You need to acclimate them slowly and make it a safe/fun place, not a prison. Start by feeding, treating in crate, leaving door open. Put toys in so pup goes in and out to get toys, always get pup to go in by self (use treat) and use command word so pup will go on command in time. Start closing for short periods, staying close (Trick is easier if pup is due for nap time), lengthen times, but never respond to whining, always wait till pup is quite before letting out.
If done properly pup will go in crate at will and nap or just to get out of traffic |