Mosquito Season Is Coming: Heartworm Prevention for Dogs in North Carolina
Warm spring evenings in Raleigh are a gift: porch time, patio dinners, long walks after work. They also bring back an unwelcome guest, the mosquito.
For dogs, mosquitoes are more than itchy bites. They're how heartworm spreads. The good news is that heartworm disease is preventable. Here's a plain-language guide for Triangle pet parents.
What is heartworm disease?
Heartworm disease is caused by parasitic worms that live in the heart, lungs and nearby blood vessels of infected animals. According to the American Heartworm Society, the parasite spreads only through mosquito bites:
- A mosquito bites an infected animal and picks up tiny baby worms (larvae).
- The mosquito bites your dog and passes the larvae on.
- Over about six months, those larvae grow into adult worms.
That six-month timeline is important. A dog can be infected for months before anything looks wrong.
Why North Carolina dog owners should pay attention
The American Heartworm Society says heartworm has been found in all 50 states, and the risk is higher in some areas, including along the Atlantic and Gulf coasts and near rivers. North Carolina has both.
Add our long, warm, humid seasons, and the Triangle offers mosquitoes plenty of time to be active. If you've ever been eaten alive at a summer cookout here, you know.
Indoor dogs need protection too
This is one of the most common myths we hear. "My dog is mostly inside, so we're fine." The American Heartworm Society specifically notes that indoor pets are at risk too. Mosquitoes get indoors, and every dog goes outside for potty breaks.
"Think 12": the simple rule to remember
The American Heartworm Society sums up prevention with "Think 12":
- Test every 12 months. Your vet uses a simple blood test to check for heartworm.
- Give a preventive 12 months a year. Year-round prevention means no gaps.
Why test if your dog is already on a preventive? Doses get missed, a pill gets spit out behind the couch, or a topical gets washed off. The yearly test makes sure nothing slipped through.
A few more important facts
From the American Heartworm Society:
- Preventives require a prescription. Your vet will help you pick an option, given as a pill, a spot-on topical or an injection.
- There's no vaccine for heartworm.
- "Natural" heartworm remedies haven't been proven to work. Stick with what your vet prescribes.
- Early heartworm disease often has no signs. Later on, dogs may develop a mild, persistent cough, reluctance to exercise or tiredness after moderate activity. That's why testing matters.
Questions to ask your vet this spring
Bring this list to your next appointment:
- Is my dog due for a heartworm test?
- Which preventive fits my dog's age, size and health?
- Does the preventive also cover fleas, ticks or intestinal worms?
- What should I do if I miss a dose?
Make the monthly dose hard to forget
The Heartworm Society's point about missed doses is a good reminder that the best preventive is the one that actually gets given on time. A few simple habits help:
- Pick an easy date, like the first of the month, and set a repeating phone reminder.
- Mark the box or calendar each time you give a dose, so everyone in the house knows it's done.
- Keep the preventive with your dog's other supplies, not tucked away in a drawer.
- Plan around trips. If a dose falls while you're away, add it to your sitter notes ahead of time.
Easy ways to cut down on mosquitoes at home
Your vet's preventive is the real protection. Still, fewer mosquitoes around the house makes porch season more pleasant for everyone:
- Tip out standing water in buckets, flower pots, kiddie pools and clogged gutters.
- Refresh outdoor water bowls every day.
- Check your window and door screens for holes.
Please don't use human bug sprays on your dog unless your vet says a product is safe for dogs.
How we fit into the routine
We know how easy it is to lose track of monthly reminders. Every visit ends with a photo check-in and a report card in the app. The report card covers potty breaks, food, water and notes, so you always know how your pup is doing.
If you're traveling, our pet sitting visits keep your dog at home on their normal routine. Want to know what to look for in a sitter? Read what to look for in a pet sitter. For more springtime tips, see our spring hazards guide.
Frequently asked questions
How do dogs get heartworms?
Only through mosquito bites. A mosquito picks up larvae from an infected animal and passes them to a dog, where they mature into adult worms over about six months, per the American Heartworm Society.
Does my dog need heartworm prevention in winter?
The American Heartworm Society recommends giving a preventive 12 months a year and testing every 12 months. Talk with your vet about the right plan for your dog.
Can indoor dogs get heartworm?
Yes. The American Heartworm Society notes that indoor pets are at risk, because mosquitoes can get inside and dogs still go out for potty breaks.
What are the signs of heartworm disease in dogs?
Early on there may be no signs at all. As the disease progresses, dogs may cough, tire easily or avoid exercise. Annual testing catches infections that aren't visible yet.
Is there a heartworm vaccine?
No. Prevention comes from vet-prescribed preventives given on schedule.
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Sources
Sources were checked in October 2026. Local rules, hours and events can change, so please check the linked sources for updates.