The word “Heart Failure” is scaring to a vast majority of peoples. It is the terminal event of heart diseases and is a complex progressive clinical syndrome of symptoms and signs caused by impairment of heart pumping action owing to structural and /or functional abnormalities. Though all species of animals have heart problems and some of these may lead to heart failure, it is of more concern in companion animals. India has around 20 million pet dogs and 2 million pet cats besides a vast number of stray animals

The heart failure is an important cause of morbidity and mortality in animals and man. It is the end stage complex event of cardio-vascular diseases. For having a better understanding of heart failure in animals for adopting rational therapeutic management, it is utmost necessary to have thorough knowledge about heart, its structures, its nerve supplies, its vasculature, current generation and conduction as well as its functioning in the healthy subjects.

Heart failure in canine is being recognized with an increasing frequency throughout the world. It is the end stage pathological event progressively occurring in heart diseases. Heart failure is the condition in which heart is unable to meet the metabolic and nutritional demands of the tissues of the body due to insufficient cardiac output. Heart failure has also been observed with normal cardiac output in conditions like hyperthyroidism or anemia where tissue metabolic needs are increased.

Oxygen therapy has been in vogue for more than century and it is key component in cardiorespiratory care both in human and veterinary medicine. It is recommended in all hypoxemic humans, dogs and cats (peripheral oxygen saturation < 90% to 94% or PaO2 < 70 mm Hg) presented with acute heart failure or respiratory diseases. But oxygen therapy in normoxemic subjects has remained controversial as some studies have shown detrimental effect (increased level of reactive oxygen species, oxidative stress, reduction in coronary blood flow and myocardial oxygen consumption) of oxygen therapy in subjects with normal oxygen level.

Anorexia in dogs with heart failure is very important clinical sign of concern as continued anorexia leads to weight loss and cardiac cachexia. Cardiac cachexia in dogs is the main reason that contributes to an owners’ decision to opt for euthanasia. It is therefore much more important to understand the various factors that lead to anorexia in dogs having heart failure. 

Diet plays an important role in the management of diseases. It is very much true in the management of dogs with heart failure also. Managing the diet of a dog with heart failure is depending on the severity and stage of heart failure and presence / absence of concurrent diseases as well deficiencies.

The word cardiac arrest (CA) or heart attack is frightening. In animals heart attack does not occur in the manner as it occurs in humans. In humans the main cause of cardiac arrest or heart attack is coronary infarct. The prevalence of cardiac arrest or cardiopulmonary arrest (CPA) or heart attack in animals is relatively very low as coronary infarct is not a common disease in animals.

Shock is a sequel to trauma or severe diseases such as heart failure, sepsis or acute inflammatory conditions like pancreatitis. Shock is generally associated with decreased supply and utilization of oxygen. The term shock is a chain of physiological events that can result in death if immediate rational treatment is not instituted.

Syncope can be aptly defined as sudden transient loss of consciousness and postural tone due to an abrupt cerebral hypoperfusion leading to a decreased availability of essential nutrients like glucose. Recovery from syncope is mostly spontaneous without any medical intervention. 

Pathogenesis of heart failure in animals and humans is a complex phenomenon. The major abnormality in heart failure is myocardial contractility failure, disturbances in rhythm and rate of the heart, disturbances of pre load and after load, forward failure, backward failure, fluid accumulation, RAAS activation, hypoperfusion of organs, oxidative stress, activation of proinflammatory cytokines etc.

Heart diseases in feline are silent killer as cats are able to hide their symptoms in early stage. Cats are brought to clinics only when disease is more advanced. Heart diseases are different from heart failure. Heart failure is the end stage of heart diseases.

Heart failure is the terminal outcome of heart diseases. It is defined as ventricular dysfunction (pump failure) leading to cardiac inability to maintain an adequate cardiac output. Heart failure is the outcome of filling defect, cardiac muscle abnormality, conduction defect, an excessive work load or a combination of these abnormalities.

Heart failure is not a disease but it is the end stage of heart diseases. Heart failure in horses is not very common as in dogs and cats. In horses it is characterized by the signs of forward failure, backward failure and fall in blood pressure.

With an increase in domestication of rabbits, a leporine, as pet in urban dwellings and their increased life span, risk of cardiac diseases has also increased. Heart diseases are being diagnosed in rabbits with an increasing frequency. The development of clinical signs of heart failure is gradual in rabbits causing late recognition of the heart disease.

Heart failure is the end stage of cardiac diseases. It occurs in pet birds when cardiac output is insufficient and unable to maintain arterial blood pressure. In birds right side heart failure is more common as compared to left heart failure.

The ferret is a domestic species of small mustelid. Congestive heart failure is most common form of heart disease seen in aged ferrets. Heart failure in ferrets is due to heart diseases and clinical presentation varies from no clinical signs in initial stage to many signs of fulminant heart failure.

Heart failure is a common progressive and complex clinical syndrome with high morbidity and mortality in humans. It is mostly due to cardiac involvement. Clinical signs and symptoms developed in heart failure cases are the manifestations of body’s compensatory efforts to meet chronic inadequate cardiac output as seen in other species of animals also.