Lyme's Disease Question

A friend who isn't an RTFer asked me to post this. Her 14 month old was recently diagnosed w/ Lyme's. Titer is 66, which vet says indicates "having the disease, as opposed to just exposure". The dog hasn't been vaccinated. She also shows no symptoms. There were a couple days of feeling a "little punky", but absolutely nothing since then.

Their home-visit vet is very circumspect of her requiring the doxycycline treatment and so I'm posting to try and get a general (vets especially please!) consensus of what is appropriate for this dog.

Thanks!

M