A dog scoots its bottom across carpet or other surfaces to alleviate the symptoms of itching and irritation that are caused by a variety of problems. Anal sac problems, fecal contamination and rectal prolapse can all cause these behaviors.
Anal sac problems including inflammation, blockage and abscesses can be painful to the dog and cause it to scoot on its bottom to try to alleviate its discomfort. The dog may also chew or lick the area, and the area may become swollen. A vet can express the sacs or give antibiotics to treat an infection in the anal sacs. Hot compresses may also help.
When feces becomes matted around the dog's bottom, it is known as fecal contamination, which can be very uncomfortable for the dog. The dog scoots on its bottom to try to free the area of feces. If this is the case, trimming the dirty hair away is generally a good option — especially if it is too matted to wash away.
Rectal prolapse protruding from the anus can also cause scooting behavior. This type of problem occurs when dogs are constipated and strain too hard or after a bout of intense diarrhea. When prolapse occurs, a visual mass can be seen hanging from the dog's rear. This condition requires immediate evaluation by a vet.
There are other reasons a dog may scoot on the carpet on its bottom. Infestation with worms, injuries and anal tumors can cause scooting.