Are Dogs or Wolves Really Den Animals?
Dens, Nests, and Resting Places
I think it’s important for every dog to accept a crate, but I’m not a fan of using crates except in limited circumstances. When confinement is required, I prefer to limit a dog’s access to other areas with a barrier like a baby gate or a large x-pen. For vehicle travel a crate is a great choice if it is crash tested and secured in the vehicle.
Contrary to popular belief neither dogs nor wolves are “den” animals in the way it has been popularized. “Denning” is a seasonal maternal behavior and the den is only used for newborn puppies for about 8-weeks before being abandoned. From 8-20 weeks the puppies are moved to an area with a “nest”. After 20-weeks I think it would be more accurate to say dogs seek out a resting place. While there may be a small percentage of dogs that would choose a protected area such as a crate for resting this is not the norm. If this was the normal behavior for dogs there would not be the strong emphases on “crate training”. Choosing a resting place that is isolated is different from choosing a crate.. Sadly way too many people believe a crate is a necessary "tool" for confinement.
When necessary to use a crate the goal should be to put the puppy in the crate when then are ready to rest. Actually I want them thankful for the quiet and rest time. I would have scheduled a play session earlier, than a nice lower excitement activity after that and maybe a small meal. Then I would place them in after their regular elimination when they are ready for rest. At that point I would shut the door because if I got my part right they will welcome the opportunity to rest. If the puppy or dog is not tired, they can view the crate like a prison on lockdown, so do not abuse its use, but rather use the crate after they have exercised first and are ready to rest.
Crates should only be used for short periods of time when necessary for a dog that cannot be supervised.
A crate should be large enough for a dog to stand, turn-around (without touching the sides), lie down comfortably and strech out.