05/29/2026
🐶🦟 HEARTWORMS ARE NOT THE SAME THING AS “WORMS.”
After 30+ years working around animals—vet clinics, shelters, rescue, transport—I am still absolutely amazed at how little people know about heartworm disease.
Every single week, we receive hundreds of messages asking for help with dogs.
And every single week, when I ask:
“Has the dog been tested for heartworms?”
I get some version of:
👉 “They’ve been dewormed.”
Y’all… those are NOT the same thing.
Let’s talk about it.
🦟 HOW DO DOGS GET HEARTWORMS?
Heartworms are spread by mosquitoes.
Not dirty yards.
Not bad owners.
Not other dogs.
A mosquito bites an infected dog, picks up microscopic baby heartworms, then bites another dog and deposits those larvae into that dog’s bloodstream.
One mosquito bite.
That’s all it takes.
🐾 WHAT HAPPENS NEXT?
Those tiny larvae travel through the dog’s body and eventually grow into worms that live in the heart, lungs, and major blood vessels.
Read that again.
HEART.
LUNGS.
BLOOD VESSELS.
These worms can grow up to 12 inches long and live for years.
💔 WHAT DO HEARTWORMS DO?
At first?
Usually nothing.
That’s one of the scariest parts.
Many heartworm-positive dogs look completely normal.
As the disease progresses, you may see:
▪️ Coughing
▪️ Exercise intolerance
▪️ Weight loss
▪️ Fatigue
▪️ Difficulty breathing
▪️ Heart damage
▪️ Lung damage
In severe cases, heartworm disease can be fatal.
🩺 HOW DO YOU KNOW IF A DOG HAS HEARTWORMS?
You test them.
That’s it.
You cannot look at a dog and know.
You cannot guess.
You cannot tell by their p**p.
A simple blood test is needed.
This is why rescues ask about heartworm tests on every dog over six months old.
💰 HOW MUCH DOES TREATMENT COST?
Treatment is expensive.
Very expensive.
Depending on location and veterinary clinic, treatment can easily run hundreds to thousands of dollars.
Treatment usually involves:
💉 Multiple injections
💊 Medications
🚫 Months of strict exercise restriction
And by strict, I mean STRICT.
A dog undergoing heartworm treatment cannot be running, playing, zooming, wrestling, or acting like a normal dog because increased heart rate can increase the risk of serious complications.
🛡 HOW DO YOU PREVENT HEARTWORMS?
This is the crazy part.
Prevention is MUCH cheaper than treatment.
Monthly heartworm prevention products can prevent heartworm disease before it starts.
Many products also help control other parasites at the same time.
Talk to your veterinarian about which product is best for your dog.
❤️ THE BIG TAKEAWAY
When a rescue asks:
“Has the dog been tested for heartworms?”
And you answer:
“They’ve been dewormed.”
That tells us you may not understand what heartworms actually are.
And that’s okay.
Nobody is born knowing this stuff.
But now you do.
A dewormer and heartworm prevention are not the same thing.
Heartworm disease is serious.
Heartworm treatment is expensive.
Heartworm prevention is simple.
If you own a dog, please make heartworm prevention part of your routine care.
Your dog—and every rescue trying to help dogs—will thank you.
📚 Want to learn more about heartworm disease, prevention, testing, treatment, and why it is such a serious issue?
American Heartworm Society — Heartworm Basics
https://www.heartwormsociety.org/pet-owner-resources/heartworm-basics
American Heartworm Society — Heartworm Prevention for Dogs
https://www.heartwormsociety.org/pet-owner-resources/heartworm-prevention-for-dogs
American Heartworm Society — Heartworm Disease in Dogs
https://www.heartwormsociety.org/heartworms-in-dogs
These resources explain:
🦟 How dogs get heartworms
❤️ What heartworms do to the heart and lungs
🩸 How heartworm disease is diagnosed
💉 What treatment involves
🛡 How prevention works
🐶 Why year-round prevention is recommended
The American Heartworm Society is considered one of the leading authorities on heartworm disease and prevention.
