Bless you for wanting to care for the little guy.  His life should be that of any four leg fur child.  I would have two concerns at this point, how does he use the stump? and long term joint care.  I mention the stump because it could be more of a hinderance than a help, and you may choose at some point to amputate.  And because of the odd gate of the three legs, there is a lot of stress on the joints.  There is a recent topic (this weekend) posted by Comet about her deformity (also front leg) and the resulting surgeries (rear legs).

Tripawds are the most amazing animals.  You will have a happy life with a tripawd in tow!

WOOHOO!  I'm the resident leg deformity expert!  I may even get my own forum, "Ask the Leg Deformity Expert" ! 

------

AWWW, Grizlee's mom!  What a wonderful thing you are doing!  You'll be so glad you are taking him!  I can't express the joy and love I have for my Comet because it's so deep.  I can already hear it in your writing how much that little guy is going to mean to you!  Well, just wait until he loves you back!  It's just the BESTEST feeling!  Your life will be so much more enriched!  I really think Comet has made me a better person over the years.  I believe I'm not as self-absorbed.  (some here, may disagree!)

Aside from what everyone here has said...

I would like to offer just a tiny warning about bringing your new baby into a new pack.   Be a little cautious at first with your other dogs.  Sometimes packs don't like lame dogs.  But since you have some naturally gentle-natured dogs, it probably won't even be an issue.  Plus, packs are more accepting of puppies anyway.  So, don't worry about.  I'm just offering up experience.  I wouldn't want you leave the little guy alone until you know for sure they are cool with a hoppity dog!  I had one dog, a boxer mix that didn't like Comet as a puppy. But I think it was more jealously since she was extremely close to me.  

Some dogs are even super protective of them.  I had an old chow that tried to keep the grumpy boxer mix dog away from Comet.  And then I had a shep mix (Rugby) that adored her and would get between her and people so no one would pet her (Comet is afraid of strangers, but that's because she came from a neglectful dog hoarder and was mistreated as a puppy!)

However, do not post puppy pics!  I will search you out and snatch your little guy!  (just kidding! I can't wait to see a pic and would love to see him grow!)  We have a lot of goldies on here that will become very attached!

Gerry is on Dasuquin to help keep his joints healthy for the years to come (he had his amputation due to injury in December and is about 2 years old). I heard about it first here as being a good supplement and found that Gerry's new vet recommended the very same when I just asked, without suggesting it myself, "Is there a supplement or something he could be on to protect his joints, given the extra stress of a missing leg?" Way to go, new vet!

Gerry loves the Dasuquin pills too. They're liver flavored and chewable – a piece of cake to get him to take.

Welcome to tripawds Grizlee and family!

Grizlee sounds just like my little Peggy!  The day she was born the breeder called me to see if we would take her, we have 2 other dogs from her and she knew we'd be the perfect family for lilttle Peg.  She's 7 months old now and the toughest fiestiest little thing ever.  However, she still can't go up stairs.  We've tried putting a treat on each stair, but she just won't go up. 

She beats up her brothers non stop!  The vet doesn't worry about her at all and she has no other health problems.  Her leg goes right to her elbow too.  She used it more when she was little, but as she's been growing she doesn't use it as much.  It just hangs.  She still holds toys and rawhides with her other paw.  She is a super fast runner.  When she's running you can't tell there's anything wrong.  When she walks you can tell though, she does the Peggy hop.  She's just a little angel and I love her so much.  I'll be happy to answer any other questions you have as it sounds we're in exactly the same situation. 

Here is a closeup of her sweet face.

And here she is with her brothers.