Typically they take blood from the leg. We only need to do hearworm testing every other year here. I think Angel will be due in 2013. It will be interesting, because he does not like the vets either! He has to be muzzled. The vet said it's not worth taking the chance. It's too bad, because I am sure that add to his anxiety about being there. Luckily, he hasn't had to go much! Just the usual shots etc.
He should be fine. The technicians usually know how to handle the situation and assist the vet.