There is no such thing as a free puppy. All puppies need shots, flea prevention, heartgard for heartworms, food, bedding, crates, & to be spayed/neutered. Rottweilers eat a lot. I spend $50 a month to feed mine not counting all of the above listed things. Rotts are wonderful dogs, but need extensive training due to their powerful size. You might want to research the breed better before you find a Rott. It doesn't sound like you are ready for the responsibility.
