How Common Is Heart Disease in Dogs?
Cardiovascular disease is one of the most prevalent conditions in companion dogs. Estimates suggest that between 10% and 15% of all dogs seen in general veterinary practice have some form of heart disease, and this proportion rises sharply in older animals and in certain predisposed breeds. The two most significant forms are myxomatous mitral valve disease (MVD) and dilated cardiomyopathy (DCM).
Myxomatous Mitral Valve Disease (MVD)
MVD is the most common cardiac condition in dogs, accounting for approximately 75% of all canine heart disease cases. It involves progressive thickening and degeneration of the mitral valve leaflets, leading to valve incompetence and regurgitation of blood back into the left atrium with each heartbeat. Over time, the extra volume of work placed on the heart causes it to enlarge and eventually fail to compensate, resulting in congestive heart failure (CHF).
Small to medium-sized breeds are disproportionately affected, with the Cavalier King Charles Spaniel showing such a high prevalence that MVD is essentially considered endemic to the breed. Dachshunds, Miniature Poodles, Chihuahuas, and Shih Tzus are also commonly affected. In large-breed dogs, DCM is the more typical presentation.
Dilated Cardiomyopathy (DCM)
DCM involves progressive weakening and dilation of the heart muscle, reducing the heart's ability to pump blood effectively. It most commonly affects large and giant breeds, including Dobermann Pinschers, Irish Wolfhounds, Great Danes, and Boxers. Dobermanns are particularly severely affected — many are in an advanced stage before any clinical signs become apparent, and sudden cardiac death may be the first indication of disease in some individuals.
In recent years, a possible nutritional link between certain grain-free or legume-heavy diets and DCM development in atypical breeds has been investigated, though research is ongoing and causality has not been definitively established.
Early Signs of Heart Disease
The early stages of heart disease are often clinically silent. A heart murmur — detected by your vet during a routine auscultation — may be the first indication. As the disease progresses, clinical signs begin to emerge.
- A persistent, soft cough — often worse at night or when the dog first lies down
- Exercise intolerance and tiring on shorter walks than usual
- Increased respiratory rate, particularly during rest or sleep
- Difficulty breathing or laboured respiration
- Abdominal distension due to ascites (fluid accumulation)
- Weakness, collapse, or fainting (syncope)
- Weight loss and muscle wasting in advanced disease
- Blue or grey tinge to the gums (cyanosis) — a serious emergency sign
Staging: The ACVIM and ECVIM-CA Classification
Heart disease in dogs is classified using a four-stage system developed by the American College of Veterinary Internal Medicine (ACVIM) and supported by ECVIM-CA guidelines. This staging system — derived from evidence generated by landmark trials including the EPIC trial and the QUEST study — guides treatment decisions at each stage of disease progression.
- Stage A: Dogs at high risk of developing heart disease (e.g., Cavaliers) but with no current cardiac abnormality. No treatment indicated; regular screening recommended.
- Stage B1: Heart disease present (e.g., a murmur) but no cardiac enlargement and no clinical signs. Currently no treatment is recommended at this stage.
- Stage B2: Heart disease with cardiac enlargement confirmed on radiography or echocardiography, but the dog remains asymptomatic. The EPIC trial demonstrated that initiating Vetmedin (pimobendan) at this pre-clinical stage significantly delays the onset of heart failure and extends survival time.
- Stage C: Current or previous congestive heart failure. Full medical management is required.
- Stage D: End-stage, refractory heart failure that does not respond adequately to standard treatment doses. Palliative management and quality-of-life discussions are central at this stage.
EU-Licensed Cardiac Medications
Several EU-licensed medications form the backbone of cardiac management in dogs. Their use is informed by robust clinical trial data and endorsed by ECVIM-CA and ACVIM consensus guidelines.
- Vetmedin (Pimobendan): An EU-licensed inodilator — a medication that simultaneously strengthens heart contractions and dilates blood vessels, reducing the workload on the heart. The EPIC trial showed that starting Vetmedin in asymptomatic Stage B2 dogs extended the median time to onset of heart failure by approximately 15 months compared to placebo. The QUEST study confirmed its superiority over benazepril in dogs with MVD-related heart failure. It is administered orally, ideally one hour before feeding, twice daily.
- Fortekor (Benazepril): An EU-licensed ACE inhibitor that reduces peripheral vascular resistance and decreases the volume and pressure load on the failing heart. Commonly added at Stage C alongside pimobendan and diuretic therapy.
- Frusemide (Furosemide): The diuretic of choice in dogs with congestive heart failure. It promotes excretion of excess sodium and water, reducing the fluid accumulation in the lungs (pulmonary oedema) or abdomen (ascites) that characterises decompensated heart failure. Dogs on frusemide require regular monitoring of kidney function and electrolytes.
Dietary Management: Royal Canin Cardiac
Nutritional support is an important component of cardiac management. Dogs with heart failure should be maintained at a lean body weight, as obesity increases cardiac workload. Sodium restriction is generally advised in Stage C and D disease to reduce fluid retention, though severe sodium restriction is no longer recommended as it can activate the renin-angiotensin-aldosterone system (RAAS) and worsen outcomes.
Royal Canin Veterinary Diet Cardiac is specifically formulated for dogs with cardiac disease, providing controlled sodium levels, taurine and carnitine supplementation to support myocardial function, and high-quality protein to counteract cardiac cachexia. It is available through Zooplus, making it straightforward for owners to maintain a consistent supply at home. Owners should consult their vet before switching to any prescription cardiac diet, as timing and suitability depend on disease stage.
Monitoring and Prognosis
Regular monitoring is essential for all cardiac patients. Chest radiographs, echocardiography, and blood pressure measurements are typically performed at three-to-six-month intervals. Owners can be taught to count resting respiratory rate at home — an increase above 30 breaths per minute during sleep is a reliable early warning sign of fluid accumulation and should prompt same-day veterinary contact. With appropriate treatment and monitoring, many dogs with heart disease live comfortably for years after diagnosis.