It is a very sneaky and tricky disease. False negatives are very common. They are improving on that as the disease and need becomes more prevalent. (There’s a good one that has to be specially ordered. The name escapes me right now. Will share when I find it.)
When we suspect Lyme in the horses we start them on Doxy anyway. Even if the titer hasn’t come back yet. They typically show improvement within 2 wks.
You never want it to get so out of hand that it causes irreparable damage. I know a horse right now that is neurologic from it.
