My 8 year old Beagle, Barney last year developed a hug lump near his shoulder which we were told by the vet was fatty tissue and something Beagles seem to suffer from. Rather than take this as gospel, we took Barney to Sydney University which has possibly the best facilties in Australia for a MRI $900, Biopsy $450 and the operation which cost $2500.
I guess what I am trying to say is, always get a 2nd opinion when they start showing signs of lumps and bumps particularly around the joints.
Fortunately for us, we didnt have to get his leg amputated and hes healthy happy and wildly eating as normal.
Sassy had one of both sides of her neck. I was told by the vet I was taking her to, there is a way to figure out if the lumps are cancerous or not. If you can grab the lump and move it around, it isn't cancerous. He said the cancerous lumps literally have 'roots' and will not move. If you try to move them, it will take some strength and will cause the dog discomfort. I'm not sure if this is 100% correct, but I trusted my vet, and they never bothered her, so I left them alone. My mother's pitbull ended up dying of a large cancerous mass they operated once, and it came back, but worse), and after seeing her lump vs. my beagles lumps, there is a difference, so he might be right.
Oh believe me, I learned this the hard way, not with a beagle but another dog. The vet kept saying it wasn't risky, that it was fatty tissue etc. Well, my dog almost died from that; he needed rush surgery. That was another story altogether. Get those lumps and bumps checked not once, but twice, by different vets, I don't care how much you trust them.
Any lump needs to be evaluated. It should be aspirated and the fluid analyzed. This is the only way to tell what it truly is. In the defense of the Vet-those soft lumps are "usually" fatty tumors. But-----I would always push for a more clear diagnosis, one with diagnostics beyond just feeling the lump.