The heart is responsible for supplying oxygen-rich blood to all organs in the body. In dogs affected by DCM, the heart muscle becomes stretched and thin, losing its normal strength and contractility. This results in a reduced cardiac output, meaning the body receives less oxygen and nutrients than it needs for normal function. Over time, this puts increasing strain on the heart and other organs.
DCM can be genetic (familial) in many dog breeds, while in other cases it may be associated with nutritional deficiencies, infections, toxins, or unknown causes. Large and giant breeds are most commonly affected, although some medium and small breeds can also develop the condition. Because of its hereditary component in many lines, cardiac screening is a critical part of responsible breeding programs.
Clinical signs of DCM often develop gradually and may not be obvious in the early stages. The first signs may include reduced energy, exercise intolerance, or mild fatigue after activity. As the condition progresses, more noticeable symptoms appear, such as coughing, rapid or labored breathing, and reluctance to exercise. Some dogs may also show abdominal swelling due to fluid accumulation (ascites) or fainting episodes caused by abnormal heart rhythms (arrhythmias).
In advanced stages, DCM can lead to congestive heart failure, where fluid builds up in the lungs (pulmonary edema) or body cavities, making breathing difficult and significantly reducing quality of life. Sudden cardiac death may also occur in some cases due to severe arrhythmias, even before severe outward symptoms are seen.
The DCM heart screening test typically involves a combination of diagnostic tools to evaluate both structure and function of the heart. The most important test is echocardiography (cardiac ultrasound), which allows direct visualization of the heart chambers, valve function, and pumping efficiency. This helps measure parameters such as left ventricular size and ejection fraction, which are key indicators of heart performance.
Additional diagnostic methods may include:
- Electrocardiography (ECG): to detect abnormal heart rhythms
- Chest radiography (X-rays): to assess heart size and detect fluid in the lungs
- Blood tests (including biomarkers like NT-proBNP or troponin): to evaluate cardiac stress or damage
- In selected cases, Holter monitoring for continuous heart rhythm assessment over 24 hours
Results of DCM screening are generally categorized based on heart size, function, and rhythm status:
- Normal: No evidence of chamber enlargement or impaired heart function
- Early/Preclinical Changes: Mild enlargement or subtle reduction in function without symptoms
- Moderate Disease: Clear structural and functional changes with or without mild clinical signs
- Advanced DCM: Significant heart enlargement, poor pumping ability, and signs of heart failure
DCM screening is extremely important for breeders, veterinarians, and dog owners. For breeders, regular cardiac evaluation helps reduce the risk of passing on inherited heart disease and supports healthier breeding decisions. For dogs already in breeding programs, annual heart checks are often recommended, especially in predisposed breeds.
For dog owners, early detection is crucial because timely treatment can significantly improve quality of life and slow disease progression. Although DCM cannot be fully cured, medical management—including medications to support heart function, control fluid retention, and regulate arrhythmias—can help extend survival and improve comfort.
The Dilated Cardiomyopathy (DCM) Health Test is a vital cardiac screening tool that supports early detection of heart disease, informed breeding decisions, and improved long-term heart health in dogs.
