A working dog with a short coat and no body fat
Dobermans are muscular, high-drive, and famously lean. They also have almost no undercoat and very little subcutaneous fat, which means they get cold easily — much colder in a crate than a retriever or a shepherd at the same room temperature. A wire crate on a tile floor will have a Doberman shivering by hour two. Use a raised cot-style bed or a thick orthopedic pad, and don't be surprised if the dog burrows into blankets.
The 42" or 48" crate suits most adults (60–100 lb). Males often need the 48"; females fit the 42" comfortably.