Is 4 weeks to young?

Yes, 4 weeks is MUCH too young. He should just be working on weaning right now and shouldn't officially leave his mother for at least 2-4 more weeks. I recently aquired a puppy that was 4 1/2 weeks old. I would take him to the vet now for a wellness check and a worming, and moisten his food with puppy milk replacement formula for about the next two weeks, and the slowly begin phsing the formula out of his diet. Then, as soon as he's had his shots, get him in a puppy class and socialize the crap out of him...he needs to be around other dogs to make up for the time he missed away from his mother and siblings. Puppies taken away from their mother at a young age who don't receive plenty of dog socialization can grow up to have considerable behavioral problems...they won't know how to interact with other dogs and can be fearful or aggressive. Socialization is so, SO important to dogs who were taken away from their mothers at a young age. Good luck.

Thank you for the reply. I was thinking that it was too young myself. The puppy is already schedule to go to the vet tomorrow morning. I also have a female 15yo german shepard mix dog that seems to having a little maternial instinct towards the puppy so hopefully the will help the puppy out as well. As far as house training this puppy, I have been taking it really easy on it but it seems to somewhat grasp the idea already. Is it to early to try the house training approach for this young one?
Thanks for any advice.

8 weeks is the minumum age a baby should be taken from the mom and siblings. How sad for that pup. "Breeder" wasn't very careful.

I just want to say, that if the "owners" were looking to get rid of the pups and not taking good care of them (as obvious by letting them go at 4 wks) then thank you for taking on the task of raising this pup!  Though it might be more work for a while, it has been successfully done before.  Always remember to SOCIALIZE - there has even been some debate about early socialization before shots, since it's so important, even though there are health risks.  Since you have another dog that is a good start.  And good for going to the vet - they can probably steer you better about nutrition and how long they think you could wait before starting puppy classes.
 
ETA - Oh, as for housetraining - ask the vet about taking the pup outside a lot - you would need to take the pup out every 1/2 hour or so to try to limit accidents in the house, but I'm not sure at they age they can even hold it much.  I'm sure other members could help you more with this one, since I'm not too experienced with housetraining a pup, but I didn't want to ignore that part of your question. 
 
I also should have said welcome to the forum - we would love to see pictures of the pup!!  This is a really good resource and we hope you stick around!

We had to rescue a litter of pups at 4 weeks and about half had severe socialization problems (including my own darling Trim who now works far away from strangers and children at Charleston Air Force Base). Those pups also came from lines known to be somewhat unstable anyway, however.

Your pup is not absolutely doomed, but it is important that your pupper start meeting other dogs now and get as much contact with nice, stable canines as possible. Be very careful about only exposing him to dogs you know and are up to date on immunizations, but take advantage of as many of these opportunities as possible.

We definitely need pictures to accurately assess the situation. . . .[]

Yup, as the others have said, 4 weeks is WAY too young for a puppy to be away from its mom and littermates. A puppy needs to be with them until at least 8 weeks of age to learn proper skills like bite inhibition and how to interact with other dogs.

The best way for your puppy to learn those skills now is to have him around stable adult dogs. Female dogs especially are usually good about setting very clear boundaries and teaching puppies to respect them. Males can sometimes be a little too tolerant and that will only make for a very bratty puppy. [] Make sure any adults that you have your puppy around are vaccinated and have a very stable temperament. The last thing you need is to have the puppy bitten and traumatized during a very impressionable time period.

My advice is to enroll him in puppy classes as soon as he's old enough.  Put him in several if possible, and make sure these classes let the puppies play together.  I got my dog at six weeks, and I can tell the difference between her and other dogs.  She doesn't know what a growl mean for one nor does she really know how to play with other dogs except for playing chase.  You also need to teach him bite inhibition, so he knows when he bites too hard the game is over.  They don't realize how hard they bite, so this is extremely important.  What I did was yelp like a puppy if she bit me a little bit hard, I turned around and acted like she really hurt me and would avoid her for a little while and nursed my "wound" so it seemed like she really hurt me.  This way she knows if she bites hard the game's over.  It's worked for her, and I eventually started saying ouch instead of yelping so she knows what it's like with people too.

Thanks for all the replies. You guys gave me some good info, especially in regards to help control her biting force. As far as the socialization goes, I'm going to be dropping her off with my aunt on workdays so that she can play with her puppies(one of which actually came from the same litter as mine, we both took a pup). Here are some pics. Thanks again for all the replies.

I'd also like to add that in many places seperating a puppy from it's mother and litter at that age is illegal.

What a cute pup!!!
 
Sounds like you will be socializing him right away which is great. Good luck with the little one, enjoy every day as they don't stay little for long!

She's actually 5 weeks. Not much difference, but better.  Taking her to the vet today. Hope she like car rides better than our other dog.

I don't think most dogs like car rides at first, but if you take her to lots of fun places regularly in the car (not vet only), she'll grow to love it.

4 weeks is way too young.  The ideal age is 8 or 9 weeks, sometimes even 7.  By then they have had proper socialization and care.

It's not much, but yes, 5 weeks is better than 4.   You've gotten lots of good advice here, so I don't have much to add.  I've taken in rescue pups at 4 weeks and they turned out fine, but you really have to take the socialization part seriously.  Good luck to you!