Heartworm Prevention 101: What Every Dog Owner Should Know
PetMedPal is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no extra cost to you. This never changes what you pay or our honest recommendations.
Heartworm disease is deadly but almost entirely preventable. Here's how monthly prevention works, what it costs, and how to never miss a dose.
What heartworm disease actually is
Heartworms are parasites spread by a single mosquito bite. Left unprevented, they mature in the heart and lungs and can be fatal — and treatment is far more expensive and grueling than prevention.
Prevention is simple
A monthly chew like Heartgard Plus interrupts the parasite's life cycle before it can mature. Most also treat common intestinal worms, giving you two-in-one protection.
Never miss a dose
Consistency is everything — set a monthly phone reminder or pair the dose with an easy anchor like the first of the month. Year-round dosing is recommended even in colder climates.
Tip: Heartworm preventives are prescription products. Our free discount card can reduce the price at participating pharmacies.
Save on your pet's meds
Grab our free Rx discount card — accepted at thousands of pharmacies.
Frequently asked
- Does my dog need a heartworm test first?
- Yes — vets test before starting prevention because giving a preventive to an already-infected dog can cause a dangerous reaction. Annual testing is recommended.
- Is year-round prevention really necessary in winter?
- Most veterinarians recommend it. Mosquitoes can survive indoors and in mild spells, and year-round dosing removes the risk of a forgotten restart in spring.