I am so sorry to hear this about Milo. I know what you must be going through and you will need a bit of time to think and come to terms with this awful diagnosis and dilemma. I don't think the prognosis for this awful disease has a satisfactory outcome for very long.
I had to make the same decision for both of my last two flatcoats. Both were diagnosed with the same thing within 15 months of each other.
It is very distressing thing for you to go through. I will tell you my experience of this so that it may help you decide what to do.
I decided I couldn't put either of them through amputation and recovery for the sake of only a few month's more time with me. They were both such active dogs.
Zac, my male went onto pain relief and coped for a little while after being diagnosed, but we ended up having to take him to the vet as an emergency in the middle of the night. His pain just got on top of him and we could no longer control it for him. I ddon't usually pray, but I prayed for his release at the end.
When Luna was diagnosed with the same thing a few months later, I decided I could not put her through either an amputation or the alternative and asked that she was immediately put to sleep. She didn't come out of the anaesthetic from the X-Ray. She never knew a thing about it, which, after the shock, was quite a blessing. I still feel guilty about poor old Zac; in hindsight I should have done the same for him, but I just didn't know how it would be for him.
Sorry for such a depressing post. It is not my intention to make things worse for you and I wasn't sure whether I should say anything or not, but I do hope sharing my experience with my two dog's situation is of some use. Ask your vet to give you a straightforward, honest opinion and be guided by what he/she tells you.
For what it's worth my thoughts are with you.

Just a practical point but is there anyone who can go with you to the vets next time you have to see them?

When your emotions are so involved it's hard to grasp exactly what they are saying. I was so glad Jamie was with me when we found out about Cherry possible having a nasal tumour as much of what the vet said went right over my head as my mind was in such a turmoil.

I'm so sorry to hear this really sad news

Poor Milo Thinking of you both xx

I'm sorry to hear this

Ime as long as the cancer hasn't spread to the chest chemo and amputation in an otherwise slim and fit dog gives them a good quality of life,dogs (and cats)do not seem to suffer with the same chemo effects we do and also adjust to the amputation very quickly.....if u go down the route of amputation it should be asap...an x ray of chest under the same ga and if clear straight to surgery....bone cancers are very agressive and painful

Good luck with whatever u choose xx

Good luck in whatever you decide, only you know what is best for your dog and your particular circumstances.

Hi...i was really sorry reading your post and just wanted to say that I have a dog who last year had to have his front leg amputated aged 9 years, he had developed a tumour between his upper elbow and shoulder, when we first took him to the vets we were told by one of the vets that the tumour could be removed but couldn't guarantee that it wouldn't return, so we had the fast growing lump removed over 2 years ago, it returned with a vengeance at an alarming rate and we had no alternative but to consider amputation, it was a terrible decision to take but the options were that it would cripple our little dog and even grow into his chest area endangering his life , we were all terribly upset and in the end had it done...now the good news is that the recovery period and how they cope is amazing and i was and am so proud of his efforts to get back to normal again.....I am not comparing my dog in any way as i can see you have the awful dilemna of chemo to consider as well but as one of the post states that the chemo in pets isn't as debillitating as in humans although i have no experience of this luckily, but i just wanted to offer some advice on the amputation side of things...it is a devastating but not the end of the world.. i really hope all goes well for you all...take care

Thank you taking the trouble to post and I need to hear experiences from all sides to help me decide what's best for Milo. My head tells me that it would be kinder to have him pts straight away but my heart wants to keep him for as long as I can, partly so I can get used to the idea - is that selfish of me? I don't know, it's so difficult to think straight about something so emotive.

Oh you poor thing. The last thing you are is selfish. I would bet that Milo wants to stay with you for as long as possible too. You love him enough to not let him suffer unduly, and if he wants to fight on, then you can too. But when it's time, you'll know...don't beat yourself up too much.

Now, this easy to say, but really hard to do: try to be more like a dog and live in the present. Make the most of every precious hour you've got with him....focus on him here and now and don't get overwhelmed by how it's going to end.

I really feel for you.

Thank you.xx

No Pam you are not selfish, far from it - it is an awful dilemma to be in and your emotions are perfectly normal.
As Girondeb says dogs do live in the here and now. Perhaps you can try to do something similar. When you can think a bit straighter, which will happen after a little while, go and speak again with the vet - sometimes vets are not sure how much information to give when first they need to tell owners of a serious diagnosis. If you ask directly I believe skilled and sympathetic vets can guide you into deciding what is best for Milo and you. Go with a list of questions - "what ifs" - and take your time. If possible, take somebody close to go with you and go without Milo.
Nobody can tell you the route to take with these sort of decisions, but you will know yourself what is best for Milo once your head clears and when you give yourself a bit of time to think.
Kind regards. Rena