Matters of the Heart
By Dr. Christina Britto
Max, an 11-year-old terrier, entered my office for evaluation of a three-month cough that he just couldn’t shake. His dad reported that Max seemed tired on his regular walks and was not finishing his favorite biscuits. His physical examination revealed a loud heart murmur and a crackling sound in his lungs.
SIGNS & CAUSES
X-rays of Max’s chest revealed that he had an enlarged heart with fluid in his lungs. Max was in congestive heart failure secondary to degenerative valve disease. Degenerative valve disease is the most common form of heart disease seen in dogs. It most commonly affects older, small breeds, like Mini Poodles, Cocker Spaniels, Mini Schnauzers and Dachshunds. Cavalier King Charles Spaniels are prone to the disease and can show symptoms much earlier in life.
The early symptoms of degenerative valve disease are vague, stressing the importance of yearly veterinary visits. Most symptoms seen in dogs are due to end-stage congestive heart failure. Like Max, dogs will have a cough due to fluid build up in their lungs or from compression of their windpipe by their enlarged heart. They tend to have decreased appetites, exercise intolerance, rapid breathing and even fainting episodes. Depending on which valve is affected, some dogs will get an enlarged abdomen indicating fluid build-up.
The heart is a very important organ responsible for pumping blood to and from all parts of the body. It consists of four chambers, with four different one-way valves to keep blood flowing. The right side of the heart pumps blood into the lungs to be oxygenated and the left side of the heart pumps oxygenated blood to the body. The valves open and shut with each beat of the heart.
Degenerative valve disease is where one or more of the valves between the chambers of the heart begin to degenerate. The most commonly affected valve is on the left side called the mitral valve, and the tricuspid valve on the right is sometimes involved. As a valve degenerates, it becomes thickened and nodular, which affects its ability to open and close efficiently. This constant leaking causes the heart to enlarge and dilate, leading to pooling of blood in the lungs and sometimes in the abdominal cavity.
DIAGNOSIS & TREATMENT
The first sign that your dog’s heart might be affected is when your veterinarian hears a heart murmur during his annual physical examination. A murmur is the noise heard when blood is flowing the wrong way through a valve in older dogs. Murmurs can also be heard in anemic or young dogs, and some sneaky dogs will have heart disease without a murmur.
Once a murmur is heard, several other diagnostic procedures will be recommended. X-rays will reveal if there is any heart enlargement or fluid build-up in the lungs. A proBNP blood test is a new test that can help your vet determine whether coughing is secondary to heart disease or lung disease. An electrocardiogram (EKG) test depicts whether the electrical system of the heart is performing normally and if there are any arrhythmias. An echocardiogram is an ultrasound of the heart that reveals what valves are affected and if there are any other structural abnormalities, like dilated chambers or thickening of the heart wall.
The findings from these tests determine what, if any, medications the patient will need. There are canine cardiologists who deal with heart disease extensively, so your veterinarian may recommend a consultation.
There is no reversing or slowing down the actual degeneration of the valves; however, we can ameliorate the signs of congestive heart failure with several classes of drugs. Diuretics, like Lasix, help remove fluid from the lungs and abdomen. Side effects can be increased thirst and urinating. ACE inhibitors, like Enalapril, dilate the vessels of the body making it easier for the heart to pump. Side effects can be intestinally related. A drug called Pimobendan slows down the heart rate and helps the heart pump stronger. Side effects are intestinally related also.
It is also important for your dog to maintain a healthy weight and participate in short, controlled exercise. A low-sodium diet can benefit dogs with heart disease, just like humans.
A common ailment amongst our smaller, older pets, degenerative valve disease progresses to congestive heart failure. The signs can initially be vague, and if undetected, heart disease can be fatal. Your veterinarian plays an important role in early detection and treatment of degenerative valve disease. With the appropriate medications and follow-up visits, dogs like Max can live comfortably for years.
Symptoms to Watch
» Exercise Intolerance
» Decreased Appetite
» Weight Loss
» Coughing
» Rapid Breathing
» Enlarged Abdomen
» Fainting
Dr. Christina Britto practices at the Brentwood Pet Clinic in West Los Angeles and has an interest in surgery and pediatrics. She shares her home with a mini Poodle named Sophie.
