the area of sound. The _area_ of sound is lessened by atrophy of the heart, and by an emphysematous condition of the lungs by which the heart is more extensively covered and further separated from the walls of the chest.

The =force= or =intensity= of the heart sounds is increased in high fever, in acute inflammation, in increase of the muscular walls of the heart with enlargement of the internal cavities, in functional disturbance from fear or other exciting cause, and in palpitation. Often in a weak and bloodless patient the heart sounds can be clearly heard at several yards distance from the animal. The _intensity_ of the sounds is diminished in debility when not associated with palpitation, in atrophy of the muscular substance of the heart, in hypertrophy of the muscular tissue of the heart with diminution of its internal cavities, in _broken wind_ when the emphysematous lung more completely envelopes the heart, and in cases of extensive liquid effusion into the pericardium which prevents the apex of the heart from striking against the side of the chest.

The regular =rythm=, normally manifested by the two sounds and the silence, may be modified in the unequal irregular or intermittent contractions of the heart. Küssmaul’s paradoxical pulse is one in which the pulse is more frequent but less full during inspiration than expiration. Seen in weak heart, during recovery from chest diseases, in chronic pericarditis, and when fibrous bands encircle the root of the aorta. Bigeminal and trigeminal when two or three beats follow each other rapidly, and are separated from the preceding and succeeding beats by longer intervals. This occurs in disease of the mitral valve, and in other weak states of the heart. Fœtal heart rythm in which the pause is shortened and the two sounds of the heart are almost identical, is seen in the later stages of fevers, and in extreme dilation. A curious aberration of rythm is the _repetition_ of either the first or second sound. If of the first sound (anapestic bruit) each beat will be accompanied by three sounds the first two of which resemble the first sound of health. If the second sound is repeated (dactylic bruit, bruit de galop) the first sound only will be prolonged and the last two sharp and quick. The repetition of the last sound is probably due to impaired nervous supply which allows the completion of the contraction of the ventricle and the closure of the arterial (semilunar) valves sooner on one side than the other. If due to diminution of the arterial orifice which retarded the emptying of one of the ventricles, the first sound would probably be accompanied by a blowing murmur. If the auriculo-ventricular valves on one side were imperfect, allowing a reflux into the auricle and a more rapid emptying of the ventricle a blowing murmur would equally accompany the first sound. In either of these two last mentioned cases the murmur would mask or hide the first of two doubled sounds.

The repetition of the 1st sound is often due to dilatation of one ventricle, which in consequence is longer in reaching the same sensation of plenitude, and in receiving the stimulus to contraction.

=Morbid Sounds.= =Murmurs.= The distinct and superadded sounds heard in disease are usually designated murmurs. They originate in the interior of the heart (endocardial) or externally to the heart (pericardial). The =endocardial= sounds mostly arise from some abnormal conditions of the valves or orifices and consist in a blowing or rushing noise which usually accompanies or displaces one of the heart sounds, though it may precede or succeed these. The following table modified from that of Bartle and Roger presents at a glance the relations of these different sounds and their significance.

Blowing or Hissing Murmurs.

Blowing murmur before │Narrowing of the auriculo-ventricular orifice.
the first sound. │ Vegetations or coagula on the valves.

│Strongest toward the │
Blowing murmur with the│ base of the heart. │Narrowing of the aortic
first sound. │ Propagated along the │ opening.
│ great arteries. │
│Strongest toward the │Narrowing of the
│ apex of the heart. │ pulmonary artery or
│ Not propagated in the│ insufficiency of the
│ great arteries. │ auriculo-ventricular
│ │ valves.

│Double rushing sound │Insufficiency of the
Blowing murmur with the│ heard over the great │ arterial (semilunar)
second sound. │ arteries at each beat│ valves.
│ of the heart. │

│Double rushing sound in│
Blowing murmur after │ the arteries with │Aneurism (dilatation of
the second sound. │ each beat of the │ the great aorta.)
│ heart. │

From the table it will be seen that each orifice in the heart may become the seat of two perfectly distinct and independent murmurs; one due to constriction of the orifice in which case the sound is produced with the onward progress of the blood wave; and one due to dilatation of the orifice or insufficient closure of it by the valves, when the sound is due to a recoil or regurgitation of the blood. There is a further sound due to mere roughness of the valves in cases of disease when the sound will be with the normal current of blood, though a second or regurgitant hiss is often heard from the valves being at the same time insufficient to close the orifice. Another blowing murmur is usually heard over the heart and coincident with its first sound in the bloodless state (anæmia). This is not necessarily connected with any diseased condition of the heart itself.

The nature of these murmurs differs in special instances. They may resemble the soft whisper of the words _who_ or _awe_, of the double letter _ss_, or the single letter _r_, according as they are soft or hard and purring.

The =pericardial murmur=, caused by the rubbing of the dry roughened surface of the serous membrane covering the heart on the correspondingly dry rough surface of the same membrane, reflected on the investing sac, resembles that caused by passing the palm of the one hand over the other which lies on the ear. It is distinguished from the friction sound of pleurisy by its coinciding with the movements of the heart and not with those of respiration. It is usually heard alike during the sounds of the heart and during the period of silence or in other words during the movements of contraction and dilatation in that organ.

=General Symptoms of Heart disease.= In the acute inflammatory affections there are the signs of general constitutional disturbance attending similar affections in other organs. The decision as to the true nature of the disease must be arrived at from the special character of the pulse, heart sounds, etc. as already noticed.

In the chronic forms of the disease however a particular class of symptoms usually point towards the organ affected. In cattle, sheep and pigs raised only for slaughter, and as far as possible protected against active exertion, serious heart diseases may exist for a length of time without making themselves manifest by any prominent symptoms. Thus in cows, pins and other sharp pointed bodies swallowed with the food frequently make their way to the heart and lodge for a length of time in its vicinity without material derangement and when at last the animal dies a sudden death they are found transfixing the walls of that organ. In the horse or other animal subjected to exertion the symptoms are usually very patent.

When the heart is enlarged the pulse strong and the circulation full and free, apoplexies or hemorrhages especially on the brain or other soft organs where the resistance is least, are liable to occur. When on the other hand the circulation is weak from atrophy or fatty degeneration of the heart, or from insufficiency of the valves there is a tendency to coldness of the extremities, and to passive congestions with their consequences:—serous effusions, dropsies, and difficult breathing. The imperfect supply of blood to the muscles of the extremities sometimes brings about an unsteadiness of gait in the hind limbs when the animal is trotted for a short distance and sometimes cramps supervene.

Continued coldness of the limbs, and a filling or thickening first of the hind limbs then of the fore and lastly of the chest and belly and of the skin beneath their dependent parts are useful indications.

Shortness of breath and inability to proceed when trotted or galloped on hard ground or when walked up hill, the animal being in fair condition, without fever or cough, but subject to cold extremities and a venous pulse in the jugulars, almost certainly indicates insufficiency of the auriculo-ventricular valves on the right side of the heart.

Vertigo megrims or giddiness may be caused by heart disease. The horse without having sustained any pressure on the veins of the neck by the collar, and having had no previous symptom of brain disease suddenly reels in harness and perhaps falls. There are the cold and engorged limbs or a tendency to their engorgement as in the former case. The attacks recur, when the horse is put to the same exertion, and he proves utterly worthless. In such cases a careful examination of the pulse and heart sounds will complete the chain of evidence.

An almost constant feature of chronic heart disease is a condition of dulness, sluggishness, and in many cases, curiously enough, a tendency to lay on fat, so that although the patient is unfit to work, he appears to enjoy excellent general health to which a period is only put by sudden death.

Affections of the heart are primarily divisible into _functional_ and _structural_ disorders.

PALPITATIONS.

Convulsive contraction of the heart, functional or structural
diagnostic features of these. Significance of the functional disorder,
genera most liable. Treatment, quiet, heart tonic, digitalis, correct
other disorders.

These consist in a sudden violent and convulsive beating of the heart, not connected with any appreciable structural disease. They differ chiefly from the palpitations of organic disease of the heart in the absence of any apparent local change to account for their occurrence. The following table from Bellingham furnishes a number of criteria equally valuable in the lower animals as in man.

PALPITATION DEPENDENT ON ORGANIC │PALPITATION INDEPENDENT OF ORGANIC
DISEASE OF THE HEART. │ DISEASE OF THE HEART.
│
1. Palpitation usually comes on │1. Palpitation usually sets in
slowly and gradually. │ suddenly.
2. Palpitation constant, though │2. Palpitation not constant, having
more marked at one period than at│ perfect intermissions.
another. │
3. Impulse of the heart usually │3. Impulse neither heaving nor
stronger than natural, sometimes │ prolonged; often abrupt knocking
remarkably increased heaving and │ and circumscribed, and
prolonged; at others irregular │ accompanied by a fluttering
and unequal. │ sensation (visible jerking or
│ lifting) in the precordial region
│ or epigastrium (flank and
│ abdomen).
4. Palpitation often accompanied by│4. Auscultatory signs of diseased
the auscultatory signs of │ valves absent; bellows sound
diseased valves. │ often present in the large
│ arteries and a continuous murmur
│ in the veins.
5. Rythm of the heart regular, │5. Rythm of heart usually regular,
irregular, or intermittent; its │ sometimes intermittent; its
action not necessarily quickened.│ action generally more rapid than
│ natural.
6. Mucous membranes often reddened │6. Mucous membranes generally pale;
and congested; dropsy of hind │ dropsy of hind limbs rare.
limbs common. │
7. Palpitation increased by │7. Palpitation increased by close
exercise, by stimulants and │ confinement; by local and general
tonics, etc.; relieved by rest │ bleedings, etc.; relieved by
and frequently also by local and │ moderate exercise and by
general bleeding and an │ stimulants and tonics,
antiphlogistic regimen. │ particularly the preparations of
│ iron.

Palpitations in the lower animals not dependent on any structural disease of the heart are usually due to some violent mental emotion, such as fear or joy. The author once possessed a fast and clever cob, having no sign of organic disease, and equal to the severest work on the road without showing signs of exhaustion, but which nevertheless was affected by palpitation when threatened with a cane in his stall, or if he had been guilty of some wilful misdemeanor for which he dreaded punishment. In such cases the heart’s action was accelerated and the beating could be heard loudly for a distance of several yards. They are especially common in dogs under strong mental emotion (joy, fear), and in dogs and pigs suffering from digestive disorder (worms) or chest diseases.

Percivall collects a series of cases from the _Veterinarian_ under the head of _Spasm of the Diaphragm_, a diagnosis originating in the jerking movement of the flank, a symptom which, as is shown in the above table, is common to man as well. Leblanc equally collects cases from the French veterinary journals and acknowledges their true character. One of these observed by Coulbeaux is thus described: “The respiratory movements are interrupted by a violent lifting of the flanks, confined to the upper part, and so intense as to be appreciated by the hand as well as the eye. The lifting of the flank which is limited to a few square inches of surface precisely in the hollow of this region, is perfectly isochronous with the beats of the heart, which cannot be appreciated but by the ear.”

A case reported by Levrat at greater length may also be given. The subject a mare, fifteen years old, and kept for hire, was attacked without any known cause. “There was a jerking of the whole body produced by the extraordinary force of the beats of the heart which struck violently against the back towards the upper ends of the first asternal ribs on the left side. The shock is very distinct and does not appear to be due to any tumor interposed between the heart and the ribs; its force is such that it causes a movement of the whole body, which can be seen at a great distance. The beats of the heart very regular, numbering fifty per minute, were heterochronous with the pulsations of the submaxillary artery, which are of the same number.” (The pulsation was evidently retarded). “The pulse was soft and regular. The breathing was peculiar. On approaching the ear to the nostrils the animal is heard to make three successive inspirations which coincide with the beats of the heart; each of these inspirations is followed by an expiration so short and feeble that the expired air can not be felt; the fourth is followed by full expiration sustained during three beats of the heart.” This form of respiration was continued without intermission for an entire day.

In three cases observed at the Lyons Veterinary School the disease continued for eight days. In all these and twenty more observed by Leblanc, the patients invariably recovered. The steady persistence of the disease for several days and the subsequent complete recovery under the unaided action of digitalis would seem to warrant the conclusion that such cases were really accompaniments of structural diseases of the heart and not mere functional disorders. Even inflammation of the lining membrane of the heart often exists without any obvious fever or other manifest symptom of illness, and in the dissecting rooms of medical schools nothing is more common than to find traces of pre-existing heart disease in patients whose whole life had been passed without the suspicion of such a malady.

A number of such cases observed in England and on the European Continent are adduced to prove spasm of the diaphragm or of the abdominal muscles, (Delafond), and great importance is attached to the fact that the convulsive movements of the abdomen and loins are heterochronous with the beats of the heart. This lack of exact coincidence however does not seem to amount to more than a perceptible delay after the heart beat, just as the maxillary pulsation is delayed in case of aneurism of the aorta. This has been my own experience with such cases. The flank movements have been equal in number to the heart beats or have corresponded to certain beats in the heart cycle, and have been perceptibly retarded in accordance with the necessity for time for the transmission of the blood wave along the posterior aorta and the development of the reflex action which set the phrenic and abdominal muscles in motion. We must of course accept the convulsive action of the phrenic and abdominal muscles, only it would seem that each such movement has its starting point in the contraction of the heart. In cases that show no relation in number nor succession with the heart beats, we can freely acknowledge a neurosis starting at a point different from the heart, but in all examples which are manifestly connected with heart movements, and readily curable by the heart-tonic digitalis, the recognition of the cardiac derangement as an initial factor is sound alike in pathology and practice.

Nervous and purely functional palpitations are probably confined to cases in which they are manifested at intervals appearing under the influence of some transient excitement, and continuing only for a few minutes at a time.

In the anæmic or bloodless condition the palpitation of weakness is often observed under the slightest exciting cause. It is then associated with a pallid state of the visible mucous membranes, a weak, trickling pulse and a blowing murmur in the larger veins.

Palpitations are much more frequent in pigs and dogs than in horses.

_Treatment._ Quietness and avoidance of all excitement are first to be secured, then the action of the heart is to be calmed and regulated by the use of digitalis. To the horse 15 to 30 grains of the powered leaves may be given thrice daily, and to the dog from two to four grains at equal intervals. When the disease is associated with anæmia this agent may still be used in combination with the various tonic remedies recommended, but in the smallest doses only as the heart is usually morbidly sensitive to external influences. Chloral hydrate has been used with success. Bromides, valerian, and belladonna may be tried in obstinate cases. Any other deviation from a healthy condition must be noted and corrected, especially any disordered condition of the stomach or bowels.

ANGINA PECTORIS. BREAST PANG.

W. Williams describes a case of illness in the horse to which he gives this name. When standing idle he had twitchings of the pectoral muscles, and when exercised these and adjacent muscles became violently convulsed, the left fore limb being alternately fixed by spasm, and paralyzed so that it was useless and the animal fell if compelled to move. There was “venous pulse, great irregularity of the heart’s action, a loud cooing or blowing sound and strong impulse indicative of hypertrophy and a want of correspondence between the cardiac energy and feeble pulse.” It was unfortunate that the murmur was not associated by the observer with a particular heart sound, and with the right or left side of the heart, and that hypertrophy was not diagnosed by percussion, since the case can be of little value as it stands.

Breast pang is usually associated with some disease of the heart: obstruction (usually calcification) of the coronary arteries, insufficiency of the aortic valves, calcareous degeneration of the aorta, aortic aneurism, or fatty degeneration of the heart. Loomis, basing his view on dissections made by himself and others, resolves all of these into concurrent ischæmia of the heart, the circulation in the coronary arteries being seriously interfered with.

“That the sudden withdrawal of a supply of blood to a part may occasion neuralgia is shown by the intense pain in the limb which directly follows embolism of the femoral artery. Moreover general anæmia, as is well known, favors the recurrence of neuralgia in various situations.” Inability of the heart to propel the blood is to be explained in the same way.

The difficulty of endorsing Williams’ diagnosis lies in the fact that the disease, so far as it is a distinct disease, is functional and manifested by pain, the nature of which can only be inferred in the case of the lower animals (not by spasms of the pectoral muscles), and that hypertrophy of the heart is not likely to be present in case of insufficiency of blood supply to its walls.

In true angina pectoris of the horse, treatment is useless. Absolute rest is a prime requisite, and anodynes, stimulants, heart tonics, and nerve tonics are indicated. But the horse at rest with no prospect of final recovery is simply a source of expense.

FUNCTIONAL IRREGULARITY IN THE RYTHM OF THE HEART.

Associated or not with palpitation, irregularity in the force or frequency of the heart beats is sometimes met with at intervals or independently of any further indication of structural disease. Particularly in the greyhound and certain other breeds of dogs the temporary occurrence of intermitting action of the heart is a frequent though a very transient condition. It may be excited by some emotion or excitement such as the attentions of the owner, or the straining anxiety in the immediate anticipation of the chase. Here again digitalis is pronounced the great panacea though it need not be resorted to unless the habit interferes with the usefulness of the animal. If in any degree dependent on weakness, that must be counteracted by a systematic tonic treatment.

CONGENITAL MALFORMATIONS AND DISPLACEMENTS OF THE HEART.

Ectopia Cordis. Cyanosis, pervious foramen ovale. Symptoms, blue
mucosæ, coldness, staring coat, unthriftiness. Unequal to exertion,
palpitations, murmur before the first heart sound. Obstructed
circulation in the lungs as a cause of cyanosis, cyanosis as a cause
of lung disease.

These have been much less frequently observed in the lower animals than in man. The anomalies observed in mammals include the following: The displacement of the heart to the right side of the chest; displacement entirely out of the chest (ectopia cordis); permanent communication between the right and left auricles (cyanosis); entire absence of heart; two hearts; one common ventricle communicating with two auricles as in reptiles; three ventricles; only one auricle; absence of one or several valves; absence of the pericardium; variations in the mode of connection of the heart and large vessels, etc.

=Displacements of the heart= have been especially studied by Hering on calves. The breast bone remained as originally developed in two lateral halves, and the heart remained outside connected with the interior of the chest only by its large vessels. The heart thus exposed and covered only by its investing membrane (pericardium) afforded an excellent opportunity to study its action, of which Hering freely availed himself. Animals affected in this way survived their birth but a very short time. An approach to this condition was thirty years ago made familiar to the medical world in the person of M. Gouz, a German mechanic, the movements of whose heart could be easily watched through a fissure in the breast bone.

=Permanent communication between the two auricles.= =Pervious foramen ovale.= =Cyanosis.= Previous to birth there is an opening between the right and left auricle, allowing the blood to flow from the former into the latter in place of, as in after life, descending into the right ventricle and thence circulating through the lungs. At birth this is contracted, and in a few days is completely closed in accordance with the new life, which demands that all blood must circulate through the lungs in order to its æration. Sometimes this fails to be effected, and venous blood from the right side of the heart continues to mix with arterial in the left, deteriorating it in quality and unfitting it for nutrition, secretion, calorification, and other essential processes. The semi-venous blood circulating in the arteries gives a bluish hue to the visible mucous membrane, hence the name of _the blue disease_. This blood is unfit for sustaining the vital changes essential to the production of animal heat, so that the animal suffers from coldness of the surface and extremities, staring coat and general unthrifty appearance. Such subjects grow badly, and refuse to lay on flesh, but are said to arrive at maturity in some instances and to have their imperfection recognized only because of the short breathing, and irregular heart’s action when subjected to exertion. A heart murmur preceding the first sound of health is usually present, as in anæmia.

Drs. Abernethy and Wardrop draw attention to the frequency of previous _foramen ovale_ in the human subject in connection with pulmonary consumption, and opine that it is reopened as a consequence of this disease. The coincidence has not been observed in the lower animals, though if it were found to exist the question would arise whether the deterioration of the blood and general health in open _foramen ovale_ did not also favor the deposit of tubercle in the lungs. When from deficient ventilation the atmosphere and blood become impregnated with carbonic dioxide the production of tubercle in man or in animals is correspondingly frequent.

The subjects of previous foramen ovale die young or prove worthless when they arrive at maturity. Nothing can be done to ameliorate the condition.

HYPERTROPHY OF THE HEART.

Simple, eccentric, concentric. Ventricles chiefly affected. Causes,
increased functional activity, from obstruction to the circulation, or
continued extra exertion. Right ventricular hypertrophy-obstruction in
the pulmonary circulation; left ventricular hypertrophy-obstruction in
the systemic. Auricular hypertrophy-insufficiency of the
auriculo-ventricular valves. Pericarditis as a cause. Abnormal
weights. Symptoms, beats more forcible and prolonged, 1st sound low,
prolonged, 2nd sound clear, often doubled, increased dulness on
percussion, diagnostic signs of hypertrophy, dilatation and a
combination of the two. Simple hypertrophy rarely dangerous, with
dilatation grave, threatens congestions and apoplexies. Treatment,
rest, laxatives, sedatives, in irregular heart action digitalis,
arsenic.

An enlargement of the heart from increase of its muscular substance is by no means uncommon in the horse. It may exist without any change in the capacity of the cavities of the heart (simple hypertrophy) or it may be associated with dilatation of one or more of these cavities (hypertrophy with dilatation;—eccentric hypertrophy). A third variety has been described in which the capacity of the cavities is decreased but Cruveilhier and Budd have satisfactorily shown the nonexistence of this condition except as a congenital deformity.

It is in the ventricles that the increase is chiefly observed, the reason of which is to be found in the causes of the malady. These usually consist in some obstruction to the circulation such as chronic congestions in the lungs or elsewhere, rupture of air cells in the lungs, tuberculous and other abnormal deposits in the chest and elsewhere, tumors which by their position interfere with the circulation through the larger vessels, and the like. Where by some such cause the blood is impeded in its outward course, one or both ventricles are called upon to contract more vigorously to force a sufficient amount of blood onward and in accordance with the inherent adaptability of the animal economy, there takes place an increase of the muscular walls of the ventricle proportionate to the required energy of the contractions. The condition then is essentially due to a more active nutrition and growth of the muscular substance and finds its exact parallels in the well-developed legs of the ballet dancer or the brawny arm of the blacksmith. All alike occur in accordance with a general law that whenever there is habitually demanded of any organ an unusual activity of function, which stimulates without exhausting its power, nature adds to the active element of such organ till the required labor can be accomplished without the overwork of any particular part.

Keeping this in view we can easily explain the increase of one part of the heart without immediate implication of another. The ventricles are more commonly enlarged than the auricles because upon them devolves the work of overcoming the obstruction, whether this exists in the lungs or the system at large. The auricles fulfill little more than a passive function in receiving the blood from the veins during the contraction of the ventricles and allowing it to pass down into these when their relaxation takes place. The closure of the auriculo-ventricular valves during the ventricular contraction protects the auricles from the internal tension to which the lower part of the heart is subjected and thus all tendency to increase is obviated.

The hypertrophied part corresponds to the locality of the obstruction. If it exists in the lungs (heaves, consumption, hepatisation, chronic bronchitis), pulmonary artery, its valves at its origin from the heart, or if it consists in contraction of that orifice, the enlargement takes place primarily in the right ventricle, the right auricle remaining unchanged so long as the auriculo-ventricular valves act perfectly. The ventricle, however, tends to dilate as well as enlarge in thickness of walls, and as soon as this dilatation has proceeded so far as to widen the orifice between the auricle and ventricle and render its valves insufficient, the auricle also begins to dilate and its walls often increase in thickness. But the vicious chain does not end here. Should the animal survive and the original obstruction persist, the veins throughout the system become habitually congested because of the reflux of blood from the right auricle and ventricle, dropsies appear in different parts, the congestion of the veins is continued through the capillary bloodvessels to the arteries, the difficulty of propelling the blood comes to be experienced by the left ventricle and a corresponding series of morbid changes taking place on that side, as have already ensued on the right, the vicious circle is soon completed, and the entire organ becomes diseased, each constituent part of the organ operating injuriously on that which preceded it in the track of the circulation, and every new change forming but a stepping stone to a more dangerous modification.

On the other hand the obstruction may exist in the general circulation, on the course of the aorta, or its branches, in its valves at its origin from the heart, or in the narrowing of its orifice. Then the increase takes place first in the left ventricle, is propagated to the left auricle, leads to congestion of the veins, capillaries and arteries of the lungs, and lastly to disease of the right side of the heart. Here there is a different starting point, but the progress of the disease-changes in a direction opposed to the course of the circulation is the same.

The disease may, however, begin with the auricles, owing to disease of the auriculo-ventricular valves impeding the flow of blood into the ventricle, or to simple narrowing of the auriculo-ventricular opening. The auricle is then primarily enlarged, the corresponding veins congested, this is propagated to the capillaries and arteries, and lastly the ventricle on the opposite side of the heart is involved. This is chiefly seen with fibrinous deposits on the valves or in the case of polypus hanging into the auriculo-ventricular opening. Aneurisms, embolisms, neoplasms, atheroma and calcic degeneration of the arterial walls may be effective factors.

In addition to these causes Bouilaud and Leblanc attach a high importance to chronic inflammations of the serous membranes, which by reason of the contiguity of the latter to the muscular structure bring about a more abundant circulation in this and an increased nutrition. Another cause is unintermitting hard work which necessitates excessive exertion of the heart, to supply blood more freely to the muscular system and the lungs. Many hunters suffer from this affection it is believed because of their extraordinary exertions. The stallion Helenus had a heart of 14 ℔s.

_Weight of the heart._ The heart in the horse which rarely weighs over 9 ℔s. is increased from 10 ℔s. to 14 ℔s. in this disease and in one case in a cart horse, recorded by Stephenson in the Veterinarian for 1861, it is said to have reached 32 ℔s. Stephenson probably weighed the heart while filled with blood. A diseased heart weighed in this way by Thomson amounted to 34 ℔s., one by Gerlach, 19 ℔s., an ox’s heart by Herran 36 ℔s. In Stephenson’s case there was further an extraordinary dilatation of the anterior vena cara. Haycock (Veterinarian, 1850), records a case in which though the heart only weighed 10 ℔s. 8 oz., yet the walls of the ventricles were double the normal thickness, those of the left being 2¼ inches while those of the right were 1 inch. An estimate from the thickness of the walls, it must be borne in mind, is not so satisfactory as the absolute weight taken after the removal of the large vessels, the superfluous fat and the contained blood.

The usual coincidence of other complaints supports the statement that it is mostly due to obstruction to the circulation. A few cases will illustrate. Dyer reports the case of a hunter in which with general hypertrophy and dilatation of the right auricle, the pulmonary artery was so large as to admit the fist. (Veterinarian, 1861). Halloway relates a case in which there were extensive internal deposits of melanotic material, especially in the mesenteric glands, liver, spleen, and kidneys (Veterinarian, 1850). Haycock records a case with thickening of the auriculo-ventricular valves on the right side, and of several of their tendinous cords, also a diseased liver which had ruptured before death (Veterinarian, 1850). Percivall publishes a case associated with pleurisy and rheumatism (Veterinarian, 1858). Henderson furnishes a case associated with diseased right auriculo-ventricular valves and enlarged liver weighing 55 ℔s. (Veterinarian, 1847.)

_Symptoms._ In simple hypertrophy the heart beats are more forcible and prolonged so that the period of silence or rest is shortened. This is due to the greater length of time taken up in the contraction of the ventricles. For the same reason the pulse which may or may not be accelerated, irregular or intermittent, is full and rolling or as it were prolonged. The first sound of the heart is prolonged and low or muffled, sometimes almost inaudible while the second is unnaturally loud. Sometimes when one ventricle only is enlarged that may complete its contraction later than the other and the second sound is repeated as in the syllables _lub_—_tip tip_. A duplication of the first sound only is less common. If the sounds are heard over a greater extent of the chest’s surface than is natural, the lungs being healthy, it is probably due to hypertrophy of the heart. If very clear on the right side they indicate increase of the right ventricle. The heart’s impulse is usually strong and may be felt on both sides, and it may be over the whole chest.

Percussion usually shows a more extended dulness in the region of the heart but the blows must be pretty forcible to bring out the deeper resonance, otherwise it will come only from the thin layer of lung. These results are of the greatest value in the dog.

The pulse is usually regular and if excited to irregularity and intermission quickly returns to its natural state when the patient is left at rest.

As hypertrophy is usually associated with dilatation of the heart the following table abridged and modified from Dr. Walshe will prove valuable by presenting side by side the signs indicating hypertrophy with and without dilatation, and simple dilatation.

TABLE CONTRASTING THE MAIN SYMPTOMS OF HYPERTROPHY AND DILATATION.

A. General Physical Signs.

SIMPLE HYPERTROPHY. HYPERTROPHY WITH SIMPLE DILATATION.
DILATATION.

Heart’s impulse slow Force increased, Impulse conveys a
and heaving as if sharper, more feeble undulatory
pressing steadily knocking, may impart sensation; force of
against an a shake to the body. successive beats
obstacle—in rythm May be felt on the unequal; rythm
regular, in force right side. irregular.
unequal.
First sound is dull, Sounds gain greatly in First sound short,
muffled, prolonged loudness and extent abrupt and clear.
and weakened almost of transmission, Second sound not
to extinction. Second especially if the specially affected.
sound full and valves are thickened.
clanging; period of
silence shortened.
Murmur with the first Murmur with the first Murmur with the first
sound present at one sound may be present, sound from
time and absent at from altered insufficiency of the
another. direction of the auriculo-ventricular
orifice of the aorta. valves.

B. General Functional Symptoms.

SIMPLE HYPERTROPHY. HYPERTROPHY WITH SIMPLE DILATATION.
DILATATION.

Strength unimpaired. Strength tends to Strength fails.
Power of continued become impaired.
exertion (especially
uphill) limited by
shortness of breath.
Visible mucous Purpleness and lividity Lividity of the mucous
membranes healthy or of the mucous membranes. Dropsical
of a bright red. membranes effusions of the
proportionate to the limbs and other
valvular or pulmonary dependent parts which
obstruction. pit on pressure.
Difficulty of breathing Difficulty of breathing Difficulty of breathing
occasional. occurs in paroxysms. great and constant,
with occasional
aggravations.
Pulse full, strong, Fulness of pulse Pulse small and feeble,
firm, tense, continues but much later than the
resisting and strength and power of heart beat. Regular
prolonged without resistance lost. or feeble, fluttering
jerk or thrill. and irregular. Venous
pulse in the
jugulars.
Rarely and never Indirectly and more or Palpitation frequent.
rapidly the direct less rapidly fatal. Faintness occurs from
cause of death. time to time, and may
lapse into fainting
and sudden death.

Pure hypertrophy rarely implies imminent danger unless dependent on some pre-existing structural disease which impedes the freedom of the circulation. If excessive, however, or if associated with dilatation the animal is short-winded and unfit for all but the slowest work. It predisposes to congestion or apoplexy of the lungs when its seat is the right ventricle, and to congestions and hemorrhage in other parts of the system, brain, kidney, lungs, liver, bowels, if in the left.

Asthma (dogs), heaves (horses), emphysema and tuberculosis in cattle are occasional complications attended by grave symptoms.

_Treatment._ In advanced cases and such as are dependent on irremovable structural changes in the lungs or elsewhere no treatment is of any avail. In recent and uncomplicated cases in the horse and cow and in some more advanced conditions in other animals, not used for work, a palliative treatment may be profitably adopted. This consists in a nitrogenous restricted and gently laxative diet, perfect rest in fattening oxen and other animals, or in the horse moderate and carefully regulated work, and as a medicament the use of digitalis or aconite. No known remedy has any power to directly check the growth of the heart and the utmost that can be expected of these agents is to lessen the activity of the heart’s action and retard its growth. Digitalis may be given as recommended for palpitation, or aconite in the form of tincture 20 drops for horses and cattle and 1 to 2 drops for dogs, repeated four times daily. Strophanthus may replace digitalis. When depletion seems advisable purgatives or diuretics should be given as appears most applicable to the particular case. Iodide of potassium has been strongly recommended.