It is funny, your little puppy is showing just how a 5 week old Lab would behave. Removing it from its mother and litter mates that soon will make the biting worse, but may have been the best thing in this case. I have been answering questions like yours for a long time, forever in web time. I have material I can paste in to help.
Young Labs, which I know best, and other puppies tend to very bad about
Biting. You see a litter of them, and all the ones that are awake are biting
Another one or themselves. I am not even sure they realize that when they are
Alone, if they quit biting, they would quit being bitten. At 3 to 4 months
They are getting their adult teeth, and it seems they spend every waking
Moment biting or chewing. I maintain a Lab's favorite chew toy is another
Lab. Otherwise they settle for any person they can. They keep hoping to find
One that won't yelp and jerk their hand away, or growl "Bad dog." and clamp
Their mouth shut. Then offer a chew toy. They keep trying despite hundreds
Of corrections. Another good technique is to quit playing and go away. Be
Sure to praise them when they are playing nice and not biting.
You just have to keep on correcting them, hundreds of times, not dozens.
Provide sturdy, safe toys such as Kongs and Nylabones. Avoid things they can
Chew pieces off and choke on them. Keep them away from electrical cords.
Crates are essential for most young Labs and other dogs.
The pet stores are full of toys that many dogs will quickly chew up into
Pieces they could choke on or cause intestinal blockages. If you are not
There to watch, stick to sturdy stuff such as Nylabones and Kongs. Keep a
Close eye on chew toys and quickly discard anything that is coming apart in
Pieces. Rawhide is especially bad because it swells after being swallowed.
These problems are the worst with, but not limited to, large, aggressive
Chewers such as Labs.
Dry dog foods are better for dogs. The hard food cleans their teeth improving their breath and gives the teeth and jaws exercise. Slowly switch him over to one from the canned. Food is a good place to cut expenses on a dog. You should be feeding a puppy chow now. Switching to an adult chow for the
Larger breeds at 4- 6 months, slows growth and may help develop sturdier
Joints.
Your dog definitely should be narrower at the waist than the hips and chest.
You should be able to easily feel the ribs, but not see them. Each dog is
Different. Standard recommendations are a good place to start, but each dog
Must have its food adjusted to its individual needs. See
http://www.purina.com/dogs/nutrition.asp?article=292.
The dry dog foods are actually better for the dogs. It helps keep the teeth
Clean, and exercises the jaws and teeth. If you feed a complete dog chow, you
Shouldn't need to give the dog anything else. Various people foods may only
Add more calories without providing proper nourishment. Look at how many of
Us are too fat too. If you don't want to pay name brand prices look for
Certification of passing the AAFCO tests. Make any changes in diet slowly
Over about a week.
The premium, concentrated foods give you the assurance of a brand name. They
Produce a smaller, firmer stool that is easier to clean up. It is easier to
Maintain weight on a finicky eater. The lower cost foods may actually have
Lower fat and be better for your dog. Many dogs would enjoy eating the larger
Portions you have to feed.
Dogs have trouble digesting the lactose in cows' milk. The plain dry dog food and little else is the best thing for him. You may still have to soften it with a little water for now, but in a couple of weeks he should be eating it dry. Until he is 4 months old, feed him 3 times a day, maybe a quarter to a half of a cup each meal. Take away anything he doesn't eat within 15 minutes. Dogs seldom harm themselves by not eating.