From a Veterinarian’s Perspective
Heartworm disease is one of the most misunderstood conditions in veterinary medicine. While many pet owners are aware of it, there are still plenty of myths that lead to confusion—and sometimes, preventable illness or death in pets. As a veterinarian, I often find myself clarifying what heartworm is, how it works, and why prevention is so important.
Let’s break down some of the most common myths and compare them to the truth.
MYTH #1: “Heartworm only affects dogs.”
TRUTH:
While dogs are the natural host for heartworms, cats can get heartworm too. In cats, even a small number of worms (sometimes just one or two) can cause severe inflammation in the lungs and blood vessels—this is known as Heartworm-Associated Respiratory Disease (HARD). Unfortunately, cats often go undiagnosed or are misdiagnosed with asthma or bronchitis.
MYTH #2: “My pet stays indoors, so they don’t need prevention.”
TRUTH:
Heartworm is spread by mosquitoes, not through direct contact with other pets. Mosquitoes can—and do—get inside homes. Indoor pets are still at risk. Studies have shown that a significant number of heartworm-positive cats and dogs are primarily indoor animals.
MYTH #3: “I can just treat it if my dog gets heartworms.”
TRUTH:
Yes, heartworm disease in dogs can be treated, but it’s costly, time-consuming, and risky. Treatment involves:
- Multiple vet visits
- Painful injections
- Strict rest for weeks or months (to avoid deadly complications)
- Risk of lung damage or embolism as worms die
In cats, there’s no approved treatment for adult heartworms. The only option is supportive care and managing symptoms. Prevention is far safer—and cheaper—than treatment.
MYTH #4: “If my pet isn’t showing symptoms, they must not have heartworm.”
TRUTH:
Heartworm disease is often silent in the early stages. In dogs, symptoms may not appear until the disease is advanced. Common signs include:
- Coughing
- Fatigue after exercise
- Weight loss
- Difficulty breathing
- Collapse (in severe cases)
In cats, signs can be vague or sudden, including vomiting, coughing, or even sudden death.
Regular testing (yearly in dogs) is the only way to confirm your pet’s heartworm status.
Veterinary Recommendations: What You Should Do
- Start prevention early: Puppies and kittens can begin heartworm prevention as early as 8 weeks old, before 5 months of age.
- Keep up with yearly testing for dogs, even if they’re on prevention if you want to be sure.
- Use veterinary-approved preventives—monthly oral or topical medications, or long-lasting injections (for dogs).
- Don’t rely on symptoms alone to detect infection.
Conclusion:
Heartworm is 100% preventable, but not always treatable.
As veterinarians, we’ve seen too many heartbreaking cases that could have been avoided with simple, consistent prevention. Whether your pet is young, old, indoors, or outdoors—heartworm protection is a basic part of responsible care.
If you’re unsure about your pet’s heartworm status or prevention needs, talk to your veterinarian. We’re here to help you keep your pet safe.