I got a call from the Vet today. Time for a round of good news...bad news...
The good news is that Oscar is not carrying microfilaria. Which means he cannot give it to other Dogs.
The bad news is he tested positive for adult worms (the antigen at least). We're putting him on Heart Guard starting tomorrow.
We got him from a Rescue operation who got him from Mississippi when he was 5 months old. He might have had them then. We put him in inteceptor as soon as we got him, so that's why there aren't any microfilaria, but they don't test dogs before six months.