Lump on front right ankle of 12 y/o mixed breed

Hello, I hope I can find some help here. My dog is a 12 y/o small mixed breed (our vet thinks Jack Russell, Sheepdog mix) who a few months ago developed a lump on the outside of his right front ankle. It is kind of hard to touch but still is a little squishy, almost like a harder paw pad feeling. It also seems to be movable if I wiggle it around. Pre-existing conditions/procedures include: colitis since he was a puppy (he is on special food for it), and he’s had both cruciate ligaments in his hind legs done. He was checked a little under a year and a half ago for other lumps (turns out they were lipomas) while he was getting his second cruciate surgery, as he was already going to be under anaesthetic. Our vet also suspects he has arthritis, but nothing serious enough to warrant treatment. He doesn’t seem to be in pain with it, and still has his appetite and happy disposition, but considering his age and the location of it from my research I am afraid it might be osteosarcoma. However it is also the leg that he has always folded under him when he was lying down, and I do know some dogs develop lumps from pressure points. Or it could be another one of the lipomas he has delveloped, or something else entirely. My parents don’t want to investigate this further considering his age and lack of behavioural changes. They want to avoid putting undue stress on him (which I agree with) but also don’t want to know if it is something sinister or not. They have also said that if it is cancer, that opening it up for a biopsy and exposing it to air can make it spread quicker (don’t know if there’s actual theory behind that?) and that he is too old to be put under anaesthetic just for this keeping the risks in mind. They have told me the ultimate decision to get it checked out is up to me, but I’m not 100% sure what I want to do. It could be nothing, but it could be something. This dog is my life, and I worry about everything with him. Any professional advice would be great, thank you.

Hello - and what a dilemma.  A common one, but that makes it no less stressful.   I think that you've had lots of advice already.  What you need is some help unravelling the decision, because the ideal answer might no exist, and you can argue all day.  I agree with your vets that it is nigh on impossible - in fact, it IS impossible - to guarentee the substance of a lump from the outside.  I agree with your parents that biopsy can spread the substance of the lump around, or can encourage it to multiply more or in different directions, even if the way they described it wasn't the most scientific.  However, without sampling the lump, it isnt easy to know what it is.  Fine needle aspirates (putting a needle in and stealing some cells) sometimes get too few cells, or cells that arent actually representative of the bulk of the lump. So:  what to do?

I'm afraid that you have to accept that there is risk with all of these methods - risk that is not necessarily under your control.   There is no RIGHT decision - take three twelve year old dogs with lumps on their ankles and the best answer might be different for all of them.    If you type 'lump' into the search bar on the blog, you can find me wittering more about this.

As far as I see it, you can leave the lump be.  But if it is cancer then it will continue to grow until it causes problems.   Or you can biopsy - and find out what it is.  What are you going to do if you find out?   - would you consider chemotherapy or full removal of the lump if it was cancer?  If so, then this is fully worth doing.  You mention osteosarcoma - bone cancer.  Does your vet think it might be that?  Osteosarcoma can often be seem on x-ray and amputation or chemo is often reccommended to extend life.  Again, would you want this if you knew?

So, to summarise;  there are a lot of unknowns here.  Biopsy would help to reduce them and may change the outcome.  There is, however a risk - and a cost - to biopsy and of any subsequent treatment.  The patient is 12 years old, which means that any intervention is unlikely to buy 8 years of good quality life.  This is, however, a decision that facts can only inform so far.  Largely it is made on gut - and like most gut decisions, sometimes we go away regretting them.    A good question for your vet is 'What do you think you would do, if he were your dog?'

The reason that I have, in general, biopsied lumps is because if a lump is cancer, then it might then be treated correctly to maximise longevity (which it couldnt be if I didnt know what it was) and for many lumps / dogs this benefit may far outweigh the risk anaesthesia or of cutting into the lump.   However if I had no intention of treating the lump for example, I would not biopsy.

Furthmore, for many 12-year old dogs anaesthesia carries quite a high risk (is that the case here?) or there are other issues muddying the water.   There is absolutely no right or wrong answer but its important to try to ask lots of questions and work out a good answer for you.