Thanks to both of you. Once again, I'm so glad this site is here and thankful to have this kind of support. 

I had to re-read the email from the vet - we'd have to finish 3 rounds of the carbo and then do the surgery. He is scheduled for 6 full rounds of carbo, so it would technically be halfway through. He'd finish his third round, then we'd wait 2-3 weeks, check his wbc and do surgery if that was ok. I'm organizing a consult with the surgeon there in addition to the oncologist, because I want them to determine how invasive the surgery is going to be, how much it will affect his mobility, and what kind of recovery period we'd be looking at before he could resume and finish the chemo. With respect to the lump itself, there is a chance that it is a soft tissue sarcoma, which is much less aggressive than osteosarcoma, but osteo simply can't be ruled out until the biopsy, and the biopsy wouldn't happen until we remove the lump and send it in. So we are in a catch-22. Can't even really find out what it is until after 3 rounds of carbo at the earliest, and finding out what it is will involve halting the chemo that he needs so badly to stop the spread of the osteo. 

The goal, of course, is Mosby's happiness and comfort. So whatever is thrown in our way, that goal will underlie all decisions that we make. And now that he's got his sutures out and is well on his way to physical recovery we are going to start introducing some low stress, low activity trips out of the house (besides his daily trip to get the mail, which he loves), because I know he's bored, and mixing some fun in with his healing rest periods will be good for his doggie soul. 

Thanks, I will try to look for her blog. It does sound like it would be helpful. 

I believe the rationale for no doing chemo now is that the "emergency" situation, as it were, is to address micro metastasis of the osteosarcoma, so that has begun, and generally you don't due surgery during chemo because the immune system is down. So while the lump needs to be removed, I think that the vet wants to at the very least get through three good rounds of carbo (which would be 1/2 way through our doses), check his wbc and platelets, then operate while keeping him on antibiotics to be safe. There is an option to monitor it through the course of 6 treatments and then decided on surgery, but then we'd be facing an unknown for several months. 

Where was the site of Heffalump's (cute!) second tumor, out of curiosity. Our oncologist is also fairly certain that it's soft tissue sarcoma, rather than osteosarcoma, but of course that's my biggest fear, especially since he had osteo in the other leg. This lump isn't in a bone or joint proper, like it was in his other leg (at the knee joint) - it's a subcutaneous, somewhat movable lump on his left thigh, maybe a quarter in size, over the thigh muscle. I know that extraskeletal osteosarcoma is possible, if rare, and the fact that he already has osteo is what is making me stress about it. I am reminding myself that we won't have a definitely diagnosis until it's removed, so I should try to worry as little as possible. Nothing we can do now is going to change anything. 

Go Heffalump beating the odds!

Sally, I'm not sure what I would do without your kind, encouraging words. It makes sense that three treatments can be effective - that must be a point at which they feel comfortable stopping for a bit. We will just hope that his numbers and everything come back strong after the 3rd treatment so he can proceed with the surgery. That's awesome about Big Lou, and very encouraging to hear. 

It's also encouraging to hear about Izzy's operation while on chemo. Our oncologist specifically mentioned that she'd have Mosby on antibiotics through the surgery process, so it sounds like they would treat it similarly. I'm not sure if carbo will do double duty for Mosby, might depend on the type of sarcoma, but it probably won't hurt. 

Thanks everyone. Mosby had another good day today. He seems to be handling the carbo well (or at least the meds are helping him handle the carbo well) and has definitely not lost his appetite! And don't worry about the "less healthy" treats, Mosby definitely gets those, we just try to keep the majority healthy since it seems like we feed him so many and we want to keep him slim and trim. 🙂 Yesterday we made pasta and he got some pasta - that's his absolute favorite because he takes after his mama and loves carbs. 😉 And it's Saturday night, so he'll be getting Frosty Paws tonight! He loves his Frosty Paws. He's a rotten beggar, and his habits are definitely returning. 🙂