My 8 year old Springer always tests positive to the Lyme antibodies. He must have been exposed to it as a pup.
The first year we gave him the necessary shots to help prevent any symptoms. Since then we have never had him take the shots and he has always been symptom free.
He is on a strict K9 Advantix regiment, due to the amount of fleas and ticks in our area. Only one time he did have fleas from a family member's dog but K9 Advantix quickly took care of business.