black and tan

I recently bought a 2 month dobie from a well known pet shop in my area. Recently i was searching body marks to authenticate whether it is a pure breed or not. I noticed there is no black markings on its paw. Is it necessary to have black markings on the paw in a pure breed??

Has anyone seen a puppy with this dark of a muzzle he is a euro his dad is red and mom is black and rust breeder said it should lighten up