Canine congestive heart failure happens when your dog's heart is no longer able to pump blood to the rest of his body as efficiently as it ought. As your dog's heart weakens, the amount of blood entering the heart becomes greater than the amount of blood exiting the heart, and blood begins to leak from the blood vessels and build up in the chest cavity. As fluid accumulates in the chest cavity, it exerts pressure on your dog's heart, which further reduces the heart's ability to function and leads, eventually, to heart failure.
Understanding the Anatomy of Your Dog's Heart
Your dog's heart has four chambers, a left and right atrium (or pair of small upper chambers) and a left and right ventricle (or pair of lower chambers). The atrium and ventricle on the right are smaller, and they pump blood into the lungs at a low pressure. The atrium and ventricle on the left are larger and stronger; they receive oxygenated blood from the lungs and send it to the rest of the body. Each of the two ventricles has a valve that separates it from its companion atrium. When the valve is working properly, it prevents the backward flow of blood through the heart, as do the valves that separate the ventricles from the blood vessels that carry blood into and out of the heart.
Common Causes of Dog Congestive Heart Failure
There are two common cause of congestive heart failure in dogs: degenerative valvular disease (DVD) and dilated cardiomyopathy (DCM).
Degenerative valvular disease reduces the ability of your dog's heart to keep blood from flowing backwards through the ventricular valves when the heart muscles contract. The mitral valve between the left atrium and the left ventricle is usually the faulty one; vets call this condition mitral valve disease and they don't yet know what causes it.
Dilated cardiomyopathy occurs when the chamber of a ventricle gradually becomes larger, weakening it so that it can't pump blood efficiently. As the ventricle gets weaker, less blood leaves the heart, and congestion eventually occurs.
Mitral valve disease is common in geriatric dogs who belong to smaller breeds. Dilated cardiomyopathy is common in adult dogs who belong to large breeds like the Great Dane or Irish Wolfhound.
Symptoms of Canine Congestive Heart Failure
Regardless of the cause of your dog's congestive heart failure, the symptoms will always be the same. The symptoms of canine congestive heart failure usually get worse with time, as the disease is progressive. They include:
- Decreased appetite
- Fainting
- Difficulty sleeping, especially on one side
- Abdominal swelling due to a build up of fluid
- Lowered energy levels
- Coughing
- Drowsiness
Diagnosis and Treatment of Canine Congestive Heart Failure
Your vet will base his diagnosis on observation of physical symptoms and may ask questions about your dog's behavior. He'll listen to your dog's heart beat and may take chest X-rays and EKGs. He may perform a blood test.
Your vet will prescribe medication that can increase the amount of fluids your dog excretes, dilate the blood vessels and strengthen your dog's heart beat, and suppress any coughing. Your vet will restrict your dog's sodium intake. If your dog responds well to treatment, he could live for over a year after diagnosis.