But contrary to popular belief, dogs are not "den animals." Although some dogs learn to like a crate right away, others might need some acclimation.
Some dogs might be easy. Just play a few games, toss a few treats and the dog is fine.
Some dogs might need to learn to acclimate in teeny tiny increments (don't ask them to go in right away).
Reward the dog for just walking by the crate. Reward the dog for looking at the crate and so on.
See details here: http://www.clickersolutions.com/articles/2001/crate.htm
Of course this can take some time. If your dog needs to be confined for any reason while you are still working on crate acclimation, see some ideas here
If a dog still has trouble acclimating to the crate in increments, we might need to start with confinement without the crate. Note the below suggested protocol might also help a dog who needs to learn to relax in a crate when pet parents move away from the crate.:
Start with a relaxation protocol - like Dr Karen Overall's: http://www.stubbypuddin.com/2013/12/today-is-great-day-to-start-dr-karen.html
Then a small, see through barrier. Something like this that will be open on all sides but one: http://amzn.com/B0046V6KI0
Then continue out of site exercises, stay exercises, relaxation protocol, etc.
Later use an exercise pen that has a wide opening on one side.
Next start closing it in but only in increments and keep trying the out of site exercises.
Later close the ex pen all the way and keep doing the exercises.
A remote treat dispenser like a Treat and Train or Manner's Minder can be useful for this - so you can also do out of site rewarding.
Then try a room with no barrier
Then a room with barrier
Once pup does fine with that, start decreasing the size of the room.
Next start with half of a crate. Details here:
Then you might be finally ready for out of sight with a crate. But try a super duper large one so the dog won't feel so confined.
Once the dog does fine in a very large crate, you can reduce the size to something more manageable. But not too small of course.
I would not do the standard "just big enough to turn around and lay down". I'd give the dog plenty of room - if that is what he/she wants. Some dogs prefer smaller spaces.
Also experiment with different types of crates - plastic, wire, canvas (not very secure), etc..
A video representation of the above: http://youtu.be/YjUZfJ9ZZwo
Stay tuned for more on crating. Future posts were be here: http://www.stubbypuddin.com/search/label/crating
Also see Malena De Martini Price's book on Separation Anxiety for some ideas for dogs who don't want to be left alone