Heartworms: A Serious Threat to Dogs
Heartworms are serious, potentially life-threatening parasites spread by mosquitoes. They live in the heart, lungs, and blood vessels of infected dogs, causing coughing, fatigue, and heart failure if untreated. The good news — heartworms are completely preventable with monthly medication.
How Dogs Get Heartworms
Heartworms are spread only by mosquitoes.
- When a mosquito bites an infected animal, it picks up microscopic larvae.
- Those larvae are passed to another dog during a bite and grow into adult worms inside the heart and lungs.
- The cycle takes about 6 months — so even indoor dogs can get infected if a mosquito gets inside.
Prevention Is Key
- Give a heartworm prevention every month, year-round — even in winter.
- Most monthly preventives also protect against intestinal parasites, making them a great all-around choice.
- Mark reminders on your calendar or set an alert on your phone so you never miss a dose.
Common preventives include:
- Chewables: Heartgard Plus, Interceptor, Sentinel, Simparica Trio, NexGard Plus
- Topicals or injections: Advantage Multi, ProHeart 6 or 12
Testing
- Dogs should be tested for heartworms once a year, even if they stay on prevention.
- Puppies start prevention as early as 8 weeks old, but should be tested around 6–7 months of age.
- If prevention is missed or late, your vet may recommend retesting sooner.
If Your Dog Tests Positive (4-6 months of treatment)
Heartworm treatment is safe and effective, but it takes time and strict rest. Your vet will use a series of medications to kill adult worms and larvae.
During treatment:
- Keep your dog quiet and calm — no running or rough play.
- Strict exercise restriction is vital to prevent complications.
- Follow all medication directions carefully.
After Treatment
- Continue monthly prevention to stop reinfection.
- Retesting will be done a few months after treatment to ensure your dog is clear.
- Regular yearly testing and prevention are the best protection.
Quick Facts
- Heartworm disease is 100% preventable.
- It only takes one missed dose to put your dog at risk.
- Mosquitoes are active year-round indoors — prevention never stops.
Protect your dog from heartworm disease — schedule a heartworm test and discuss year-round prevention with your veterinarian today