Heartworm in Dogs and Cats: Why Testing Comes First

Heartworm disease is one of those conditions that owners hear about constantly but rarely understand in any detail beyond "give the monthly chewable." It is a real parasite, spread in a specific way, and testing plays a bigger role in managing it than most people assume.

How a pet actually gets heartworm

Heartworm is spread by mosquito bites, not by contact with other animals. A mosquito picks up immature larvae from an infected animal and passes them along the next time it bites. That is the only route of transmission. A dog or cat that never goes outside is at lower risk, but not necessarily zero risk, since mosquitoes get indoors too, and it only takes one bite from an infected mosquito to start the process.

The tricky part is that an infected pet can look completely normal for a long time. Heartworms take months to mature inside the body, and symptoms, when they eventually show up, tend to be vague at first: a cough, less energy on walks, weight loss. By the time a dog is visibly sick, the worms have often been established for a while, which is exactly why waiting for obvious symptoms before testing is not a reliable strategy.

Why testing happens before a preventive starts

Woodsprings Animal Clinic offers heartworm testing and heartworm treatment. Testing before starting or renewing a preventive is standard practice, and it is worth asking your vet directly why that order matters for your specific pet and which test they use. It is a fair question, and a good vet will walk through the reasoning rather than just running the test as a formality.

Why prevention is worth the consistency

Treating a heartworm infection once it has taken hold is a longer, more involved process than preventing it in the first place, since by that point the worms are already established in the heart and lungs rather than being stopped early. That gap between prevention and treatment is the whole reason vets are so consistent about recommending regular testing and staying on schedule with a preventive, rather than treating it as optional once the weather cools down.

Tablet or injection: worth a direct conversation

The clinic carries both heartworm tablets and heartworm injections. The two work differently, cover different time periods, and suit different households and pets. Rather than guessing which is better, ask your vet to lay out the practical differences for your dog or cat specifically: how often each needs to be given, what it covers, and what fits your routine.

• How long a single dose or injection is meant to protect your pet
• Whether the option also covers fleas, ticks, or intestinal parasites
• What a missed dose means for your pet's protection
• Whether a cat's risk and options differ from a dog's

Cats are not just small dogs here

Owners of indoor cats sometimes assume heartworm is strictly a dog problem. It is worth asking your vet specifically about a cat's heartworm risk and options, since cats can be affected too and the disease can present and be managed differently in cats than in dogs. Do not skip the conversation just because your cat never sets a paw outside.

What a testing visit actually involves

A heartworm test is typically a straightforward blood draw, often done during a regular visit rather than requiring a special appointment on its own. There is usually no need to fast your pet beforehand or change anything about your normal routine that day. For most owners, the test itself is the easy part; remembering to schedule it on a consistent basis is the part that actually takes discipline.

Mosquito season is not a single month

It is easy to think of heartworm prevention as a warm-weather task and let it slide once temperatures drop. Mosquitoes do not follow a strict calendar, and a single warm week in an otherwise cool month is enough for them to be active. Keeping prevention consistent, rather than starting and stopping with the weather, is the simplest way to close the gap.

If you are not sure whether your pet's testing is current, or which prevention option they are on, that is exactly the kind of thing worth confirming at your next visit rather than assuming it is handled.