Well, it depends on what the body type of the pitbull is. Some pits are short and wide, some are taller and skinny, abd some are just huge! So take that into consideration. The dog will have a mix of traits from both breeds, but it's hard to say what traits from which breed, you'll get. Both breeds have big heads, so its safe to say that his head will be huge. Rottys have big bodies, and pits have very well defined muscle tone, so hopefully there will be a mix of both. You'll pretty much have a VERY intimidating looking dog!
