List of five major heart diseases found in animals:- 1. Pericarditis 2. Myocarditis 3. Endocarditis 4. Aneurysm 5. Thrombosis.
Contents
Heart Disease # 1. Pericarditis:
It is of two kinds:
1. Idiopathic and
2. Traumatic.
1. Idiopathic Pericarditis:
Idiopathic pericarditis is not due to direct injury but through blood stream infection.
Idiopathic pericarditis may be noted in some forms of Septicaemia as well as in contagious diseases like Strangles, Influenza, Pneumonia, T. B. in horse; T. B., Rinderpest and contagious Bovine Pleuro-pneumonia in cattle; Distemper and Tuberculosis in dogs; Erysipelas and swine fever in pigs.
Symptoms:
Usually respirations are disturbed owing to the interference of oxidation by circulatory disturbance and pressure on the lungs by distended pericardium. Muscular twitching may be noted over chest and shoulder.
Left fore- limb may be carried forward. Jugular vein is distended or horse presents Jugular pulse. There is fever, temperature is raised and pulse is hard and frequent. On auscultation in the early stages, friction sounds may be heard in dry stage. In later stages, there is Oedema of the dependent parts.
On auscultation over heart, the presence of fluid is indicated by tinkling or splashing sounds. Frequently, heart sounds are muffled if there is much fluid. Light cases may recover in 2 or 3 weeks. Death may occur from Toxemia or Syncope due to pressure of exudate upon the heart. Acute form may be followed by chronic form or chronic forms may develop slowly without showing acute form.
2. Traumatic Pericarditis:
Traumatic pericarditis is most common in cattle in which the infection is carried to the pericardium by some foreign body such as piece of wire or nail from the reticulum. It may also be due to some external injury causing penetration into the pericardium.
Traumatic pericarditis is fairly common among cattle in certain areas. The foreign body responsible is usually a piece of nail or wire not more than 2 inches (5 cms.) long. The time taken for foreign body to enter the pericardium may be a few weeks or months.
Symptoms:
Are usually preceded by those Traumatic indigestion. Symptoms of Traumatic indigestion vary in intensity and may escape notice. It is only when the symptoms of pericarditis are set up that illness is observed. During the passing of foreign body through the diaphragm, there is tendency to fixation of the abdominal wall and respirations are thoracic. When the pericarditis proper appears, symptoms are identical to those in Idiopathic form.
In cattle, two forms of pericarditis most commonly seen are Traumatic and Tuberculous. An early symptom is distension of Jugular and Mammary veins. Frequently there is a grunt. In the later stages, Oedematous swellings appear in the sub-maxillary space and tinkling sounds may be heard over the heart.
This condition is almost always fatal from same cause as in Idiopathic form. Occasionally death is sudden from the penetration of the heart wall and rupture of the heart. Sometimes, the foreign body penetrates through intercostals space and forms a subcutaneous abscess which ruptures discharging the foreign body and the animal recovers.
Treatment:
It may be more economic to slaughter. In a few cases, this form has been dealt with by resection of ribs on the left side and removal of foreign body and fluid from pericardium. When fluid has accumulated, puncture pericardium on the left side in 4th or 5th intercostal space, 1 inch (2.5 cms.) above the point of elbow and remove fluid. Keep animal very quiet and in a comfortable well-ventilated room. Feed on easily digestible food, little but often.
Heart Disease # 2. Myocarditis:
Not common in a separate condition. It may be seen in combination with Pericarditis. Sometimes, it is due to infection of heart wall in abscess formation, in certain forms of pyemia (Joint ill in foals and lambs). A form of myocarditis may also be due to certain animal parasites, such as cysticercus cellulosae, bovis and ovis, Trichinella spiralis. The symptoms are not diagnostic and consists chiefly in irregularity of heart.
Treatment:
There is no cure.
Heart Disease # 3. Endocarditis:
Most commonly involves the valves. Often in those cases, thrombus formed on the side of the valves facing the blood stream. When the endocarditis involves the whole of inner wall of the heart, it is called Mural Endocarditis. Very sore and ulcerative form is described in which the thrombi forming from the valves break up and give rise to emboli. Later infarcts in kidney and other organs set up. When the lesions are chronic on the valves, they form wart-like growths such as Varicose endocarditis.
One may distinguish acute and chronic form. In most cases, the condition is due to some form of infection as it is seen in contagious diseases, e.g. in chronic form of Swine Erysipelas, in acute Rheumatism in Distemper, Strangles and Influenza. In Endocarditis not associated with contagious diseases, the organisms responsible are chiefly Streptococci, Staphylococci, Bacillus pyogenes and B-Coli and are brought to the heart in blood stream. Predisposing causes are cold, overexertion, accidents.
In dogs, a chronic form of Endocarditis with fibrous thickening and distortion of valves is commonly seen but the cause of it is seldom ascertained. It may be associated with Interstitial Nephritis. A form of Endocarditis in the dog is due to Filaria immitis in right ventricle.
Symptoms:
In the acute form, animal is not inclined to move, is languid, appears debilitated, respiration may be frequent or difficult. Fever occurs, veins may be distended and there may be Jugular pulse. Mucous membranes are cyanotic, pulse short, sharp and frequent. The heart sounds are often loud but may be irregular and intermittent. The course of acute form is usually short, may not be more than 2 to 3 weeks and is often fatal. If the animal survives, becomes chronic.
Chronic form:
Here the animal is unable to take severe exercise or do severe work. Respiration soon becomes disturbed and dyspnoea sets in. In dilatation of the right heart and in incompetence of right or tricuspid valve, a distension of Jugular vein or Jugular pulse is noted and there is a great tendency to dropsy. When there is incompetence of bicuspid or left valve, dyspnoea or coughing is sometimes noted due to passive congestion of the lungs. Pulse is small and drawn out in stenosis of aortic opening.
It is short and collapsing in incompetence of same valve. It is weak when there is dilatation of left ventricle but is unchanged when other parts of heart are involved. Occasionally it is irregular. The actual diagnosis of the affection is determined by auscultation. In Endocarditis, the valves are usually involved and, as a result, one or more become incompetent or the opening which they guard become stenosed.
On account of stenosis, an abnormal sound—viz. murmur—appears when the blood is passing through the opening in the normal direction, hence it is noted before the normal sound produced by the closing of valves. While in incompetence, the murmur is produced by the regurgitation of blood in the reverse direction owing to the imperfect closure of valves. This murmur occurs after the normal sound.
A systolic murmur is one occurring between Lub and Dub, results from incompetence of Auriculo-ventricular valves or stenosis of pulmonary or aortic openings. A diastolic murmur is usually due to either incompetence of semilunar valve or stenosis of auriculo- ventricular opening.
Chronic endocarditis may be followed by hypertrophy of the heart on the side of the lesion when muscular tone is good or dilatation when there is a want of tone as a result of extra pressure. Such animals are liable to sudden death during extra excitement or severe exercise.
Treatment:
Keep the animal at rest. Give laxative, light diet and keep the bowels open. Give heart tonics. In chronic forms, rest the animal and give very light exercise. Give food in small quantity. The treatment of chronic endocarditis is mainly palliative since it is impossible to restore the valves and orifice to the normal condition.
Purgatives should always be avoided on account of their production of general cardiac depression. Cardiac tonics should be used with discretion. In cases, where syncope threatens, hypodermic injection of Caffeine or atrophine may be administered. The sequence of cardiac insufficiency must also be treated as they arise. In cases associated with edema of cavities and tissues, diuretics may be added and drinking water curtailed.
Heart Disease # 4. Aneurysm:
An aneurysm is a local dilatation of an artery, generally brought about by weakened condition of the arterial wall, following up arteritis or degeneration. The commonest form of aneurysm is brought about by the Strongylus vulgaris in the horse. The larvae of this parasite are arrested in the vasa vasorum of the mesenteric artery and increasing its size there, produce the lesion of the intima and general weakening of the vessel wall which is followed by dilatation and thrombus formation. This condition sets up a violent verminous colic in horse.
Symptoms:
When the anterior mesenteric artery is involved, there is a sudden appearance of acute abdominal pain which increases in violence and may last for several hours. The animal knocks himself violently, rolls and struggles. There are frequent attempts at defecation and urination. The pulse is quick and hard and mucosa injected.
Respiration is blowing. The animal breaks out in patchy sweats. Death may occur in 4 to 12 hours in convulsions. Acute colic, however, may last for several hours and then develop into continuous subacute abdominal pain. This form is less likely to be fatal but may continue to produce symptoms for days or weeks.
Prognosis:
It is exceedingly difficult in either case. Death in verminous colic in acute cases may be due to direct interference with the circulation of the bowels, with the onset of gangrene and the absorption of toxins. In subacute cases, death usually results from enteritis which follows with the interference of the circulation and the passage of parasites into the intestinal wall.
Treatment:
There are no curative measures that can be applied to the relief of this condition and one must devote one’s effort to reduce the symptoms of pain.
Heart Disease # 5. Thrombosis:
Thrombosis is the name applied to the coagulation of blood within living vessels, whether in heart, veins or the arterioles. ,
Etiology:
The causes of thrombosis are:
1. Altered condition of the blood or increase in its coagubility.
2. Slowing of the current of blood within the vessels.
3. A lesion of the lining membrane of the vessel or cavity of the heart from contusion, stretching, wounding, infection etc.
Thrombi are more commonly met within vein than in arteries as these vessels possess thin walls which are more liable to injury and the circulation within them is more liable to become stagnant. Thrombi tend to shrink and so a vessel totally occluded may again become moderately useful with a small passage for the flow of blood.
Indeed, at a later stage, the whole thrombus may become absorbed provided that it has not been of large size. As a rule, however, calcification occurs with the production of phleboliths, or the thrombus may become organised and fibrous. Infected thrombi usually disintegrate and give rise to embolism or pyaemia.
Iliac Thrombosis:
Occurring in Iliac arteries or at their point of origin from the Posterior aorta, is by no means rare in horses. A similar condition is sometimes met with at the Bronchial artery and produces symptoms in the forelimb similar to those caused by the Iliac thrombosis in the hind ones. The vessel is at first only slightly obstructed, so that the onset of symptoms may be gradual.
At first, the occlusion of artery is only partial but it may become complete. As a rule, symptoms appear gradually, reach a maximum intensity and then becomes rather less severe but permanent as shrinkage occurs in thrombus. A thrombus once developed is seldom, if ever, absorbed, although portions may become detached and produce embolism lower down in the limb.
The causes of Iliac thrombosis are not very clearly understood at all. Possibly Strongylus is responsible in some cases. In fact, they have been found in the thrombi in postmortem examination in a few cases. Some veterinarians regard the condition as occurring as the result of changes in the endothelium arising from the presence of toxins of Influenza, Strangles.
Symptoms:
Are very characteristic. At rest, the animal shows nothing unusual and the thrombus is of small size, lameness may not be evident until the horse has been trotting for several minutes. Lameness may be more apparent while the limbs are being advanced or while at rest. In the former case, the thrombus usually lies in the femoral artery and causes deficiency of blood supply to the extensor muscles.
In the latter, the thrombus usually lies in the external iliac artery and cuts off blood supply to the gluteal muscles and to the quadriceps femoris. The leg is then unable to bear weight as all the lower articulation become flexed and then the symptoms resemble to those of crural paralysis—excepting that there is evidence of severe pain upon exercise and no disability on the part of the animal while at rest in the stable.
Sometimes the condition is bilateral and—in a few cases recorded—the thrombus has been capable of moving access the Aorta from one Iliac artery to the another. The lameness is accompanied by severe pain when exercise is forced. The animal sweats profusely whilst the affected limbs remain dry. The animal looks round anxiously at its hind quarter and, if forced to continue its pace, eventually falls to the ground.
Diagnosis:
Can be confirmed by rectal exploration and by lack of the pulsation in the arteries as compared to those of the opposite limb.
Treatment:
As the only hope of recovery lies in either the establishment of collateral circulation or absorption of the thrombus. Exercise must be continued daily until lameness appears and then cease, until the animal can again proceed without pain. Thiosinamine preparations may be given as a trial by intramuscular injection. Treatment is, however, almost invariably futile.