My 2 year old dog went in for a check-up today. She tested positive for Lyme on an Idex 4dx snap test. She has been a bit off, but nothing serious. I routinely test for Lyme due to our tick-laden lifestyle.

My vet didn't think I should treat without classic symptoms. He said the current protocol didn't call for treatment absent lameness/lethargy.

She has not been vaccinated for Lyme.

Any wisdom? I am thinking I should treat. I would be grateful for links/references to help me with this decision.

I have myself and animals tested once a year for Lyme, it is almost epidemic in my area, for humans and animals, including horses.
Anyway, did they say if she was high positive? Did they just do the SNAP test? and not a titre?
My last dog had an over seven year battle with Lyme, and what turned into chronic RMSF.
Amber (my current dog) has been Lyme positive since a young pup, and I believe this has contributed to her reactivity, she did not have any overt signs when I got her. She was also positive for anaplasmosis.
So from my experience with Lyme, including with humans, with horses, with dogs. You say she "is only slightly off" to me that means she is symptomatic, animals tend to be very good at hiding pain, what may be slightly off may in fact be hiding what we could consider fairly moderate pain. My animals did not have the classic doggie signs of Lyme either, one had a very transient literally 3 steps of lameness on the same front leg. When I accidently bumped his wrist and this very stoic dog cried cried out did I suspect lyme and his snap test was super high positive turning four minutes before the control did.
Amber stretches excessively and mopes, no lameness. Amber was also high positive.
The vets in my area always treat sympotomatic or not, then we do titres yearly or if I feel she needs one, to monitor the disease. With my last dog doxycycline did not agree with him, thus setting him up for chronic lyme and rmsf, another antibiotic years later knocked down sx of both about 85%-90%. Amber is able to have doxy, but this round where using the antibiotic my last dog used although its pretty expensive. Amber has also (after diagnosis and treatment, and titres) been vaccinated with the second generation lyme vaccine. My vet and I had a long discussion about this and felt it was in her best interest. Lyme can cause severe kidneys problems in dogs and the typical sx are bed wetting, refusal or reluctance to go out, non interest in walks, to collapse. I can't tell you how many dogs that have been rushed to the vet in my area with "sudden collapse" only to be tested and positive for lyme and in the final stages of kidney failure. So... I treat for each new diagnosis, for each flare. But... my vets are also very well educated on lyme, and see hundreds of animals a year with it. When I was in college because of my dogs experience with it, any chance to write a research paper I did it on tick borne disease, one of the most interesting things I was able to find was this: for 1-3 months Lyme stays in the joints, if untreated for 3-6 months it goes into the organs, if untreated for 6 months or more it goes into the brain and CNS. This fact is controversial as many feel a dog cannot get neuro lyme I believe they can. So in a long winded way (sorry), to answer your question, I treat symptomatic or not, then use titres to determine additional treatment for flares etc. Lyme is a very bad diseas and it can be fatal in worst case or cause life long problems. jmho.

Even if it has been treated I would watch for symptoms.

I am sick with Lyme since 2005 bite and 1 month standard treatment.

Researchers are finding out that it takes more forms and hides.

Wow, Lynne you only had one month of treatment? In my area for humans with lyme they are doing 3 months of IV antibiotics (via picc line), I know quite a few people with chronic lyme that go on IV antibiotics for flares. A lot have delay in dx because if its neuro, it shows up on spine tap, not bloodwork. They also do both ELISA and western blot for testing. It is an SOB of a disease. Hope you feel better.

Thank you. I started her on doxy. Not sure if it's just my imagination, but she seems much more active already. She is tolerating the doxy well so far.

Thank you for your input.

Glad to hear she is feeling better.