Health & WellnessCan I get a heartworm prevention prescription online or at a vet?
You will need to go to a vet as it requires a negative heartworm test before it can be prescribed. This is a simple, fast blood-test that will let the vet know it is safe to start preventive medication.
Why this is required is if your pet already has heartworms and is given the medication, it can kill the worms too quickly which can cause blockages of the blood vessels leading to potential stroke or death. Making sure your pet is negative first will ensure it is safe to administer.
Updated on September 24th, 2025