Took Rhubarb, my 4 yr old toller, to the vets last week as we noticed he'd suddenly developed a large lump (golf ball size) within his sheath, they gave him an antibiotic jab and removed it the next day. Just got the results back and its a mast cell tumour-poorly defined, which sounds like its about as bad as it can get. He's being referred to an oncologist, Tom Cave in Somerset, where I am. They will see if its spread and see if hes suitable for chemotherapy. Does anyone have any advice or experience of this? Have googled and it doesn't look good. Hes insured up to £4k thankfully, but I don't want to put him through chemo if the prognosis is bad. Any tips on the sort of questions I should be asking when we see the oncologist and any experience of chemo in dogs. I'm so worried about my Rhub, hes such a lovely kind softy of a dog, great with the dc's (6yr dd and 5mth ds). He has got a bit thin lately and doesn't have the same energy he used to when chasing a ball, his legs start to tremble and he gets breathless, does this mean its already spread? He's only 4. poor love.