Heart disease is currently the leading cause of death in humans, causing about 600,000 deaths every year in the United States alone. But did you know that dogs and cats can also suffer from heart disease?
Although not nearly as common in pets as it is in people, heart disease is still a serious medical condition in dogs and cats. It can progress slowly and may take years to diagnose. Left untreated, heart disease leads to congestive heart failure, in which the heart is no longer able to effectively pump blood to the rest of the body.
When the heart can’t work effectively, blood begins to back up in the heart, lungs, and organs. Blood vessels constrict, pushing fluid out of the vessels and into other organs such as the lungs and liver. This excess fluid can accumulate in the chest and abdomen, causing a whole host of problems.
But before we go any further, first let’s start with a quick crash course in the heart itself.
The heart is a thick muscle made up of four distinct chambers: the right atrium, right ventricle, left ventricle, and left atrium. The leaflets of tissue separating each heart chamber are the heart valves. The purpose of these valves is to provide a one-way exit/entry point that keeps blood flowing in one direction.
When the heart contracts, each valve opens, and at the end of each contraction, the valve closes tightly shut to prevent blood from flowing backwards into the previous chamber.
Sometimes these valves malfunction and do not close properly. When this happens, blood leaks backwards, causing the heart to be less efficient and have to work harder. This turbulent blood flow makes a distinctive sound that is commonly referred to as a heart murmur.
The following audio clips were created by Dr. Steven Farmer, DO and shared by Rachel Sheppard of the My Kid Has Paws Blog. The first depicts a normal heart, while the second depicts a heart with Mitral Regurgitation Murmur, which is caused by a backflow of blood from the left ventricle to the left atrium (and is the most common heart condition in dogs).
This is what a normal heart sounds like:
Now listen to the Mitral Regurgitation Murmur:
During a normal heart contraction, the right and left atria contract simultaneously, forcing blood into the right and left ventricles. The ventricles then contract together to force blood back out of the heart and into the lungs and the rest of the body.
But what happens when everything doesn’t work the way it should?
Types of Heart Disease
Heart disease is classified into 2 types: Congenital and Acquired.
Congenital heart disease is caused by an abnormality in the developing fetus, and is already present at birth. Fortunately, these birth defects are relatively rare. Most congenital disease affects the heart valves. Some congenital conditions such as Patent Ductus Arteriosus (in which a blood vessel in the heart that is supposed to close after birth remains open), can be surgically repaired, but most cannot.
Acquired heart disease, on the other hand, develops over time and usually affects middle-aged dogs and cats. It can be caused by damage to the heart resulting from old age, infection (such as bacterial infections or heartworm), inherited genetic diseases, or diseases within the heart muscle itself.
The most common type of acquired heart disease in dogs is Chronic Valvular Disease (CVD). With CVD, the heart valves lose their ability to close effectively, leading to an abnormal blood flow within the heart. The second most common type is Dilated Cardiomyopathy (DCM), a disease of the heart muscle itself. With DCM, the muscular walls of the heart become weak and the heart chambers enlarge, leading to heart failure.
In cats, the most common type of acquired heart disease is Hypertrophic Cardiomyopathy (HCM), also a disease of the heart muscle. With HCM (which is usually inherited), the heart walls become abnormally thick, and the heart can no longer stretch and relax enough to sufficiently fill with blood. HCM can also affect normal heart rhythm in cats, bringing on sudden death. HCM can progress very rapidly, or over a period of several years.
Certain breeds of dogs and cats are more susceptible to inherited heart diseases. Cavalier King Charles Spaniels, Boston Terriers, Chihuahuas, Miniature Pinschers, Poodles, and Pomeranians are more likely to have higher incidences of mitral valve disease. DCM is more prevalent in Dobermans, Boxers, Great Danes, and Cocker Spaniels, while HCM in cats is seen more with Maine Coons, Persians, and British Shorthairs.
Symptoms of Heart Disease
Heart disease can be notoriously difficult to diagnose, since signs are usually so mild at first. Cats in particular often don’t display any clinical signs until the disease is fairly advanced.
What are the Signs of Heart Disease in Dogs?
Early symptoms of heart disease in dogs may include:
- Coughing (during or after exercise, at bedtime, or upon waking in the morning)
- Tiring easily
- Weight loss
- Difficulty breathing while exercising or at rest
- Restless pacing before bedtime; having a hard time settling down
- A racing heart rate at rest
- Abdominal swelling
- Blue or bluish-gray color of the tongue and/or gums due to decreased oxygen flow
Signs of heart FAILURE in dogs may include:
- Fainting due to blocked blood flow to the brain
- Weakness leading to collapse
- Irregular and rapid breathing
- Refusal to eat
- Edema (fluid retention throughout the entire body, including the legs)
What are the Signs of Heart Disease in Cats?
Unlike dogs, cats with heart disease rarely cough. Cats can exhibit exercise intolerance, but because they are normally less active than dogs, it may go unnoticed. Cats with heart disease tend to become more withdrawn, hiding under furniture and sleeping more.
The most common signs of heart disease in cats are:
- Poor appetite or refusal to eat altogether
- Weight loss
- Hiding in locations they don’t usually frequent (under furniture, in closets)
- Rapid, shallow breathing
- Sudden collapse
- Sudden paralysis of the back legs accompanied by pain
Diagnosis of Heart Disease
If you or your veterinarian suspect heart disease, your vet will perform a physical examination and recommend procedures that can properly evaluate your pet’s state of health. These may include chest x-rays, taking blood and urine samples, a heartworm antigen test to rule out the presence of heartworms, an EKG to measure the electrical signals within your pet’s heart, and an echocardiogram.
The echocardiogram remains one of the best tests available for evaluating heart disease. If you only elect to have one test performed, I recommend making it this one.
An echocardiogram is simply an ultrasound of the heart. It can be used to help diagnose a wide variety of heart abnormalities and provides a real-time view of the beating heart in amazing detail.
The echocardiogram not only enables the veterinarian to see if blood is flowing normally through all four chambers of the heart, but also whether the heart chamber dimensions are within normal limits. A diseased heart that has enlarged from having to work harder to pump blood throughout the body is easily identifiable on an echocardiogram.
Treatment for Heart Disease
If your dog or cat is diagnosed with heart disease, don’t despair. Although there is no cure for heart disease (with the exception of PDA, which can be surgically corrected), there are several treatment options that can help your pet enjoy a longer, better-quality life.
Success of treatment will depend on the age of your pet, the severity of the disease, and if there are any other illnesses present. Your veterinarian may develop a treatment plan, or he or she may refer you to a veterinary cardiology specialist with a wide range of experience in treating patients with heart disease or congestive heart failure.
Treatment may include:
- Medications to help take some of the load off the heart, correct irregular heartbeats, and slow fluid accumulation in the lungs.
- Limited activity or exercise to manage weight and reduce strain on your pet’s heart.
- Surgery by a veterinary surgery specialist to correct a congenital defect, or to insert a pacemaker to correct an irregular heartbeat.
- A prescription, low-salt diet to help decrease fluid buildup in your pet’s body and minimize cardiac problems.
- Supplements such as Vitamin B, Vitamin E, or taurine or carnitine (amino acids). The antioxidant Coenzyme Q10 has also shown promise for treatment of heart disease in dogs.
- A thorough education for you, as your pet’s caretaker, on how to carefully monitor the status of your pet’s health during treatment.
Can Heart Disease Be Prevented?
Although it’s not always possible to prevent heart disease in our pets, there are certainly things we can do to minimize risks to their heart health.
First, always keep your dog on a monthly heartworm preventative year-round. Heartworm disease can wreak havoc on your pet’s heart, but the good news is, it’s preventable! Cats are less likely to contract heartworm disease (you can read the reasons why in my post The Importance of Heartworm Testing and Prevention), but dogs are at high risk. There’s no reason not to protect them.
Pets, like people, also benefit from a healthy diet and regular exercise. Although the link between diet/exercise and heart disease is not as established in dogs and cats as it is in people, keeping your pet at a healthy weight takes strain off his heart (not to mention his liver, joints, and spine), and a healthy diet boosts his immune system. Letting your dog or cat become overweight will only cause trouble down the road if his heart health becomes compromised.
Regularly scheduled visits with your veterinarian are also important. Since early stages of heart disease often go undetected by pet parents, make sure your pet has an annual check-up so you stand the best chance of uncovering potential heart health issues before they become unmanageable. Early detection of heart disease provides the best chance for successful treatment.
If your pet is diagnosed with heart disease, remember that there are many treatment options available. If diagnosed early and managed correctly, in most cases your pet’s life can be extended through the use of various types of medications and supplements, as well as by feeding a prescription diet low in sodium.
Make sure to schedule regular visits with your veterinarian, and stick with your treatment plan.
Although heart disease cannot be cured, only managed, it is possible to extend your pet’s life with the right treatment, care, and monitoring. But most importantly, if heart disease is managed correctly, your beloved companion can continue to maintain a high-quality, happy, and comfortable life by your side for as long as possible.
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Have you ever treated a pet for heart disease? Any tips you’d like to share? Please tell us about them in the comments below!