I just read all of the responses to the initial poster. I think one thing is being overlooked, in general. Frequently, when a dog is boarded or must stay at the vet overnight, he/she will be crated. Contemplate the fact the dog will already be a little uneasy with the situation, then think about how being crated for the first time might make him/her feel.
I adopted Tae when she was 13 mos old. She was not crate trained prior to that and, though I've tried several times to crate train her, I've never been successful. Though I have posted on this before, in a nutshell, she has a confinement problem. I even consulted with a great behaviorist on this who has other Boxer clients with confinement issues. Tae panics when crated. Believe me, I tried, mostly for the reason above, but also to protect my house!
Since I am unable to crate Tae, I have been forced to replace a window sill, wood putty three others, as well as part of my staircase, and re-glue a piece of berber carpet she chewed (small, thank gosh!). For months, Tae was unable to "hold it" while I was at work. She didn't have a UTI and she's housebroken and does not have sep anxiety, so my behaviorist conclued she just couldn't hold it. During the months I tried crating her, she was able to "hold it" in the crate (instinct), but for months, I had to clean up her little pee pee puddle EVERY day. Since I was unable to restrict her to a room or the kitchen (long story), she went potty in multiple places on my carpet. Yuck! These are all reasons to crate a dog........chewed items and destruction can add up!
I feel fortunate b/c, for the most part, Tae is a good girl while I'm at work or out. I do wish, though, that I could crate her while away from the house. Overall, she is well-behaved and I just ensure she receives enough exercise. A tired Boxer is a good Boxer!
PS
My former neighbors have a dog who lived out his first four years in a crate, which was kept in a closet. Thank goodness for him, there seem to be no ill effects. Still, though, if crate training is done properly and the dog is not left in the crate ALL the time, use of a crate can be a very postive situation for all parties!