The heart is a four chambered muscular organ that functions to pump blood around the body. Heart failure occurs when the heart fails to pump enough blood to meet the body's demands. This causes changes in the body as it tries to support a faltering system. These changes include increased blood pressure, increased heart rate and fluid retention.
Heart disease can have many origins. It can be caused by changes in the heart's muscular walls, defects of the valves separating the chambers of the heart or narrowing of the vessels leaving the heart. As with humans, heart abnormalities can exist at birth or can develop late in life and of course in pets, heartworm can be a contributing factor.
When the heart is unable to function correctly, there is a build up of fluid pressure within the circulatory system. This can cause "leakage" of fluid into the chest or abdomen and is responsible for many of the clinical signs seen with heart disease.
Clinical signs seen with Heart Disease:
- difficulty breathing
- engorgement of veins (often can be seen in the jugular vein in the neck)
- swollen abdomen (ascites - fluid in the abdominal cavity)
- enlarged liver
- weight loss
- decreased exercise tolerance - the dog tires easily
- pale or blueish mucous membranes
- cool extremities (toes, tips of ears etc)
- fluid swelling of lower limbs
If you suspect your pet is suffering heart disease, it is wise to have it examined by your veterinarian. Diagnosis of heart disease begins with a thorough physical examination. Listening to the patient's chest with a stethoscope can allow the veterinarian to identify any abnormal heart sounds, rhythms or lung sounds. If an abnormality is suspected, the next step is to x-ray the chest. Chest x-rays show the size and shape of the heart silhouette, any blood vessel enlargement within the chest and any changes in the lungs.
Some heart diseases can be diagnosed with the above, but there are other tests that can help further define the problems. Ultrasound of the heart (also called "echocardiography") is a technique that is very useful. It is used to see the size of the heart chambers, the degree of contraction of the heart and more advanced ultrasound machines can even show the direction of blood flow through the heart.
An ECG (electrocardiogram) is another way to investigate heart disease. This device records the electrical impulses across the heart as nerves fire to stimulate the heart to beat. ECG's are useful to determine any changes in the heart's rhythm and can give an indication of changes of heart chamber size.
Other tests such as blood and urine tests can help determine changes caused by heart disease and are often recommended before therapy for heart disease is started. Many different therapies for heart disease are available depending on the type and severity of the disorder. Most pets with mild heart disease respond well to therapy and can have an extended lifespan with treatment. Unfortunately, many heart conditions are progressive; this is why diagnosis of heart disease can be very important to give a more accurate prognosis. Therapy for heart disease is lifelong and generally requires regular rechecks to assess the stage of heart disease and any changes occurring.