Tiring easily, a decrease in activity level and sporadic coughing when a dog is excited all can indicate the beginnings of congestive heart failure, according to WebMD. As the body becomes unable to compensate for the reduced function of the heart, the owner may observe a lack of appetite, rapid breathing, abdominal swelling and weight loss. In late stages, labored breathing, fainting and a rapid, irregular pulse may occur.
Many of the early warning signs of congestive heart failure can be caused by other ailments. Continued problems become more indicative of the disease. A backup of fluid in the lungs frequently causes coughing. When the fluid accumulates rapidly in the small airways, the dog may cough up a red fluid. This is indicative of failure of the left ventricle. When the fluid builds up in the abdomen, legs and chest cavity, failure of the right ventricle has occurred.
Some forms of heart disease are curable if treated before the heart is damaged. Heartworms, bacterial endocarditis and congenital heart disease are all treatable if identified early. A low-salt diet, restricted exercise and medications to improve heart function are all suggested treatments for congestive heart failure. Congestive heart failure is diagnosed using chest X-rays, blood and urine tests, an electrocardiogram or an ultrasound examination.