Your dog’s sleeping style matters.
Sprawlers like to stretch out fully. They need a longer rectangular bed with plenty of open space.
Curlers like to sleep in a ball. They may not need as much length, but they still need enough support under the whole body.
Leaners like to rest their head or body against something. They may enjoy a bed with enough space near a wall, sofa, or bolster.
Side sleepers need a surface large enough to support hips, shoulders, spine, and legs.
For large dogs, rectangular orthopedic beds are often a practical choice because they give more usable surface area.