Your dog's heart is surrounded by a membrane called the pericardium. Normally, there's a small amount of fluid in this sac. When too much fluid builds up, however, pericardial effusion occurs. As this excess fluid presses on the heart, an emergency known as tamponade could develop. The heart of a dog experiencing tamponade can't pump sufficient amounts of blood, and dogs end up with right-sided heart failure.
Although any dog can develop pericardial disease, the condition occurs more often in certain breeds. Generally, giant and large breeds run the highest risk, with males affected more often than females. Pericardial disease rates are highest in golden retrievers, but Weimaraners, boxers and English bulldogs are also frequently affected. The disease usually strikes middle-aged to older canines.
Cancer is the primary cause of pericardial effusion in canines, with hemangiosarcoma, or cancer of the blood vessels, the main type of tumor. Congestive heart failure also causes pericardial effusion, as does an infection of the pericardium. Trauma to the heart or chest can cause fluid build-up. Idiopathic pericardial effusion means the cause is unknown. Your vet tests your dog's blood and urine and might take a sample of the fluid surrounding the pericardium to analyze for cancer or an infectious agent. She'll also perform X-rays, ultrasounds or an electrocardiogram.
The fluid accumulation connected with pericardial disease can come on suddenly, or acutely, but it's generally a chronic condition. Symptoms of pericardial disease mimic other types of heart problems. These include lethargy, lack of appetite, rapid breathing, pale gums, rapid heart rate and collapse. Dogs experiencing cardiac tamponade will display abdominal distention.
If your dog is suffering from cardiac tamponade, your vet will draw out the fluids via needle, a process that might require repeating. In severe cases, the pericardium can be removed surgically, as it's not essential to heart function. A dog's prognosis depends on the cause of pericardial disease. A canine diagnosed with a fast-spreading hemangiosarcoma might not live more than a few months because of the cancer, unrelated to pericardial disease. Other dogs might be completely cured once the fluid is drained or a pericardiectomy is performed.
By Jane Meggitt
About the Author
Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.