Annette Kowalczyk, a retiree, and her trusty dog, Beau, were extraordinarily active last month, relishing long walks through her suburban Chicago neighborhood — a pleasant change from last winter, when icy sidewalks and bitter cold made their favorite pastime downright treacherous.

Alas, for poor Beau, a bichon frisé who suffered a nasty tick bite in February, the balmy winter weather also appears to have encouraged legions of ticks to abandon their typically sedentary winter habit of lounging docilely under snow drifts, in favor of feasting heartily on a late-winter canine blood meal.

“The vet said the tick didn’t settle down until he found a juicy spot on Beau’s neck,” said Mrs. Kowalczyk, 74.

“I was horrified,” she added. “It wasn’t like we were walking in the forest. We were on the sidewalk, in my neighborhood.”