Dr. Mike called back this evening. The good news is that we really did everything we could have (and then some), and that nothing we could have done would have changed the outcome. She did not have a blockage, so surgery wouldn't have helped. She didn't eat anything toxic as her kidneys were fine. Her liver, however, was bad. He said it was very large, engorged with blood, damaged badly, and had a clot on it. There was also a small amount of blood in her abdomen - not a lot, but more than would be expected. He wasn't sure how her liver became so damaged. He suggested perhaps she was exposed to something viral (though her sister is still healthy - knock on wood), or more likely a bad reaction to the vaccination she got the day before she started to swell up.
I've always been aware of animals being able to have allergic responses to vaccinations, but I always imagined it to be more like an immediate anaphylactic response. I did not know that a vaccination could attack organs and kill slowly, and though it is exceptionally rare, it does happen. I waited until the kittens were ten weeks old to vaccinate due to their size, and it just wasn't good enough. I take full responsibility for that choice. Now I'm left wondering - what is more important - vaccinating Floki, or assuring she doesn't die the way Lagertha did?
Floki is set to go back for a second booster in two weeks. She's still nursing on Mabel and is just a hair above one pound right now. I'm not sure if I will go through with it or not. I think it bares more research and questioning. Our city does not have a license requirement for cats, and though they are supposed to have rabies vaccinations, I wonder if we could get an exemption from the vet due to Lagertha's bad reaction.