Some dogs need their anal glands expressed, as Carrie suggested, while other dogs express them theirselves when they poop. My pug needs her anal glands expressed on a regular basis, or else she stops walking on her feet, and begins to only scoot on her rear to get around the house. It's funny to watch but it's also pretty grose. If it's not parasites, have your vet show you how to expell the anal glands yourself so you don't have to take the pup to the vet to have it done every time if you wanted.