Most of the negative side effects from Imizol are from improper administration of the drug. I printed out the instructions for my vet and he was glad because he had not given a shot in years.
You must change the needle after the draw. It should be given IM in the butt and sides rotated, the injections given exactly two weeks apart.
If you want a lot of good information, check out the tick list. I personally wouldn't waste money on a PCR. I also would not treat some positive titres. You can call and talk with Dr. Holland if Protatek did the test. In addition, you need to know what the blood panel shows from normal blood work.
Fortunately, one of the Tick list's administrators (and I believe the founder) is Dr. Beckett in Austin who has treated hundreds of greyhounds.
Tick List