Heart Disease in Dogs: A Practical Owner's Guide
Canine heart disease affects roughly 10 % of all dogs — and in some breeds, the prevalence is far higher. The field of veterinary cardiology has advanced enormously in the past two decades: dogs that would once have survived only months after diagnosis now frequently live years in good quality of life with appropriate treatment.
The Most Common Forms
- Myxomatous mitral valve disease (MMVD): degenerative mitral valve disease — the most common cardiac condition in dogs. Small and medium breeds, especially Cavalier King Charles Spaniels (near-universal by age 10), Dachshunds, Poodles, Chihuahuas.
- Dilated cardiomyopathy (DCM): the heart enlarges and loses pumping efficiency. Classic large breeds: Dobermanns, Great Danes, Boxers, Irish Wolfhounds. Also linked to taurine deficiency in some breeds.
- Arrhythmias: Boxer ARVC, inherited Labrador arrhythmia.
- Congenital defects: pulmonic stenosis, patent ductus arteriosus — typically picked up in young animals.
Warning Signs
- Chronic cough — especially at night, on rising, or after lying down (early pulmonary oedema sign)
- Exercise intolerance — tires much faster on familiar walks
- Rapid or laboured breathing at rest
- Swollen abdomen (ascites from right-sided heart failure)
- Syncope — brief collapse or fainting episodes, especially during or after exercise
- Weight loss and muscle wasting despite reasonable appetite (cardiac cachexia)
Diagnosis
- Auscultation: a heart murmur (grade 1–6) is the classic finding, but not all murmurs indicate disease, and not all cardiac disease produces a murmur early
- Chest radiograph: heart size, pulmonary oedema, pleural effusion
- Echocardiography: the definitive study — assesses valve function, chamber size, wall motion, pressures
- Biomarkers: NT-proBNP and cardiac troponin I — sensitive markers for cardiac stress and injury, useful for monitoring disease progression between echo visits
Treatment by Stage (ACVIM Classification)
- Stage A: breed predisposition, no disease — annual monitoring
- Stage B1: murmur, normal echo — no medication required; monitor every 12 months
- Stage B2: murmur + cardiac enlargement on echo → pimobendan has been proven in the EPIC study to significantly delay progression to heart failure
- Stage C: active heart failure → furosemide, pimobendan, ACE inhibitor (enalapril/benazepril)
- Stage D: refractory failure → dose adjustment, hospitalisation, additional agents
Log your dog's daily resting respiratory rate in Purzi. It's one of the most sensitive, free, at-home indicators of cardiac decompensation — far more useful than subjective impressions, and the kind of objective trend data your cardiologist actually wants.