Every dog over about 7 months old needs a heartworm test once a year, and again before starting or restarting a preventive, because a blood test is the only way to know a dog is free of heartworms. Petfolk Veterinary & Urgent Care - Concord is a vet clinic at 2425 Herrons Nest Pl NW, Suite 100, Concord, NC 28027, and it runs the test in its in-house lab from a small blood sample.
Heartworms are long, thin worms spread by mosquito bites. They live in the heart and the large blood vessels of the lungs and can damage both for months before a dog shows signs. The American Heartworm Society reports that cases persist nationwide, and its 2025 survey ranked North Carolina among the top ten states.
Call (980) 360-2922 or book online.
Why test a dog that takes prevention every month?
Doses get missed, spat out or given late, so a yearly test confirms the plan is working and catches an infection early. Some preventives can cause a reaction in a dog that already has heartworms, which is why Petfolk Concord checks for a current test before approving more. The heartworm prevention page compares product types.
What will the Concord team ask before the test?
The doctor or nurse starts with prevention history, because gaps change when the next test is due.
Which preventive does your dog take, and when was the last dose?
Were any doses missed, late or spat out?
Has your dog traveled, or spent time with a rescue group or foster home?
Any cough, tiredness on walks or weight loss?
Bring the box or a photo of the label. If you switched brands during the year, say so.
A few drops, drawn in seconds
The blood usually comes from a leg vein, and most dogs handle it quickly. Fear-free handling is standard at every Petfolk clinic: a slow approach, treats and a calm hold rather than force. If your dog needs other lab work, the same draw can often cover it, which our blood work page explains.
They even went ahead and updated his vaccines and did a heart worm test Torie R., Google review
What does the heartworm antigen test detect?
The standard dog test looks for antigen, a protein released by adult female heartworms. The Companion Animal Parasite Council notes that a positive result points to an active infection, not just past exposure.
Antigen only shows up once worms grow into adults, about 6 to 7 months after the infecting bite. So puppies under about 7 months can usually start prevention without a test. A dog that missed doses is often tested now and again about 6 months later. A negative result covers the past, which is why testing repeats every year.
Heartworm in Cabarrus County
In Cabarrus County, 0.72% of dogs tested in 2025 were positive, according to Companion Animal Parasite Council data. At Petfolk Concord, 33% of wellness visits for adult dogs aged 1 to 7 included a heartworm test from October 2025 to September 2026, and the in-house heartworm and tick-borne disease test was the most-ordered in-house lab test. Puppies are tested less: 3% of puppy wellness visits at Petfolk's Charlotte-area clinics included one.
What happens if my dog's test is positive?
The doctor confirms a positive with a second, different test, because no single test is perfect. Next steps often include:
A test for microfilariae, the baby worms circulating in the blood.
Chest x-rays of the heart and lung vessels.
Blood work to check organ function.
Strict rest, since exercise raises the risk of complications while worms die off.
Treatment follows the American Heartworm Society's protocol and takes several months. It works for most dogs but is much harder on them than prevention.
Cats need a different test
A negative antigen test does not rule out infection in a cat. There is no approved heartworm treatment for cats, so Petfolk Concord focuses on monthly cat-safe prevention.
What the test costs
The test is usually run at a wellness exam, which starts at $99 or is included with PetfolkCare. The test itself is a lab charge on top. You'll get an estimate before any test or treatment. The final bill can differ if the plan changes during the visit.
Collapse or dark urine: go now
Go to a 24-hour emergency hospital if your dog suddenly collapses, struggles to breathe, has pale gums or passes dark brown urine. With heartworms, those signs can mean worms are blocking blood flow. Petfolk Concord is open 8 AM to 6 PM, seven days a week, and has no overnight care.
Book a visit at Petfolk Veterinary & Urgent Care - Concord, or see all veterinary services in Concord.
Heartworm test questions, answered
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