How long is too long in a crate?

Question
I've had a male beagle puppy a little over a week now, he's 9 weeks old and I spent all of last week home with him and getting him used to his crate.  Today was my first day back to work so he was in his crate 4 hours, my husband came back for lunch, walked him,  and played with him and then he went back in his crate another 4 hours.  When we got home and let him out he was ferocious!  It seemed like a mini temper tantrum.  Biting more than normal, attacking our feet when we would walk, not anything like he's been in the past.  Should I gate up the kitchen so he has more room?  I'm concerned that his behavior will get worse as he spends more days in his crate.  He's great in the crate at night.  He only whines when he needs to go outside to potty, I'm concerned all night and now 8 hours a day is too much.  Will he adapt or should I consider other arrangements?

Answer
I have routinely left puppy after puppy starting as young as 7 weeks 4-5 hours in the crate with no problem.  You may be having a question of your authority.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, try these:

''Elevation for small puppies:  Sit on the floor and gently put your hands around your pup's middle, below his front legs, and lift him up.  He is facing you.  Hold him for 15 seconds.  Repeat until he no longer struggles.  If he is past 10-12 weeks, lift his front feet off the ground, but don't pick him up.  

Cradling for small puppies:  Hold your puppy gently on his back, as you would cradle a small baby.  If he struggles, hold him firmly until he quiets for 10-15 seconds.  With larger pups, you can do this as your sit on the floor, with your pup between your legs.

Quiet lying down:  Place your pup on the floor on his side, with all 4 legs pointing away from you.  Use your hands on his neck/shoulder area and middle, to hold him in this position.  When he is quiet, praise him.  Lengthen the time that you keep him quietly in this position.  When he accepts this position well, handle his paws and muzzle, while keeping him quiet.''

The quotes mean this isn't my original work.  It is copied from my Puppy Raising Manual.  I have long used these or minor variations of them, and they are very effective.  You may want to give him a belly rub while he is on his back too.  Helps bonding.  There is a big difference between him rolling over and demanding a belly rub, and you choosing a time to roll him over and rub his belly.  The latter cements your place as pack leader.