Hi and welcome to our family 🌺

I am really sorry you find yourself here but  rest assure we are all here for you and we all know first hand what you're going through. 

When my baby girl was diagnosed with osteosarcoma (clear lungs) these options were discussed:

Amputation - this is the only way to remove 100% of pain, no drug works fully for this kind of pain. 

Limb sparing surgery - there are several procedures but oncologist said it would not be a perfect choice because of infection risks (high) and the fact recovery takes many months. In the end, if there were serious problems, we would have to amputate. (Meg and Clare "megstamom" went for limb sparing surgery followed by amputation so you might want to chat with her if you'd consider going for limb sparing surgery)

Radiotherapy - in this case, there is a maximum amount of sessions our dogs can have, it targets the tumour directly and reduces the pain dramatically but requires general anaesthesia each time. Also, as the tumours are targeted, so is the bone so the risk of a pathological fracture increases (fracture which never heals) If a fracture occurs, amputation is needed.

Amputation plus chemotherapy - this is statistically the best option (and the one I went for)

Carboplatin - generally this is the first option and 4 to 6 sessions are done. Cerenia is also used, normally the day of chemo and for about 3 days after, to prevent nausea.

Doxorubicin - this is the second choice chemo, as it is dangerous to the kidneys and heart. A maximum of 5 sessions can be done. 

Later on, Eurydice also did:

Metronomic therapy - generally this is used after the IV chemo. It is administered orally and is combined with an anti-inflammatory and an antibiotic. The aim is to try and act inside the blood vessels and by doing so, starving the tumours of the blood supply they need to grow. 

Others who could not have amputation (like Hazel, the Great Dane) also had:

Bisphosphonates - this is a treatment by which the tumour is "enveloped" and therefore makes it more difficult for it to grow. It is normally used only if amputation is not possible.

There is a lot to consider, I know, but I can promise you once you make a decision and move forward you will feel better. 

Also, losing a back leg is much better than loosing a front one as the vast majority of weight is carried by the front legs. 

Please try not to be scared, we can all promise you here dogs can do fabulously well on 3 legs and have a wonderfully happy life! 

And as for life expectancy, remember statistics are worth what they are worth, we have many, many, many cases here of dogs who largely passed the forecasted "deadline".

Do let us know how you're doing, we're all here for you!

Sending you a hug and cuddles to your baby boy 😘😘😘🐮💫✨🌟🌹