A crate replicates the feeling of a den. It should be big enough for the dog to lie down, stand up & turn around. It should not be so big that they will be tempted to soil in it.
An ex-pen is bigger & can be placed in a corner of the room. This can help foster independence, by letting the dog amuse themselves. Unless the dog is house broken, I would not leave the dog in the ex-pen for extended periods.

Wiley answered on 1/16/13. Helpful? / 0