While it seems to be commonly thought that dogs scoot on the ground because they have worms, it is much more likely that they could be suffering from distended anal sacs. These two small sacs are located under the skin around the anus. They normally secrete a thin yellow to brown foul smelling liquid. In some animals, the ducts that drain the sacs do not function well, and the anal sacs become distended and painful. If they are not emptied, the anal sacs can become infected (anal sacculitis) and may eventually abscess. This problem seems to be more prevalent in smaller breeds of dogs as well as dogs that are obese, but it can happen in any breed or size of pet. Cats can rarely have anal sac problems as well.
Food allergies, fleas, or other skin disease can also cause your pet to scoot. If your pet displays this unattractive habit, we can usually determine the cause with an examination.