Heartworm testing

Q: My puppy is 15 weeks old now and she got her last Parvo/Distemper/Boardetella vaccine and now she just needs her Rabies and Lepto vaccines. She received her heartworm pill as well as Frontline yesterday and our vet here is really great but I'm just a little concerned about something. I asked the vet when my puppy would have her first blood test at our first visit and I believe he said next time, and I brought her in a few days ago and he said she didn't need a blood test and was healthy. I've had dogs in the past and this seems strange to me? I'm pretty sure my puppies have always had their blood tested during their first or second vet visit. Mainly to check for heart worm before administering the heart worm preventative pill. Am I wrong? If she definitely does need her blood test how can I go about convincing him to check her blood, or should I find a new vet?

A: Our currently used heartworm tests are testing for antigen produced by adult heartworms or in some cases newly produced baby heartworms called microfilaria. It takes at least 6 months for heartworms to become adults or produce offspring so testing prior to 6 months of age is not necessary.