I need to know how to expel my dogs annal glands myself
Why Do Dogs Rub Their Butts On Floor?
Your dog either has Worms that need to be treated or it's Anal Glands are full and need to be emptied. That's why it's dragging it's rear end on the floor.Take your dog to the vet and they will tell you for sure.If it's Anal Glands are full and you don't take it to the vet to have them emptied, then they can get Infected and Impacted and they can become very painful. 
Dogs rub their butts on the floor because they have an annal itch its a itching inside their butt. Humans get annal itch to.hope this helps.
That is funny...but to scratch it...they can't reach it with their paws obviously...:)