My 5-month-old border collie bites my ankles when I walk around the house. It's not playful — she's herding me. It hurts and I don't know how to stop it.

She's herding you because you're moving and she's understimulated. Border collies are working dogs that need 90-120 minutes of exercise and mental work daily. If they don't have a job, they'll invent one — and herding your ankles is the job she picked. Two-part fix. First, stop moving when she bites. Stand completely still. Movement is the reward. When she releases, wait 3 seconds, then move again. If she bites again, freeze again. You're teaching that biting makes the sheep stop, which is the opposite of what she wants. Second, give her a real outlet. Teach her to herd a ball instead of your feet. Roll a ball across the floor and reward her for chasing and nosing it back toward you. Do this 10 minutes twice a day. After a week, when she starts going for your ankles, redirect her to the ball immediately. Most border collies transfer the behavior in 2-3 weeks if you're consistent. If she's still doing it after a month, she's not tired enough.