At 9 weeks post op with our 70 ish pound 11.5 year old sled dog mix (Malamute x sighthound).  Regret? Only that we didn't know sooner and do it sooner so we might have gotten clean margins in the op.  His cancer was hard to detect - a nerve sheath tumor hidden in the arm pit of front leg and I think he had it a good 9 months prior to diagnosis.

I honestly didn't hesitate on the limb removal - I viewed it as a medical necessity.  Not saying I wasn't shell shocked and I didn't grieve at all at him losing a leg.  

Pofi did, I need to be honest, have an easier and smoother recovery than some, but I was as prepared as I could be for it to be harder.  My advice, should you decide to amputate,is that pain meds are necessary - not a luxury.  My vets, regular and specialists, were all in agreement, pain is serving no purpose once cancer has been detected and post amputation.  We know what was wrong - we don't need pain as an indicator. So we managed deliberately and with premeditation.  We started off strong with pain meds pre and post op and tapered down gradually.  And with all three modalities - Tramadol for pain receptors in the brain, Rimadyl for anti-inflammation, and Gabapentin for nerve pain including the potential of phantom limb pain.  

Best thoughts!