Congestive Heart Failure in Dogs

by: Laura McLain Madsen DVM

What is congestive heart failure in dogs?

Congestive heart failure in dogs (CHF) is not the same as a heart attack in people. In a heart attack in a person, a vessel which delivers blood to the heart muscle is blocked, depriving the muscle of oxygen it needs to pump. In congestive heart failure, the heart isn’t able to properly pump blood to the body and fluid backs up causing symptoms.

What are the symptoms of congestive heart failure?

Blood returning from the body is low in oxygen because the other organs and muscles have used it up. This blood enters the right side of the heart, which then pumps it to the lungs to pick up fresh oxygen. The oxygen-rich blood then enters the left side of the heart, which pumps it out to the rest of the body.

The symptoms of CHF in dogs depend on which side of the heart is affected, although often there are symptoms of both sides. If the left side of the heart fails to pump blood out to the body, fluid backs up into the lungs.

Fluid in the lungs can lead to coughing, difficulty breathing, rapid breathing rate, bluish gums, and standing with the elbows pushed out (to allow maximum expansion of the chest in breathing).

If the right side of the heart fails to pump blood to the lungs, fluid backs up into the rest of the body. Excess fluid in the tissues can cause swelling of the legs, liver problems, and fluid accumulation in the belly causing a distended abdomen.

General symptoms seen with either type of CHF are weakness, weight loss, loss of appetite, and decreased activity level.

Are certain breeds at risk?

Small-breed dogs, such as Chihuahuas, miniature poodles, miniature schnauzers, Cavalier King Charles spaniels, and Yorkshire terriers, are prone to a degeneration of the mitral valve in the heart. This valve is located in the left side of the heart and when it leaks the dogs can go into left-sided CHF, with coughing, difficulty breathing, and collapse.

Labrador retrievers are prone to an abnormality of the tricuspid valve in the right side of the heart. Leakage of this valve can lead to right-sided CHF with abdominal distension and weakness.

Dobermans are prone to a disorder called dilated cardiomyopathy (DCM), in which the heart muscle becomes stretched thin and can’t contract well. These dogs may show signs of both left- and right-sided CHF.

How is congestive heart failure in dogs diagnosed?

Your veterinarian will first perform a physical examination of your dog. In particular, he will listen to the heart and lungs with a stethoscope, checking for a heart murmur, irregular heart rhythm, and raspy or wheezy sounds in the lungs. He will also look at the color of the gums (pink is normal, while a lavender or blue indicates there is not enough oxygen going to the tissues) and the pulses (to assess strength and rhythm).

If your veterinarian is suspicious of CHF she will likely recommend several diagnostic tests:

* X-rays (radiographs) of the chest: to determine if the heart is enlarged, if there is fluid in the lungs, and to check for other disorders which could cause coughing (e.g., bronchitis, tumor, or collapsing trachea).

* Electrocardiogram (ECG or EKG): to determine the rhythm of the heart’s electrical activity.

* Echocardiogram: an ultrasound of the heart to determine if there is a leaky valve, measure the thickness of the walls, and quantify the heart’s ability to pump.

* Blood panel and urine analysis: to make sure there are no abnormalities of other organs, such as the liver or kidneys.

* Heartworm test: to test for heartworm, a parasite transmitted by mosquitoes which can cause heart disease.

What is the treatment of congestive heart failure in dogs?

Dogs in CHF are struggling to breathe so supplemental oxygen is helpful. Oxygen can be administered through a special air-tight cage, a mask that fits over the mouth and nose, or a small tube inserted into the nostril.

Various medications are used in treating CHF. Usually multiple medications will be necessary, because they act in different ways to help the dog. These include:

* Diuretics: furosemide (Lasix®), hydrochlorothiazide and spironolactone increase fluid excretion into the urine. This pulls the excess fluid out of the lungs and tissues, “drying up” the lungs so the dog can breathe more comfortably. Lasix® is really the mainstay for pulling fluid out of the lungs. It is usually safe, but will make dogs drink more and need to go outside to urinate more frequently. Other side effects are intestinal upset and loss of appetite. It can also affect electrolytes and kidney function, so most vets will recommend rechecking blood work a week after starting. Lasix® can be given by IV injection in the hospital or by mouth at home.

* ACE (angiotensin converting enzyme) inhibitors: enalapril (Enacard®, Vasotec®) and benazepril (Lotensin®, Fortekor®) are drugs which decrease the pressure that the heart needs to pump against, allowing it to pump more effectively. Side effects of both enalapril and benazepril are kidney problems, loss of appetite, and electrolyte abnormalities.

Vetmedin for Dog CHF Treatment* Pimobendan (Vetmedin®) helps the heart muscle contract more strongly, relaxes the blood vessels, and may have anti-inflammatory properties. Vetmedin® is newly licensed for use in dogs in the US and is favored by many veterinary cardiologists. It has been shown to lengthen the survival of dogs in CHF from mitral valve disease. Vomiting, diarrhea and lethargy are rare side effects. Vetmedin® should be given one hour before meals.

Most commonly, Lasix®, Vetmedin® and either enalapril or benazepril are used together. Other medications which may be needed on a case-by-case basis are:

* Blood pressure medications: if the dog has hypertension (elevated blood pressure), medications like amlodipine (Norvasc®) may be used.

* Vessel dilators: nitroglycerine and hydralazine dilate the blood vessels to decrease the “back flow” of fluid into the tissues.

* Anti-arrhythmics: if there is an arrhythmia (an abnormal heart rhythm), medications to stabilize the rhythm include atenolol, diltiazem, sotalol, mexilitine, propranolol and digoxin.

* Fish oil: the omega 3 fatty acids in fish oil have anti-inflammatory effects and are beneficial in heart disease.

* Diet: in general a high-quality dog food is fine, but avoid salty (high sodium) treats (deli meat, cheese, chips).

What is the prognosis and survival times?

The prognosis for congestive heart failure in dogs varies. If dogs are struggling to breathe they will usually be hospitalized until they are stabilized. Once the symptoms of fluid build-up are under control, the dogs can typically be discharged on long-term medications. CHF cannot be cured, but the symptoms can be managed. Once a dog has been diagnosed with CHF, he will need to be on oral medications for the rest of his life to prevent fluid build-up.

From the time of diagnosis, survival is typically from three months to two years for mitral valve disease. For Dobermans with DCM, the survival is less than six months, unfortunately.

How is congestive heart failure monitored?

If your dog is on long-term medications, the best way to monitor treatment at home is with the sleeping respiratory rate. When your dog is sleeping at home, watch the chest movements as he breathes and count the number of breaths per minute. It should be less than 30 breaths per minute. Check the sleeping respiratory rate a few times per week and record it in a log. If the sleeping respiratory rate is over 30, contact your veterinarian as the medication doses might need to be adjusted.

Can congestive heart failure be prevented?

Degeneration of the heart valves or muscles can’t be prevented, but can be detected early to allow prompt treatment. If a heart murmur or abnormal rhythm is detected on a routine physical examination, your veterinarian may recommend an echocardiogram or ECG to assess the heart. This won’t prevent the problem from progressing but will allow you and your vet to start treatment at the first sign of symptoms, before the dog is in a critical state.

Another thing you can do to reduce your dog’s risk is to make sure that he is on year-round heartworm preventative. Heartworm disease can be fatal but is easily prevented.

Although a diagnosis of congestive heart failure is serious, it is not an immediate death sentence. With proper treatment, dogs can have a good quality of life.

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