Operation for my dog

Our dog that has been with us for nearly 3 years needs an operation on his right leg,he has a problem with his bones,maybe then can save his life with the needed operation,they might have to cut his leg off and put a prosthetic one or maybe they just needs to cut out some bits and fill in the bones and we don't have that much money to do any of that and we love him so much,we are a family of 8 people and he's our family too and we love him and don't want to let go of him just now,but if he doesn't get the operation he needs we are going to have to put him to sleep and say goodbye forever and he loves us so much and he greets us every day we get home,even if we've been gone for 2 min he still acts like it's the first time seeing us,he's full of joy and life and we would do anything for him,just for him to live a little longer,he's our ever first dog(his a leonberger breed) and he's so special to us,we would be so grateful if someone would help and make his life a little longer,any amount would help us.Thank you so much if you help us