jake hears something behind the door

i brought jake to the vet today for his distemper and rabies vaccines. he tested positive for lyme disease, but our vet does not recommend antibiotics for a number of reasons:
1. the effectiveness of the antibiotics is not known
2. only 10% of dogs actually experience any of the symptoms of lyme
3. they don't want to overuse antibiotics, thus possibly promoting drug-resitant strains of bacteria which would prevent jake from taking any international flights

we are unsure if doing nothing is the right thing to do. i'm going to call dr. lyman, who has treated my parents' dogs for years, but if anyone else has an opinion, please let me know.