Thanks for that Fi, I forgot Laura (who is a member here!) has a good crate training page too.
Cathy gives a good summary of what I think is 'best practice'
. Crate train so that your dog is comfortable with being crated, relaxed, and can be left for longer periods if necessary (for example, even for a short 1-hr flight a dog would probably be crated for 4 hours counting the trip to airport, early check-in, waiting in the hold, flight itself, landing and waiting for the dog to be delivered to you). Ideally, once trained, I think it is much nicer for the dog to be left at home in a room rather than a crate (but with the crate there). A crate-trained dog tends to be an un-anxious dog, relaxed when left alone anyway. My two mostly just sleep though I can tell when they've been playing as pillows might be all over the floor or toys taken out. It is ideal I think for them to be able to stretch, move about, change position in the space of a room. But then, for you to be able to crate when needed for whatever reasons.
BTW mine are home-boarded with Tara's (TKC's) mother in Dublin and they can be crated as needed at night, when they share a roomy crate. So I know they are fine staying with someone else and being crated, too. It is nice to know they will be calm if crated rather than anxious and expecting to be on a bed!! :lol:
To be honest I've found most dogs even ones never crate trained will accept a crate -- I need to use them regularly whenever I have a rescue dog around. I transport in crates and sometimes need to crate in the house. Most will be OK and it is clear that with some minimal effort most adults too can be crate trained.
If you have ever been to a dog show you will see all the dogs just laid-back and sleeping in crates, oblivious to all the activity around them!!