Like canaries in a mine shaft, animals can act as sentinels for human illness. Researchers have wondered if this might be the case for Lyme disease.

Both dogs and people are susceptible to this tickborne disease, suggesting that rates of canine infection may mirror human risk. Using blood tests from dogs in 46 states, scientists discovered that if 1 percent or less of canine tests were positive in an area, then human risk was low. If 5 percent or more of canine tests were positive, then human risk was high.

Such information can be used to direct prevention efforts to areas they’re most needed. Of course, it’s always a good idea to use repellent and to check for ticks after walking through potentially infested grasslands. And if you see ticks on Fido, make sure to check everyone in your household for unwanted stragglers on their skin, not just your furry friends.