Heartworm disease can sound like something far away—something that happens to pets in warmer states or in homes where animals roam freely outside. But the truth? Heartworm disease is a very real threat, even here in Bloomington, MN. And while monthly prevention is simple, there’s a surprising amount of misinformation about how heartworm spreads and how serious it really is.
Let’s clear things up. Below are the most common heartworm myths we hear and the facts every pet owner should know.
Myth #1: Heartworm Only Affects Dogs
It’s true that dogs are the most common hosts for heartworm disease, but they’re not the only ones at risk. Cats can get heartworm, too.
In cats, heartworm disease tends to look different than it does in dogs. Just a single worm can cause severe inflammation in a cat’s lungs and arteries. Unlike dogs, where adult worms grow and multiply, cats are more likely to experience acute respiratory issues due to immature worms that never fully develop. The condition even has its own name in felines—Heartworm-Associated Respiratory Disease (HARD).
One of the biggest challenges with feline heartworm is diagnosis. Cats rarely test positive on standard heartworm antigen tests, and symptoms like coughing, vomiting, or lethargy are often mistaken for asthma or hairballs. That’s why monthly prevention is still the safest route for cats—even if they spend most of their time indoors.
Myth #2: My Pet Stays Indoors, So They’re Safe
If only that were true! Heartworm is spread by mosquitoes, and mosquitoes don’t care if your pet is lounging inside. All it takes is one infected mosquito to enter your home through a door, window, or screen and bite your pet. That one bite can transmit heartworm larvae.
We’ve seen heartworm-positive pets in Bloomington who rarely, if ever, go outside. Indoor dogs still need prevention. Indoor cats? Absolutely.
Mosquito activity in the area can stretch far beyond the traditional summer months, especially with our increasingly unpredictable weather. Prevention shouldn’t stop just because your pet is curled up inside—because mosquitoes don’t stop, either.
Myth #3: You Only Need to Give Prevention During Summer
A lot of pet owners assume that once the weather cools down, they can take a break from heartworm meds. The reality is, year-round prevention is the only way to truly protect your pet.
In Minnesota, mosquito activity often begins earlier in spring and sticks around later into fall than most people expect. And more importantly, heartworm preventives don’t work retroactively. They eliminate larvae your pet was exposed to in the previous month.
Skipping a dose in October because the weather seems chilly could leave your pet unprotected from an infection picked up in September. That’s why veterinarians recommend giving heartworm prevention all 12 months of the year.
Need to refill your pet’s prevention? You can order trusted heartworm medication directly from South Hyland Pet Hospital’s online pharmacy.
Myth #4: Heartworm Isn’t That Serious
Heartworm disease is very serious. In dogs, adult heartworms live in the heart, lungs, and nearby blood vessels. Over time, they cause permanent damage, and severe infections can result in heart failure or death.
Even more concerning? Treatment for heartworm disease in dogs is complex, lengthy, and expensive. It typically involves a series of injections, months of strict rest (no walks, no playtime), and regular monitoring. And not all dogs are good candidates for treatment, especially those with advanced cases.
For cats, there’s no approved treatment at all. That means prevention isn’t just the best option—it’s the only option.
Myth #5: I’ll Know if My Pet Has Heartworm
This is one of the most dangerous assumptions. In the early stages of heartworm disease, there are often no visible symptoms. Dogs can go months—even years—without showing signs. By the time coughing, fatigue, or weight loss becomes noticeable, the disease is often advanced.
Cats may show vague signs like intermittent vomiting or trouble breathing, but those can be easy to miss or misinterpret. Some cats may show no symptoms at all before a sudden, fatal reaction.
Routine heartworm testing is a must—every year for dogs. Testing catches the disease early, when treatment is more likely to be effective, and confirms that your prevention is working as expected. This is a standard part of annual wellness care at South Hyland Pet Hospital.
Protect Your Pet with Simple, Year-Round Heartworm Prevention
One monthly dose is all it takes to protect your pet from heartworm disease. If you’ve missed a dose or need to get started, South Hyland Pet Hospital is here to help. We’ll guide you in choosing the right prevention and make it easy with home delivery through our online pharmacy.
Call us at (952) 884-1868 or request an appointment online to keep your pet protected all year long.
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