Physical examination is much needed to say something about diagnosis of hard lump in your dog. Most common type of lump on dogs is lipoma which are round fatty tumors in the skin of dogs. Lipoma don't harm and dogs don't feel any pain. No treatment is recommended but if the size of the lump is large or location is disturbing then surgery can be performed. It will be better to take your dog to vet for proper diagnosis and treatment of lump in your dog.
