5 Canine Heart Problems to Know About
Heart disease is a relatively common condition in dogs, especially in older dogs. In fact, it is estimated that approximately 10 percent of dogs seen by primary care veterinarians have some form of heart disease [1]. There are multiple types of heart disease in dogs, each with their own unique causes and treatment. Read on to learn more about common canine heart problems.
What Causes Heart Problems in Dogs?
Heart disease in dogs, also known as cardiac disease, can have a number of potential causes.
Most canine heart disease is age-related. As dogs age, the valves within their heart may weaken and deteriorate. This prevents the heart valves from closing normally. Instead of blood flowing smoothly through the four chambers of the heart, a leaky heart valve can allow backflow within the heart, with some blood not moving forward along its normal path. Age-related valve degeneration is the most common cause of heart disease in dogs.
Some cases of heart disease are congenital, meaning the dog is born with a heart defect. This defect may be diagnosed at a puppy’s first veterinary exam, or it may be inapparent until later in life. Examples of congenital heart disease include patent ductus arteriosus (in which an embryonic heart vessel fails to close at birth), septal defects (presence of an abnormal opening that connects the left and right sides of the heart), and pulmonic stenosis (abnormally narrow pulmonic valve within the heart).
Less common causes of heart disease in dogs include viral infections, bacterial infections, tumors, nutritional deficiencies, hormonal disorders, and obesity.
Some breeds are more likely to develop heart disease than others. For example, Cavalier King Charles Spaniels almost always develop heart disease at some point during their lives. Other breeds that are predisposed to heart disease include Miniature Schnauzers, Toy Poodles, Chihuahuas, Shih Tzus, Boxers, and Doberman Pinschers.
Signs of Dog Heart Problems
Heart disease is often asymptomatic or nearly asymptomatic in their early stages. Your veterinarian may notice signs of heart disease on a physical exam, but these signs may not be obvious at home. Signs that your veterinarian may notice on their exam include:
- Heart murmur
- Abnormal heart rhythm (arrhythmia)
- Abnormal pulses
As heart disease progresses, you may start to see signs at home. Signs of heart problems in dogs may include:
- Coughing
- Increased respiratory rate
- Exercise intolerance
- Fainting
Congestive heart failure (CHF) is a late stage of heart disease. Dogs develop CHF when their body can no longer compensate for their heart disease. Signs of CHF include:
- Shortness of breath
- Difficulty breathing
- Cough (especially a productive cough)
- Blue tinge to gums
- Swollen belly due to fluid accumulation
- Weak pulse
- Lethargy
If your dog is showing signs of heart disease, schedule an appointment with your veterinarian. Your veterinarian will begin by performing a thorough physical exam, listening to your dog’s heart and lungs, palpating their pulses, and checking your dog carefully for other health issues.
If your dog’s exam suggests a possibility of heart disease, your veterinarian will likely recommend additional testing. These tests may include an electrocardiogram (ECG), chest X-rays, and/or an echocardiogram (ultrasound of the heart).
5 Canine Heart Problems to Know About
There are numerous forms of heart disease in dogs. Each type of heart disease is different in its underlying cause, its impact, and its treatment.
Here are five common heart diseases that affect dogs:
Mitral valve disease (MVD)
Mitral valve disease is the most common heart disease in dogs. The mitral valve separates the left atrium from the left ventricle of the heart. As dogs age, this valve can begin to deteriorate and become leaky over time. This means that blood isn’t pushed out of the heart normally when the heart beats; instead, some of the blood may leak from the ventricle back into the atrium. This forces the heart to work harder, leading to signs of heart disease.
While leaky mitral valves are typically repaired or replaced in people, this is not feasible in dogs. Therefore, MVD is managed, not cured. Your veterinarian will prescribe heart medications to support your dog’s heart function, as well as medications to prevent or treat the congestive heart failure that can occur secondary to mitral valve disease.
Congestive Heart Failure (CHF)
Congestive heart failure is a late-stage effect of any form of canine heart disease. When the heart cannot effectively move blood forward, fluid may begin to pool within the lungs and other parts of the body. This can lead to a variety of signs, such as difficulty breathing, a bloated or round appearance to the abdomen, and edema (fluid) in the legs.
The treatment of CHF involves removing this extra fluid from the body and the lungs. Veterinarians typically prescribe a diuretic, such as furosemide. More medications may also be prescribed to treat the underlying cause of CHF and otherwise support heart function.
Heartworm Disease
Heartworm disease is caused by a parasite, Dirofilaria immitis. This parasite is spread by mosquitoes. In fact, a single mosquito bite is all that it takes to spread heartworms to an unprotected dog.
Although heartworm larvae start off as small, microscopic parasites, they mature into large worms that look like spaghetti. These worms lodge within a dog’s heart and lungs, blocking normal circulation. Fortunately, heartworm infection can be prevented with the use of year-round heartworm preventative.
Dilated cardiomyopathy (DCM)
Dilated cardiomyopathy is a condition in which the heart muscle becomes weakened. This leads to enlargement of the heart, as the walls of the heart grow thinner and lose their normal shape. This condition is most common in large breed dogs, such as Great Danes, Boxers, and Doberman Pinschers. Diet can also play a role in the development of DCM, causing it to occur in breeds that are not commonly affected by this condition.
There is no cure for DCM. Instead, veterinarians prescribe medications to support heart function, reduce fluid buildup within the body, and reduce the risk of arrhythmias.
Pulmonic stenosis (PS)
Pulmonic stenosis is an inherited heart defect in which the valve between the right ventricle and the pulmonary artery (the vessel that carries blood to the lungs) is narrowed. This means that the heart must work harder to pump blood through this narrowed valve.
Pulmonic stenosis is treated with balloon valvuloplasty. This surgical treatment opens the valve up to a more normal width, restoring unobstructed blood flow.
Canine Heart Health: How to Stay Ahead of Problems
The most preventable cause of heart disease is heartworms. These parasites are spread by mosquitoes, and a single bite can be enough to cause life-threatening disease. Talk to your veterinarian and ensure that your dog is on year-round heartworm prevention to prevent heartworm disease.
Some cases of heart disease are nutritional in nature. Feeding an imbalanced diet can increase your dog’s risk of heart disease. Therefore, it’s important to talk to your veterinarian and ensure that you are feeding a nutritionally complete and balanced diet that’s appropriate for your dog’s life stage. If your dog is at increased risk of heart disease, or is already showing signs of heart disease, your veterinarian may recommend a cardiac diet or nutritional supplement.
If you are considering a purebred dog, do your homework. Some breeds are more likely to develop heart disease than others; avoiding these breeds can reduce your risk of adopting a dog with heart problems. If you’re purchasing a dog from a breeder, consult the Orthopedic Foundation for Animals’ recommended list of breed-specific screenings to determine whether cardiac screenings are recommended for that breed. Do not buy a puppy unless the breeder can verify that the puppy’s parents received and passed the recommended screening tests for their breed.
Unfortunately, most cases of heart disease cannot be avoided or prevented. Instead, it’s important to pay close attention to your dog and ensure that they receive regular veterinary care. Early diagnosis of heart disease allows early treatment, potentially improving your dog’s prognosis.
Reference
- Keene, Bruce W et al. “ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs.” Journal of veterinary internal medicine vol. 33,3 (2019): 1127-1140. doi:10.1111/jvim.15488
