Written by Krista Vernaleken, VMD
So my dog had a tick on him, and it was engorged. Now what?
First of all, not all ticks carry diseases. Second, not all disease-carrying ticks were attached for long enough to transmit Lyme. There is unfortunately no characteristic sign such as a red ring that appears in humans showing that the tick transmitted Lyme to the dog. It takes between 2-5 months for dogs with Lyme exposure to show up as positive on antibody tests. So at the time that a tick is noted, the best plan is just to remove the tick, check the dog for any additional ticks, and continue to check daily for ticks as we recommend for all dogs. Reapply tick prevention at your normal intervals, and be super vigilant for additional ticks. There isn’t anything you can do about the one that was attached. About 95% of dogs “infected” with Lyme (and positive on testing) NEVER develop signs of Lyme! This is not to say that Lyme infection can’t be serious or that prevention is not completely worthwhile. It is just to say that infection is not a guarantee that a dog will become sick.
When they do become sick, it is typically in that time frame of 2-5 months after infection. “Classic” Lyme disease is fever and limping (due to joint pain and swelling that often occurs in the joint(s) closest to where the tick was attached). A rare form of Lyme disease causes kidney failure. This form is much less common than the “classic” form, but we do monitor Lyme positive dogs for it very closely with regular urine checks. There have been a few reported cases of heart, neurologic, and skin-related complications, but these are uncommon enough that they have not been fully studied. No chronic form is known to exist, unlike in humans. So, when a dog tests positive for Lyme, this means that they were EXPOSED to Lyme, and their body created antibodies (which is what we test for). It doesn’t mean that they HAVE Lyme. They only have Lyme if they have clinical signs of Lyme disease (fever, joint pain, and/or protein in the urine) and have an appropriate response to treatment (rapid resolution of the fever and joint pain when given antibiotics). This is why many vets do not treat dogs that are simply positive for exposure with antibiotics. They may recommend further testing (urinalysis, sometimes bloodwork, sometimes more specific antibody levels to determine the magnitude of exposure).
Treatment consists of one month of an appropriate antibiotic. After treatment, they do not experience any long-term effects from the disease. The only problem that we continue to monitor them for is kidney disease, and for this reason we recommend checking their urine every 3-6 months. Some dogs do experience what seems to be a “recurrence” several months after treatment – at this point we are not sure whether this is truly a recurrence or a new infection.