We called the emergency vet, they had us induce vomiting, and then had us bring her in. I was holding it together until then, but when the vet started talking about how they couldn't know for certain whether she'd gotten a dangerous dose or not, I started losing it. They said they had to keep her overnight, and treat her with IV fluids and some medicine that treats the toxic effects on her liver. If all goes well, the course of treatment will be over sometime late tonight or early tomorrow morning. (I wasn't clear on that.) We came home and pretty much bawled the rest of the evening. Kev stayed calmer than me, but not by so much.
Here's details on acetominophen toxicity in dogs, including all the terrifying symptoms. Even if she didn't get a fatal dose, she may suffer long-term liver damage. Please note for those with pets -- Tylenol is apparently much more dangerous for cats, with a small dose (just one pill) likely to be immediately fatal. Cats, I imagine, are less likely to shred open a fairly tough plastic container, but either cats or dogs will happily swallow pills left where they can reach them.
Ellie seemed to be breathing sort of funny while we were there, but that may have just been anxiety on her part because we were acting weird, or frustration that there were all these other dogs and we weren't letting her out to play with them. The breathing calmed down before we left. I called them last night, and again this morning. So far, Ellie's okay; they say she's been very calm, no symptoms, just lying there looking bored. That page says it can take up to twelve hours for first-stage symptoms to develop, so I'm hopeful that if she's okay now, she didn't get a dangerous dose. I'm calmer this morning, though still anxious. I want her home.
It's going to be a long day.
I feel like such an idiot, not picking up that bottle and moving it out of reach. I did think about doing that, a couple of times, but it was on the other side of the room, and we were all there, and I didn't think Ellie would be likely to get to it. I didn't realize that a tiny bottle like that could actually kill her, even though I know Kevin has told me before that Tylenol is really bad for dogs. I am going to be a terrible mother. Kevin says I just have to learn to pay more attention to this kind of thing, to small risks that might have severe consequences. I don't know.