Hypertrophic Cardiomyopathy in Dogs: 2025 Vet Guide 🩺🐶

By Dr. Duncan Houston BVSc

Hello, I’m Dr Duncan Houston, BVSc, veterinarian and founder of Ask A Vet. In this comprehensive 2025 guide, we review hypertrophic cardiomyopathy (HCM) in dogs—a rare but serious heart muscle disease. We'll cover its causes, echo diagnosis, treatment, prognosis, and modern telehealth tools to support your pup's cardiac health.

1. 🧬 What Is HCM?

HCM is a primary disease of the heart muscle that causes thickening (hypertrophy) of the left ventricular walls without an identifiable cause—hormonal, pressure-related, or systemic. This thickening reduces chamber size, impairing blood output during contraction (systole) and filling during relaxation (diastole), often progressing to congestive heart failure.

2. 🐕 Who Is Affected?

• HCM is very rare in dogs compared to cats.
• Often seen in young males < 3 years, especially Boston Terriers.
• The genetic cause remains uncertain, unlike in cats and humans.

3. 🩺 Clinical Signs

• Often asymptomatic—found via murmur or routine exam.
• If progressive: cough, difficulty breathing, exercise intolerance, weight loss, sudden fainting, or collapse.
• Physical exam may reveal a heart murmur, gallop sound, tachycardia, or cyanosis.

4. 📋 Diagnosis

1. Chest X-rays: May show enlarged left ventricle or pulmonary changes.
2. ECG: Often normal; may show ST/T wave changes.
3. Echocardiography: Diagnostic standard—reveals concentric LV thickening, papillary muscle enlargement, LA enlargement, and diastolic dysfunction.
4. Bloodwork: Generally unremarkable; rule out systemic disease.
5. Holter/EKG monitoring: For arrhythmias or syncope.
6. Phenocopy exclusion: Screen for metabolic or secondary causes.

5. 🛠 Treatment

Treatment is tailored to the disease stage:

• Pre-clinical/asymptomatic: Monitoring with periodic echo; no medications typically.
• Symptomatic or CHF present:
  • Diuretics (e.g., furosemide) to reduce fluid buildup.
  • ACE inhibitors (e.g., enalapril) to reduce cardiac workload.
  • Beta-blockers or calcium-channel blockers (e.g., atenolol, diltiazem) to improve diastolic relaxation.
  • Anti-arrhythmics if arrhythmias are detected.
  • Pimobendan may be used cautiously for systolic support.
• Obstructive HCM (rare): Beta-blockers first-line; consider surgical/myectomy only in referral settings.

6. 📈 Prognosis

• Generally poor in dogs with symptomatic disease; many deteriorate rapidly after CHF onset.
• One study of 68 dogs reported survival from 1 day to 114 months, median of 1.5 years.
• Early detection of asymptomatic cases may improve outcomes with timely support.

7. 🧡 Home & Telehealth Care (2025)

• Wearable echo/ECG patches—stream daily data via Ask A Vet.
• AI analysis—flag trend changes in LV thickness or rhythm.
• Symptom tracking—app logs breathing, activity, appetite, and cough.
• Reminders—med schedules, vet check-ups, echo rechecks.
• Virtual consults—review echo/arrhythmia results with specialists.

8. 🏠 Owner Care Tips

• Monitor breathing rate, activity level, and coughing daily.
• Report any syncope or episodes of collapse immediately.
• Schedule routine echo every 6–12 months or sooner if worsening.
• Administer medications diligently and log doses in the Ask A Vet app.
• Maintain moderate exercise levels—avoid stress or overexertion.

9. 🐶 Breed & Age Insights

• Most commonly seen in young dogs, especially Boston Terriers.
• Rare but documented in other breeds via case reports.
• Older dogs may develop LV thickening secondary to hypertension or hyperthyroidism—exclude those causes.

10. 💬 FAQs

Can dogs survive long with HCM? 

Asymptomatic dogs may live years; symptomatic dogs often deteriorate quickly without treatment. 

Will my dog need lifelong meds? 

Yes, likely for CHF or arrhythmia control. 

Is it genetic? 

Not clearly—genetic cause unknown in dogs, unlike feline or human HCM.

Should we avoid exercise? 

Keep activity moderate; stop if difficulty breathing or collapse arises.

11. ❤️ Role of Ask A Vet

With Ask A Vet, you receive:

• Continuous ECG/echo monitoring and alerts
• Medication scheduling and adherence support
• Remote specialist consultations for echo interpretation
• Symptom tracking and telehealth-guided care plans
• Connection to local cardiology for in-clinic diagnostics

Download our app to integrate home insights with expert oversight, keeping your pup’s heart resilient. 🐾❤️

12. 🔚 Summary

Hypertrophic cardiomyopathy in dogs is rare but can be life-threatening. Diagnosis relies on echocardiography, and treatment centers on supportive therapy for heart failure and arrhythmias. While prognosis is guarded, especially in symptomatic dogs, early detection and management—including digital health tools—provide the best chance for managing quality of life and longevity. Partner with your vet and Ask A Vet to champion your dog’s heart health every day.

— Dr Duncan Houston, BVSc