URGENT DECISION - Possible Osteosarcoma Dog

Hello everyone and thank you for taking the time to read this. I will explain everything in the best way possible. Let's start from the beginning. I noticed that Dagast (my dog, a 9 years old Czechoslovakian Wolfdog) in November was limping when standing up from resting on the couch. The limping lasted about 15-20 seconds and then he started walking normally again. At the beginning I was thinking that he had injured himself in the garden so I waited. But then at the end of November we noticed a lump in his left back leg, so early December I brough Dagast to the vets where I live. They thought it was a mini-fracture and gave us pain killers and an anti-inflammatory, saying that if the problem persisted in January then we should have brough our pup back for another check. We brough Dagast back to the vets last week as the issue is not resolved, we did an x-ray and a biopsy. Unfortunately from what the vet could see in the x-ray it does look like a bone tumor so she used a fine needle to take a sample for the biospy. What she did not understand is that Dagast is not feeling pain at all, he still limps a bit when he stands up but that's it, we walk, he eats, he is exactly the same dog as always. Today the biospy came back inconclusive as they could not determine if the mass is indeed a bone cancer or not, giving us 2 options. Option 1: we do a bone biopsy which could take up to 2-3 weeks due to the decalcification process involved and a CT scan. This to understand what we are dealing with and take the best course of action. Option 2: we take off the limb completely to avoid any spread of the cancer (at the moment Dagast's lungs appear to be clean) and then a round of chemiotherapy to destroy the cells that might be in the process of spreading or have already spread but too little for the xray to detect.   This isn't a easy decision at all as you all can imagine so I am asking your opinion to see if I can clear mi mind and take an informed decision. I want the best for him and I am prone to take the safest option and proceed with the amputation. If it is indeed a bone cancer there's no time to waste and we need to act quickly, I was relying on the biospy to rule out some options but unfortunately as written above it was unconclusive. Waiting other 3 weeks might be too late? I really don't know how to deal with this.   I have attached here the 2 xrays that the vet kindly sent me, can you give me your opinion please? I know without a biospy there's no way we can asses if it's an osteosarcoma or a less aggressive bone tumor, but for what I see, it does look like a bone tumor.   Please let me know what you think. Much appreciated and thank you in advance. Sam & Dagast  

Hello - to my opinion, I think you have answered all your own questions and the main point is that you do not like the answers - and Im not surprised, because that sounds very frustrating.  I were to say 'Oh yes that's definitely cancer' or 'No theres no way that's cancer,' could you trust me?  You shouldn't.  I am just some vet with a phone in my hand, looking at a picture of a radiograph of an animal I have never seen;  your vet has seen the patient and the radiograph and sent a biopsy away, but still hasnt a definite conclusion.  Unfortunately, osteosarcoma and osteomyelitis can look very similar to one another;  cannon-ball lumps in the lung fields would tend to support a diagnosis of osteosarcoma, so your vet sounds to be justified in radiographing the chest and taking a biopsy.   Im sure that they are as frustrated as you are at this point. Good questions for them include:  would it help to call the pathologist or medical specialist up.and run the details of the case by them?   - in my experience pathologists (who usually see a sample in a pot) like to talk about real life cases and are very supportive. Another good question is:  'what would you do if this was your dog?'   Most vets will have an opinion. Lameness is a sign of pain; you walk funny because it hurts to put the leg down normally. Wishing you the best of luck- there may not be right or wrong answers here.  Please do let us know what happens next