Hey Bagpuss, sorry to hear about this mate. If it's of any reassurance, I went through a similar situation last year with my dog and wrote about it on the Hamilton Project forum, although the tangent I went off on may not be much practical use to you:
Now it gets a bit more strange, or at least what could be interpreted to be 'strange'[1]. My dog got a 20cm stick stuck between his oesophagus and carotid artery which, according to the vets who treated him, usually results in death. When I realized that he had something stuck in his neck (another bit of potential weirdness is that I "knew" what was wrong with him and what would happen next with absolute confidence) I immediately started doing the same sort of 4th jhana/intent/healing stuff I mentioned already with that same certainty of intent that it would work. I can't explain what this actually felt like but it was definitely NOT an affective feeling, which complicates things further, I know, but is worth mentioning. The best example I can give is that I could "see" it without any mental visualization occurring, it happened in that instant as if it was being shown on some panoramic television but I need to emphasize the fact that there was nothing imagination-based, nothing visualized, nothing being experienced in the way that you can, quite literally, imagine but it's exactly the same thing as I've experienced when doing magick successfully but I've never had this, what I can only call, detached coolness which is different to equanimity so easily. What happened in the upcoming days gets a bit more peculiar, the dog was taken into vet hospital and my partner was distraught but I remained calm and relaxed, quietly knowing that everything would be fine and that, even if it wasn't, everything would be fine anyway but not mentioning anything to anyone about what I was doing.
Roll on to last Friday, we were supposed to get the dog home but they called to say he'd developed an abscess on the wound on his chest. I got one of his hairs are decided I would try to take on the infection. Sounds weird, I know, but humour me here 'cause even I don't believe a word of it yet. I'm trying to present exactly what happened with as much detail as possible because I'm not 100% certain that any of this had anything to do with magick but I thought it'd be worth mentioning, if only for a laugh at a funny story with a happy ending. Within four hours, the previously scabbed up wound beneath my ear began to bleed, and apologies for the graphic descriptions here, this foul pus coming from it and fresh blood, not dried up, de-oxygenated blood from a dormant wound. As I cleaned it, the sebaceous cyst which caused the abscess in the first place burst into the wound and I ended up spending the rest of Friday and Saturday morning with this horrible mess coming from my face, my hand pressed against my jaw which was painful and seemed to be developing an infection. Obviously infection following a cyst bursting is fairly normal so I don't place much importance on that, just to clarify.
We went to get the dog around 1300 and spoke to the vet. Again, the word "miraculous" came up a few times and the guy mentioned how quickly the abscess had cleared so we brought him home, the dog, not the vet, and I went for a sleep 'cause I'd been up since about 0445. That night, the wound dried up again and over the last few days it's gone from being infected to being scabby again without antibiotics. I want to emphasize that I'm not trying to say "Look, I used magick and did some healing stuff", it's just a few interesting things which I thought were worth mentioning and which may be food for thought. I'm not entirely convinced yet that I'm not just selectively remembering this, deleting parts or doing any of the automatic editing stuff the mind does with memories and intent, but I'm inclined towards accepting it just purely because it's as cool as fuck and makes for a good story. No big deal anyway, there's more important stuff to be done and I'm just happy that my dog is back home, safe and well.
The main thing about doing all that which helped me was to just know, without a doubt, that whatever happens will happen regardless of what you do. I just tried to make the best of an unfortunate situation, not exactly sage advice or anything but in realistic terms you just need to go with flow and deal with it as it happens. Know too that any anxiety, stress or worry you have is never happening right now in this moment, it's always related to something that's either happened already, or not happened at all, and can only even occur as an afterthought to any immediate sensate experience. Go with metta and, in my opinion, bare sensate awareness as difficult periods like this are incredible opportunities to look at attachment, craving, beliefs, and anything preventing you from clearly seeing how things actually are right now.
I really do hope that your dog recovers well and that you and your family are bearing up ok, take care of yourself and let us know how she gets on. Metta to you all wherever you are.

[1] Not normal; odd, unusual, surprising, out of the ordinary.
"He thought it strange that his girlfriend wore a Ronald McDonald mask while they had sex."