Congestive Heart Failure, Right-sided (Canine)
Canine congestive heart failure is a syndrome in which the right side of the heart cannot provide adequate blood flow to keep up with the needs of the rest of the body. It is a progressive disease and may be the end result of one or more of many different disease processes of the heart. Lifelong veterinary care is required.
Common name: Congestive heart failure
Scientific name: Canine congestive heart failure, right sided
There is no breed, sexual or age predilection for canine congestive heart failure specifically, but there are breed predilections for certain heart diseases that may lead to failure. Breed predilections for tricuspid valve dysplasia include the Labrador retriever, Great Dane, Golden Retriever and Weimaraner. Breed predilection for pulmonic stenosis includes the West Highland white terrier, beagle, boxer, basset hound, schnauzer, terrier breeds, English bulldog, Cocker Spaniel and others.
Since most heart disease is progressive, prevalence often increases with age. However, heart disease may occur in young animals, particularly those with congenital heart abnormalities.
There is no known geographic distribution for congestive heart failure, since there are many different disease processes and factors that may result in it. However, heartworm disease, which may lead to heart failure, is more prevalent in warm, humid climates where there are large mosquito populations (such as Florida and Louisiana).
Clinical signs (primary, most to least frequent, scientific term, synonyms)
Dyspnea (difficulty breathing), Tachypnea (increased respiratory rate), Weak pulses, Ascites (abdominal distension caused by excessive fluid in the abdomen), Weakness, Lethargy.
Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Subcutaneous edema (swelling under the skin caused by excess fluid), Jugular vein distension and pulsation, Hepatomegaly (enlarged liver), Splenomegal (enlarged spleen), Causes (scientific, common term), Valvular regurgitation (leaky heart valve).
Dilated cardiomyopathy (DCM), Doxorubicin toxicity (toxic dose of a type of chemotherapeutic agent), Dirofilaria immitis (heartworm disease), Pulmonic stenosis (area of constriction below the pulmonic valve), Pulmonary thromboembolism (blood clot in pulmonary arteries), Right atrial or ventricular mass (tumor on right side of heart), Pericardial effusion (excessive fluid surrounding the heart, inhibiting contraction), Arrhythmias (abnormal heart rhythms).
Organ systems affected (most to least affected)
Lungs, Liver, All organs may potentially be affected if they are not receiving adequate blood supply.
Thoracic radiographs, Electrocardiogram (ECG), Echocardiogram, Thoracocentesis, Abdominocentesis.
Other conditions that may cause increased respiratory rate and effort (such as primary lung diseases), Other conditions that may lead to abdominal distension (mass, peritonitis), Other conditions that may lead to weakness, weak pulses (hypovolemic shock).
Canine congestive heart failure is a syndrome in which the right side of the heart cannot provide adequate blood flow to keep up with the needs of the rest of the body. There are many different disease processes that may lead to heart failure. In the normal heart, the right side of the heart pumps blood coming from the veins of the body (this blood contains no oxygen) to the lungs. The blood picks up oxygen from the lungs, then goes to the left side of the heart, which then pumps the oxygenated blood to the rest of the body.
Congestive right-sided heart failure may be caused by any condition that impedes the blood flow returning from the body to the right side of the heart. Disease processes that lead to this may be classified into different categories: pump failure, volume overload, pressure overload, restricted ventricular filling and arrhythmias. Pump failure is the inability of the heart to contract and pump blood properly and is the result of dilated cardiomyopathy (DCM), doxorubicin toxicity and other diseases.
Volume overload can occur as a result of valvular diseases (such as tricuspid regurgitation) and leads to dilation of the heart chambers and subsequent thickening of the walls of the chambers. Pressure overload refers to an increase in ventricular pressure in the right side of the heart. The most common causes of pressure overload in the right side of the heart are pulmonic stenosis and heartworm disease. Finally, certain irregular heart rhythms may also lead to heart failure.
The disease processes that lead to heart failure may or may not have clinical signs. In early heart disease, the heart is often able to compensate for changes in volume and pressure. Congestive heart failure occurs when the heart is no longer able to compensate. Systemic congestion results from the impeded blood flow returning to the right heart from the body. Blood backs up, and fluid leaks through the vessels into other parts of the body. This may manifest as pleural effusion (fluid around the lungs), ascites (excessive fluid in the abdomen) and subcutaneous edema (fluid under the skin).
Stress should be kept to a minimum in a patient in congestive heart failure because it may exacerbate respiratory difficulty. Strenuous exercise and activity should be avoided so as not to make the heart work harder. Dogs should be monitored for increased respiratory rate or labored breathing, increased respiratory effort (may see the abdomen moving excessively with each breath), profound weakness or lethargy, and collapse. Cardiac medications prescribed by a veterinarian should be given as directed.
Any dog with the signs suggestive of cardiac disease should be seen by a veterinarian. Immediate treatment goals include addressing life-threatening conditions first. Fluid may need to be removed from the pleural space (area around the lungs) by thoracocentesis (with a needle) in order to help the dog expand its lungs properly and breathe better.
Patients that are not in congestive heart failure may have no clinical signs. A veterinarian may hear a heart murmur during a routine annual physical exam. However, not all patients with heart disease have a murmur or other signs detectable during physical exam.
A diagnostic and treatment plan should be developed by a veterinarian. The patient may be referred to a veterinary cardiologist for specialized care. Appropriate diagnostic tests may include thoracic radiographs (X-rays of the chest), electrocardiogram (ECG, rhythm analysis) and echocardiogram (ultrasound of the heart). Fluid accumulation may be controlled with diuretics such as furosemide. Other medications may be used to improve contractility of the heart (such as digoxin) or help reduce volume overload (enalapril, amlodipine). Special diets may be recommended.
Prognosis depends on the underlying cause of the disease and extent of permanent damage to the heart. Lifelong veterinary care is required.
Autran de Morais, Helio and Schwarz, Denise S. Pathophysiology of Heart Failure. In Ettinger, Stephen J. and Feldman, Edward C, eds. Textbook of Veterinary Internal Medicine. St. Louis: Saunders, 2005; 914-940.
Nelson, Richard W. and Conto, C. Guillermo. Management of Congestive Heart Failure. In Small Animal Internal Medicine. St. Louis: Mosby, 2003. 51-71.
Michelle Kazdin, VMD
Steven Hansen, DVM, MS, MBA, DABVT, DABT
© 2007. The American Society for the Prevention of Cruelty to Animals (ASPCA)