Hi @milosmommy, welcome. Your future posts won't need to wait for approval so post away! Are you in the UK? Just curious, because of the time you posted (way early here!).

Generally, how much of the leg that gets taken is a matter of the vet's preference, and also the health condition/diagnosis. Some vets will do a partial amputation because it's what they learned in school and it's easier for them. Some believe leaving more leg helps with balance. And if a pet has a limb cancer, the tumor location can also determine how much or little of the leg is taken.

Either way, partial amputations have pros and cons.

The cons: a partial amputation can present some wound healing issues, because the skin is so thin around the bony area. I hope you won't need to go there though! How is the area healing? 

The pros: Many vets believe more stump helps with balance and adds cushion. Also, if a client has a prosthesis in mind for their dog, it's imperative to leave as much of the leg as possible. But it sounds like this wasn't something you talked to your vet about? If not, you may want to have your dog evaluated by an orthopedic surgeon to see if he's a good candidate for a prosthetic leg. That would be a real bonus if you are able to invest in the time and cost of prosthetic training. 

If it's any comfort, you aren't the only one whose dog has gone through a partial amputation. See this article for examples:

Partial vs. Full Leg Amputation for Dogs and Cats, What’s Better?

Oh, what's your dog's name?