Dear Daisy Dog During her annual exam, my dog Misty tested positive for Lyme disease on the SNAP test. The veterinarian vaccinated her but did not treat her for the disease. Another veterinarian recommended an antibiotic. Which treatment is correct? Daisy Responds If you had asked one more veterinarian, you might well have received a third recommendation: to conduct a Lyme C6 quantitative antibody test and base the treatment decision on the result. According to a poll conducted in May by the veterinary journal Clinician’s Brief, veterinarians are evenly divided among the three treatment options. Let me explain the theory behind each, to help you become a better informed member of Misty’s heath care team. First, let’s look at the decision not to prescribe an antibiotic but to vaccinate instead. The SNAP test showed Misty had been exposed to Lyme disease. She wasn’t sick, so your veterinarian felt she required no treatment. Moreover, the potential risks of antibiotic use may outweigh the negligible benefits in this situation. Furthermore, no study has proven that treating non-clinical Lyme-positive dogs prevents them from getting sick later. With regard to Lyme vaccination, the SNAP test proved Misty’s lifestyle exposes her to ticks, so your veterinarian vaccinated her to prevent disease in the future. Many veterinarians also recommend a product that kills ticks, such as K9 Advantix or Frontline Plus. The second option, to treat all dogs that test positive, is employed by one-third of veterinarians, because they feel the antibiotic is relatively safe and inexpensive, and they’re not very concerned about bacteria becoming resistant to it in the future. Finally, one-third of veterinarians recommend an additional test, usually the Lyme C6 quantitative antibody test to determine exactly how high the dog’s antibody level is. Levels below 30 indicate exposure but not active disease. On the other hand, if the C6 quantitative test detects antibody levels over 30, most veterinarians treat with an antibiotic. The SNAP test shows only whether the dog has antibodies but doesn’t measure the level. All three treatment options are considered acceptable. Unfortunately, no one knows yet which will prove to be the best course.