Unusual bone cyst - amputation or surgery (x-ray attached)

Hello! We are seeking advice about our puppy. She is a Cavapoo, nearly 5 months old, and weighs 4.3kg. No issues with mobility, mood, appetite, etc. Three days ago, we noticed a sizable lump on her hind leg, just below the knee joint (it wasn't visible under the fur), and we are almost certain it must have appeared or grown to this size only recently. After today's x-ray, the vet admitted it's very unusual, and they sought a specialist opinion. Even though they think cancer is unlikely (although possible), we need to act fast. The two options are: 1. amputation; and 2. an additional CTC scan that would tell us if a surgery is feasible, and the surgery would be to remove the tumorous bone entirely, as the bigger bone looks unaffected. The surgery wouldn't guarantee later problems so the amputations seems a 'clearer' solution. Please see the attached x-rays (We believe the bone affected is a fibia bone) We are quite desperate to get some opinion since the case seems quite unusual. Has anyone seen anything like that? We worry about possible complications when trying to save the leg, and ending up cutting it off anyways. I feel it might be cruel for a dog, but still hesitant about using the easier option (amputation). Please help.

Hello!   I'm sorry that you are faced with such a harrowing choice.   If I've interpreted your post correctly (I am not the expert that your vets are here),  an amputation would leave you with a three legged dog, perhaps prone to arthritis in future.  A scan may show that nothing more can be done (and thereby leave you in the same place), but it might identify that one of those bones could be saved, in which case there is a possibility of a different operation.  If you choose this option, there is a level of uncertainty ahead (depending on: the success of the surgery, what the likely outcome of the surgery would be, what the risks might be).  Have the vets done anything like it before?  And at what stage (scan or analysis of bone after the op) you would be likely to get a definitive answer about keeping the leg / cancer.  Is arthritis less of a risk with the second option?  These are all great questions for your vet.  A question for yourself is, what will the costs and benefits of the more advanced surgery be for you?  I have met clients who have embraced scans and any advanced surgery they could be offered in similar situations.  I have also met clients who opted for amputation right away.  I have not judged either choice.  I'm not sure that there is a right or wrong answer (unless your surgeons find one); just two ways of making the best of a difficult situation.  For what it's worth, given the culture that I come from, I would be far more likely to opt for amputation because one operation later, I could expect to have a happy patient enjoying life again and a firm answer to the questions.  I have known many happy amputees in my time.  However, I chatted to a friend if mine, a better vet that me, who would almost certainly opt for the scan at this stage.  I wonder what your various vets would choose for their dogs?  Some decisions are not objective.  You know your animal; they cannot choose for themselves.  When there is no right or wrong choice, and you have looked at the situation from as many angles as you can, I think it makes sense to explore the option that resonates with you best.

Hello - how did you get on here?  For anyone else faced with this situation,I think a good question to ask directly of your vet would be, what is the best and worst outcome that could be expected from a further scan? They should write this in the notes and give you a copy for future reference.