My girl is 13 and a half years old. She has had a tumour in her mouth for a couple of years.
It was biopsied and debulked twice and they couldn't identify it, in fact they said they'd never seen anything like it, but could say from their analysis it was cancerous, but only of low malignancy and likely to be locally invasive, rather than metastasize.
It was also slow growing, but despite having a soft tissue component on the surface was calciferous and bony, which meant removing just the lump wasn't an option. If fact the vet said they struggled to get enough off it off to biopsy as it was so hard. To remove it would have meant her undergoing a hemi-mandibulectomy and knowing our girl as we do, taking into account her age, the fact that she is partially deaf and blind and going on past experience of her having surgery and not coping with it terribly well, we felt we could not put her through such a major op.
Until recently she has been happy enough in herself, eating well, despite the growth being in a fairly obstructive position around her left lower canine. She has been active enough for a dog of her age an carrying a nice amount of weight etc. In fact the only problem has been that her mouth smells truly awful. We have to give her a dental wash daily to try and keep it under control, but it really is the most awful thing I have ever smelled, not helped by her favourite position being under the kitchen table (not good at mealtimes at all).
After having three different opinions from various vets on how we should proceed, ranging from going for the hemi to debulking and partial jaw reduction, I took her to see a fantastic local vet who talked through all the options with me, left me to think about it for 48 hours and then discussed how to proceed.
We took the decision to give her palliative care only, for all the reasons stated earlier and he agreed that in his opinion this was probably the kindest course of action. At the time she wasn't in need of any medication, didn't seem to be in pain apart from slight stiffness in her back legs and was a happy content girl. She has needed antibiotics a couple of times when the growth has got cuaght/nicked by something and become infected, but other than that she hasn't required any treatment.
We are now a few months down the line and she is deteriorating fast. The growth has started to grow rapidly and in the last two months has gone from being half way across to encompassing all the teeth across the front of her lower jaw. Despite this, she is still managing to eat her normal amount of food, albeit a little slower than she used to.
BUT she is losing weight, despite eating the same amount and exercising less. She has also developed dark patches on her skin, which I recognise from when my own father had end stage terminal cancer. I think her eyesight has worsened, as she panics when she doesn't know where she is, so no longer enjoys going for a walk and instead prefers to pootle around the garden a few times a day. Some days she is very reluctant to get out of her bed and we have to carry her outside or she will just wee in her basket rather than going outside.
I think she may have suffered a mild stroke recently as well, as she seems unbalanced and to lean and turn to the left as she walks and she seems to spend periods of time just sitting with her head hung sort of swaying slightly, as if she's not quite 'there' iyswim. Occasionally she seems to get shivery as well. 
The other day when she came in from the garden, she came through the doorway, turned as she did so and walked straight into the door, then walked left again straight into the downstairs toilet where she ended up stuck between the toilet and the wall repeatedly walking forwards into the wall.
She isn't like this all the time though, just odd episodes. The rest of the time, she still seems fairly content, still eats all her food etc. That said, the episodes are becoming more and more frequent.
I really don't know what to do. I'm taking her to the vets this week, as at the very least I think she needs some pain relief for her joints and I want to be sure she isn't in any pain, but I'm thinking the vet might suggest we pts.
Thing is, it just doesn't feel right. I have had dogs for over 20 years and have always 'known' when the time was right iykwim, but with her it just doesn't feel right at all.
I am so confused. I really don't want her to suffer, but I can't get rid of this pit of the stomach feeling that to let her go now would be wrong. Obviously I am hoping they will be able to offer her some palliative treatment to make her more comfortable, but if they do suggest pts, I'm afraid I won't know what to say.
Why am I finding this so confusing? I have had to make this decision many times before and have always felt it was the right thing to do. Why can't I do it this time?