by Dr. Mikel Delgado, PhD and Dr. Nate Ritter, DVM

Unfortunately, heart disease is relatively common in dogs. It can be congenital (present from birth), or can arise later in a dog’s life. Congenital heart conditions can be inherited while  adult-onset heart disease occurs later in life and can be inherited or be due to “wear and tear.” Any dog can get heart disease, but some breeds appear to be predisposed to some conditions, suggesting genetic effects.

Heart disease sounds scary - and it can be. But when diagnosed early and managed, many dogs with heart disease can live a long and happy life! Screening, early and annually, is critical for ensuring a healthy breeding program especially for breeds at higher risk of developing heart disease. 

OFA Cardiac Evaluation Procedures for Breeders

The OFA maintains databases of Advanced and Basic Cardiac Evaluations to gather data regarding heart diseases in dogs, and to identify dogs who appear to be clinically normal prior to use in a breeding program. 

The Advanced Cardiac Evaluation screens for both congenital cardiac disease and adult-onset cardiac disease. The Advanced Cardiac Evaluation must be conducted by a licensed veterinary cardiologist, who will listen to your dog’s heart with a stethoscope (auscultation) and do an echocardiogram (ultrasound). 

The Basic Cardiac Evaluation screens dogs for cardiac disease and can be performed by any licensed veterinarian,  who will listen to your dog’s heart with a stethoscope. However, auscultation by board-certified cardiologist with specialized training is recommended. In either case, assessments of dogs under 12 months of age will be considered preliminary.

Signs of heart disease in dogs

How can you tell if your dog has heart disease? At your dog’s yearly check-up, your veterinarian will listen to your dog’s heart, assess other physical attributes, and let you know if they appreciate anything out of the ordinary. But heart disease can have a sudden onset. The most common symptoms to watch for include:

• Coughing: When the heart isn’t pumping efficiently, fluid can accumulate in the lungs and cause your dog to cough.
• Fainting: A weakened heart can lead to reduced blood flow to the brain. Exercise or coughing can lead to sudden collapse or fainting.
• Difficulty breathing: You may observe an increase in respiratory rate or effort. Your dog may seem uncomfortable.
• Fatigue: Your dog may tire out more easily from normal exercise or sleep more than normal.
• Restlessness: Your dog might have a hard time settling down or getting comfortable.
• Fluid retention in the belly: Fluid may accumulate in the abdomen, leading to a “potbelly” appearance.
• Changes in behavior: This sounds vague, but you know your dog and how they normally behave. If your dog suddenly loses interest in play or eating, that can be a warning sign that something is wrong.

How is heart disease diagnosed

The first step in assessing your dog’s heart health is through a basic physical exam, where your veterinarian can assess pulse quality, mucous membrane coloration, and jugular vein distention. Your veterinarian may be able to hear heart murmurs or other abnormalities during auscultation. These findings will guide further diagnostics, when potential issues are suspected or observed, in which case your dog may need additional testing such as:

• Chest x-rays: X-rays can measure the size of the heart and check for fluid build-up in the heart and lungs.
• ECG: An ECG monitors the heart for arrhythmias (irregular heartbeats). Your vet may have you place a Holter monitor on your dog to do 24-7 measurements of the heart patterns.
• Echocardiogram: An echocardiogram (sometimes just called an “echo”) is an ultrasound of the heart. It can measure several aspects of heart health and function, such as the shape, thickness of walls, and abnormalities or damage to various parts of the heart.

Additional diagnostics include checking your dog’s blood pressure and blood tests (e.g., NT-proBNP Blood Testing, heartworm testing). 

Some common types of heart disease

Mitral Valve Disease (MVD)

is one of the most commonly observed forms of heart disease in dogs, and is often the cause of a heart murmur. It can be congenital or acquired (adult-onset). Valves normally help blood to keep flowing through the heart in the right direction, but when the valves of the heart weaken, blood can leak back into the heart instead of out to the body. Over time, this can lead to congestive heart failure, where the heart cannot pump the right amount of blood into the body. Older dogs and some small breeds, such as Cavalier King Charles Spaniels, Yorkshire Terriers, Dachshunds and Miniature Poodles, are at increased risk for MVD.

Canine Dilated Cardiomyopathy (DCM)

is a condition where the muscles of the heart weaken, making it hard for the heart to produce enough pressure to pump blood. DCM can be genetic, or caused by infection or nutritional deficiencies. Some breeds predisposed to DCM include Boxers, Cocker Spaniels, and Great Danes.

Subaortic stenosis (SAS) and pulmonic stenosis (PS)

are heart defects related to the narrowing of the valves of the heart. SAS is related to the left side of the heart, at the aortic valve, and PS involves the opening of the pulmonary artery on the right side of the heart.  Both conditions obstruct blood flow in the heart and between the heart and the lungs, causing the heart to pump harder, eventually leading the chambers of the heart to thicken. SAS is heritable and a candidate genetic variant has been identified in Golden Retrievers, Rottweilers, and Newfoundlands. SAS is also observed in Boxers, Bouvier des Flandres, Bull Terriers, Bullmastiffs, German Shepherds, and Dogues de Bordeaux. PS is most often observed in brachycephalic dogs (e.g., Bulldogs, Boston terriers, Boxers), Jack Russell Terriers, Samoyeds, and Labrador Retrievers. 

Arrhythmias

are irregular rhythms in the heartbeat. Arrhythmias can be dangerous or they can sometimes lead to more serious heart problems. There are several types of heart arrhythmias, but some of them do have breed associations, such as the ventricular arrhythmia, which is found in German Shepherds, Boxers and Bulldogs.

Pericardial effusion

develops when the sac (pericardium) around the heart fills with fluid. Pericardial effusion is often an emergency. Dogs at risk of other heart problems may also be at higher risk of pericardial effusion, and breeds commonly affected include German Shepherds, Boxers, Golden Retrievers, Bulldogs, Boston Terriers, French Bulldogs, Afghan Hounds, Salukis, and Weimaraners.

Treatments for Canine Heart Disease

Most forms of heart disease are irreversible but can be treated and managed to give your dog a high quality of life. Treatments depend on the form of heart disease, and may include medication, dietary change, or even surgery. Some commonly used drug classes include ACE inhibitors, beta blockers and diuretics, which act in different ways to reduce stress on the heart and manage fluid accumulation around the lungs. The most important thing you can do is to work closely with your veterinarian, and if advised, with a licensed veterinary cardiologist to monitor your dog’s heart condition.

Preventing Heart Disease

There is no surefire way to prevent heart disease in dogs, but regular veterinary examinations and knowing what signs to look for will increase the chances of catching heart disease before it progresses. Early treatment often improves the prognosis. Keeping your dog in good physical condition is a great way to help their heart stay healthy. Nutrition is another important factor, as illustrated by the ongoing FDA investigation into a potential association between grain-free diets and development of DCM.

If your dog is a breed known to be at risk, talk to your veterinarian about what measures you can take to help your dog stay heart-healthy.

References/Resources

OFA Cardiac Database

Fear Free Certification Exams

What is a veterinary cardiologist?

Genetics of canine subvalvular aortic stenosis (SAS)