It is his den, his hideaway and his personal spot and assuming you have trained him correctly, will never worry about limited confinement in a dog crate. Just see it as his bedroom within your house as that is kind of how your dog will come to see his crate.
If you watch a dog being trained to use a dog crate and see how he ends up being in there of his own choosing more often than not, then it would take any thoughts of it being cruel to put your dog in a crate right out of your mind.
Any age not just a puppy
Crate training is not just for puppies. Adult dogs can take to a crate far quicker than you would expect if trained in the right manner. They will need to be left alone awhile to explore the crate and free to sniff it and not feel any threat from it. Once your dog reaches the point that he is not wary of it, you are ready to crate train your dog.
The main purpose of a dog crate is confine him in his early months when he is at his most destructive, and to housetrain him generally, and using the dogs own instinct of not wanting to use his eating space as a toilet as a way of teaching him to go outside to powder his nose.
The best kind of dog crate is a wire one that is just big enough for him to stand and freely turn around. Any bigger and it could be counterproductive.
Size it up
Always remember if you are buying a crate for a puppy that he has some growing to do, so buy one that accommodates him for when he is fully grown. However while he is still a puppy, you will need to limit his space so he cannot think about defecating up one end and keeping himself to the other side. He needs to know that if he defecates in his crate it will affect him. So best thing is to block off a couple of feet from the far end, leaving him just enough room to comfortably turn around.
No temper allowed
What you, as the trainer, need to do is exercise maximum patience and resist scolding when he gets it wrong. There is much too crate training a dog although not difficult to learn how to do, it would take a far more concise account then this to teach you. Read here for a detailed stage-by-stage account of how to crate train your dog. Read more here.
Family affair
Some dogs can be trained in days, others it takes several weeks, so from your part, you and the rest of the family need to be involved and fully informed on exactly what to do and what not to do as inconsistent training will only send him backwards and prolong the crate training process.
With luck, patience and self-discipline also, you could have your dog crate trained in no time at all.
It is important everyone in the household knows the rules of crate training and yours and the family’s patience will be sorely tested, but if someone lets him out for say whining, then they are teaching him that whining gets him out and undoing your hard fought progress.
Ensure nobody in your household spoils the work you have put in by introducing inconsistent practice. As much as possible you stay in charge of his crate training so as not to confuse him with inconsistency.
Be prepared
Ensure that you fully understand the function and purpose of crate training and do not just start by throwing him in a crate while you learn. Learn first. He must not ever be allowed to be locked up for long periods especially during training. It is a gradual process but gradually you will get him there.