Pet CareUpdated: November 2025

How often should I give my dog heartworm medicine?

L

Loglast Editorial Team

4 min read

The Quick Answer

Give heartworm preventative medication once a month, every month, year-round. Even one missed dose can leave your dog vulnerable.

ItemFrequencySigns It Needs Attention
Dog Heartworm MedicineOnce a month, year-roundYou missed a monthly dose, You can't remember the last dose

Why Once a month, year-round? (The "Why It Matters")

Heartworms are transmitted by mosquitoes and can infect dogs in all 50 states. Treatment is risky, expensive ($1,000+), and requires months of restricted activity. Prevention costs about $10-15 per month.

Warning Signs You Waited Too Long

If you're noticing any of these signs, it's time to take action immediately:

  • You missed a monthly dose
  • You can't remember the last dose
  • Your dog has a persistent cough
  • Decreased appetite or weight loss

Pro Tips for Success

  • 1Give the medication on the same day each month
  • 2Set a phone reminder or use a tracking app
  • 3Many preventatives also protect against other parasites
  • 4Get annual heartworm tests even with prevention

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Frequently Asked Questions

What if I miss a heartworm dose?

Give the dose immediately when you remember, then continue the monthly schedule. If more than 2 months have passed, consult your vet.

Do indoor dogs need heartworm prevention?

Yes. Mosquitoes get indoors, and it only takes one bite to transmit heartworms.

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While You're At It...

Since you're thinking about dog heartworm medicine, you might also want to check:

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