Some breeds have more problems with them . The dogs i breed Cavalier King Charles Spaniels are the worse of any breed, they have to be done monthly. Diet can make a difference, if a dog has soft or loose stool it is more likely to happen. One of the best things you can do to prevent is feed her 2 table spoons of canned pumpkin everyday (not pumpkin pie filling, plain canned pumpkin) What is suppose to happen is when stool is passing though digestive tract it express the anal glands when passing over them, if stool is soft it willn't express the gland. Pumpkin is suppose to harden stool. It is very easy to learn how to express glands yourself, or find a dog groomer who does it, and of course your vet does it. Here it is cheaper for clients to bring dog for grooming then have vet do it. While we want to believe our Vet became a Dr for their love of animals it is a business for profit.