He has gotten ahold of it a couple of times (and one other one I had to toss last week). I keep my eyes open as much as I can and try to keep the baby (almost 2 years old) close to me when he's drinking, but sometimes he wanders around the backyard with his cup and puts it some place Dozer can get it.
C'est la vie! Puppies will be puppies and toddlers will set their sippy cups down. I've just got to grow an extra set of eyes.