Heartworm Disease: What Every Dog Owner Should Know
Dog heartworm disease is something no pet owner wants to face—but the good news is, it’s easily preventable. It’s also critical for dog owners to be informed, as early detection and treatment can make all the difference.
At Whittington Veterinary Clinic, we’re here to provide accurate, dependable guidance to keep your dog healthy. We've put together answers to the most frequently asked questions about heartworm disease to help you stay informed and proactive. In South Louisiana, where mosquitos never really go away, year-round prevention is especially critical.
What is heartworm disease and how does it affect my dog?
Heartworm disease is a serious, potentially fatal condition caused by parasitic worms that live in the heart and lungs. They interfere with blood flow, damage the heart and pulmonary arteries, and can lead to coughing, breathing issues, and other organ problems. The disease is spread by infected mosquitos and is especially common in warm, humid areas like Louisiana.
How do dogs get heartworms?
Heartworms are spread through mosquito bites—nothing else. A mosquito picks up immature larvae from an infected dog, then transmits those larvae to the next dog it bites. In about 6 months, those larvae grow into adult worms that live in the heart and lungs. Because mosquitos are active nearly year-round in South Louisiana, the risk of heartworm infection never truly goes away.
Can heartworms be prevented?
Absolutely. Monthly preventatives—whether oral or injectable—kill heartworm larvae before they mature. Since mosquitos can’t be fully avoided in our region, prevention isn’t just recommended—it’s essential. Missing even one dose can put your dog at risk.
What are the symptoms of heartworm disease?
Early infections often have no symptoms, which is why annual testing is so important—even for dogs on prevention. As the disease progresses, symptoms may include:
- Coughing
- Fatigue or reluctance to exercise
- Difficulty breathing
- Weight loss or poor appetite
- Swollen belly or limbs (in severe cases)
Left untreated, heartworms can cause irreversible damage to the heart, lungs, and other organs.
How do we test for heartworms?
A quick blood test checks for proteins released by adult female heartworms. If a dog hasn’t been on prevention—or has missed doses—we may recommend testing again in six months to catch any developing infection.
Why is early detection so important?
Detecting heartworms before symptoms start allows for earlier, more effective treatment—and helps minimize long-term damage to your dog’s organs. The longer the infection is left untreated, the more complicated recovery becomes.
What’s involved in treatment?
Treating heartworm disease is much tougher than preventing it.
Treatment includes:
- A series of deep muscle injections to kill adult worms
- Steroids and medications to reduce inflammation
- Strict exercise restriction for several months
- Multiple visits to the clinic
This process can be hard on both your dog and your wallet, which is why prevention is always the better choice.
When should I start my dog on heartworm prevention?
As soon as possible. Puppies can start prevention at 6 to 8 weeks old. Dogs over 6 months should be tested before starting. If you’ve adopted a new dog or missed any prevention doses, we recommend scheduling a test and getting back on track right away.
Heartworm Disease: Common Myths
Myth #1: Indoor dogs don’t need heartworm prevention.
Fact: Mosquitos can easily get indoors. Even dogs that rarely go outside are still at risk and should be protected year-round.
Myth #2: You only need to give prevention during mosquito season.
Fact: In South Louisiana, mosquitos are active nearly all year. Skipping prevention even for a short time can leave your dog unprotected.
Myth #3: Heartworm disease isn’t serious.
Fact: Heartworms can cause permanent damage to the heart, lungs, and other organs—and the disease can be fatal if left untreated.
Myth #4: You’ll know right away if your dog has heartworms.
Fact: Most infected dogs show no signs until the disease is advanced. That’s why annual testing is essential—even for dogs on prevention.
Myth #5: You can skip the test if your dog is on prevention.
Fact: Testing is still recommended. No prevention is 100% effective, and missed or late doses happen. Annual screening ensures your dog stays safe.
At Whittington Veterinary Clinic, we offer two trusted options for heartworm prevention: ProHeart and Simparica Trio.
ProHeart is an injectable prevention that protects your dog for 6 or 12 months with a single dose—perfect for busy pet owners who want worry-free protection.
Simparica is a convenient monthly chewable that not only prevents heartworms but also protects against fleas and ticks.
Whittington Veterinary Clinic is here to help protect your dog year-round. Call us at (337) 893-8522 to get started on heartworm prevention today.