Dog-sharing, of course, is as much a misnomer as ride-sharing and home-sharing. These dogs aren’t being passed around for free. But there’s been a flurry of activity among startups that offer dog walking, dog watching, and other dog-related services. Dog-sitting platform Rover acquired dog-boarding company DogVacay in an all-stock deal at an undisclosed price. Wag, the self-declared “#1 Dog Walking and Dog Sitting App for Busy Dog Owners,” has reportedly raised $19 million from two rounds of funding over the last two years.