What Causes Heart Disease in Dogs?

Heart disease in dogs can be caused by several different problems. The main causes include:

1. Genetics / breed predisposition: Some dogs are born more likely to develop heart problems. Certain breeds are prone to valve disease, heart muscle disease, or congenital heart defects. Congenital heart defects can be present from birth and may be linked to genetics, maternal illness, toxins, medication exposure, or poor nutrition during pregnancy.

2. Ageing: Older dogs commonly develop degenerative valve disease, especially mitral valve disease. This happens when the heart valves thicken or weaken and stop closing properly, causing blood to leak backward and making the heart work harder.

3. Heart muscle disease: Some dogs develop cardiomyopathy, where the heart muscle becomes enlarged, weak, or unable to pump blood properly. This is more common in some larger breeds, but it can occur in other dogs too. Merck Veterinary Manual lists heart muscle disease as one of the major abnormalities that can lead to heart disease.

4. Heartworm disease: Heartworm is caused by a parasite spread by mosquitoes. It can damage the blood vessels of the lungs and heart and may lead to heart failure if untreated. It is serious but preventable with veterinary-approved heartworm prevention.

5. Poor diet and obesity: Excess weight makes the heart work harder and can worsen breathing, blood pressure, inflammation, and overall cardiovascular strain. Diet alone is not the only cause of heart disease, but long-term poor nutrition and obesity can contribute to poor heart health.

6. High blood pressure: High blood pressure can put extra stress on the heart and blood vessels. It may happen alongside kidney disease, hormone disease, obesity, or other health problems.

7. Other health conditions: Chronic inflammation, kidney disease, thyroid issues, infections, tumors, anemia, and electrolyte imbalances can all affect heart function. Some dogs also develop rhythm problems, called arrhythmias.

Common warning signs include coughing, especially at night, fast or difficult breathing, fatigue, weakness, fainting, reduced appetite, swollen belly, and exercise intolerance. Cornell notes that difficulty or rapid breathing, coughing, weakness, lethargy, exercise intolerance, and collapse can be signs of heart disease, and a resting breathing rate above 35 breaths per minute should prompt veterinary advice.

Important Note: Always seek veterinary advice on poor health of your pet and keep them up to date with Heartworm preventitives and or treatment.