The Four Stages of Heartworm Disease
Veterinarians classify heartworm disease in four stages:
Class 1 — Mild
No symptoms or an occasional cough.
Often only caught through annual testing.
Class 2 — Moderate
Occasional cough, tiredness after exercise.
Dog may seem "off" but functions normally.
Class 3 — Severe
Persistent cough, significant exercise intolerance, labored breathing, weight loss.
Signs of heart failure may be present.
Class 4 — Caval Syndrome
Life-threatening worm blockage.
Requires emergency surgical intervention.
The earlier heartworm disease is caught, the better the outcome. A dog in Class 1 treated promptly has an excellent prognosis. Class 4 is a fight for their life.
Sources: AVMA (American Veterinary Medical Association, Veterinary Partner, VCA Animal Hospitals , PetMD , American Animal Hospital Association, MedVet, PMC / NIH peer-reviewed research, Merck Veterinary Manual, VIN (Veterinary Information Network), Cornell University College of Veterinary Medicine, Sustainable Vet, American Heartworm Society (2024 Updated Canine Guidelines), the FDA, Companion Animal Parasite Council and trusted Veterinarians along my 17-year journey as a dog mom.
The Good Boy Foundation is committed to providing valuable resources and education to empower pet parents in caring for their furry companions. However, it's important to note that the information provided on our website is intended for educational purposes only and should never replace the advice or treatment provided by a licensed veterinarian. While we strive to offer accurate and helpful guidance, we cannot be held responsible for any outcomes or consequences resulting from the application of this information. Pet parents are encouraged to consult with their veterinarian for personalized guidance and recommendations tailored to their pet's specific needs and circumstances.