lymes Question

I took my dog in to the vet on Monday to have his eye checked. He had got a seed in it while training this weekend. The eye will be ok. I also had them test for hartworm and lymes and give him the last vac shots. They told me the the hartworm cameback – but Lymes came back + He has had no signes of it. We did put him on some Med for it. Has any had to deal with lymes before if so any help would be graet. I just hope he kepts showing no sighs of it. It to close to rooster shooting time for him to be laied up.