"Botched" amputation

[JenniferJSoprano]

Hello,
My husband and I adopted an 8 month old Italian greyhound/Pitbull mix (weird combo I know) with 3 legs. He had surgery 8 weeks ago, and we are told that the doctor that performed the surgery left in a bone that should have been removed. It looks like a 3 inch protrusion from his hip. Mistake or no, it does not appear to bother him in any way, and in fact I saw him use it to climb on the couch today.
The rescue tells us he needs a second surgery, which they will pay for, but my question is, why is it necessary? If it's causing no pain, and it's not urgent (we were told it's ok to wait a couple months) why do it at all? Here is a picture if it helps (Jackson is on the left) you can see the bump at the top of his hip where the bone is.
http://lh4.ggpht.com/_64Jp0276mow/SpA5xOA3YZI/AAAAAAAAHE8/MoZEU7GHe_4/s640/P8220033.JPG

[Kimberly Coyner, D.V.M., DACVD]

Actually, some surgeons prefer to leave a portion of the femur and pad it with the thigh muscle, for a little more coverage of the groin area. If you are concerned, then I would suggest getting a second opinion from a board certified veterinary surgeon, rather than the opinion of a rescue group, however well-meaning they may be, they are not veterinarians.
Kimberly Coyner, DVM.

[mrussakdvm]

That was great of you to adopt this guy...he is a handsome boy!.Most amputations of the rear leg are done at the hip joint and the bone you see would not be present. If it is not bothering him and there are no areas of inflammation/irritation you can watch it for now and see how he adapts. If it was my dog I would wait. There are always risks associated with surgery and I would not put him through another until I was sure.

[JenniferJSoprano]

Thanks so much for your answer. I do believe the rescue group has been in discussion with the Vet office over this, but I will most definitely get a second opinion. I'd rather not put him through another surgery if it is unnecessary - free or not.