Everyone else has said everything I wanted to say, but I just wanted to add my support too. You are most definitely not a selfish or irresponsible owner. I have been in the same situation as you, with a greyhound the same age, and I made the decision not to amputate or do chemo. I researched it all very carefully and then decided it wasn't right for us although I have the utmost respect for all those who do choose that route. Amputation is a very painful operation and chemo is not without it's complications and the chances are high that it would only buy Abbey a few more months at most. You have to trust your gut instincts and try not to second-guess yourself. You are in a horrible situation and you would probably feel guilty whatever decision you make.