First I’m very sorry about your dog.
I don’t know as much of the veterinary world. And there’s a ton of information your vet and surgeon has on your specific case that no one online will have, so no one here is going to give you very specific answers to your case. So take everything that follows with a grain of salt, and talk more with your surgeon, not internet strangers. And it sounds like your dog was in a very dangerous situation, keep in mind a bad outcome doesn’t necessarily mean anyone did anything wrong, you and your surgeon included. I can tell you some general things about how repurfusion can be dangerous in humans though.
I was confused why both your explanations are hung up on free radicals. Not that there aren’t, I’m guessing there’d be more than usual. It’s just a bizarre explanation of repurfusion injury. There’s many dangers, but basically if you have dead or poorly perfused tissue (sounds like there was a lot of this from your description), and there’s a turniket or a hernia acting as a turniket in this case squeezing the blood supply so nothing is getting in or out, or very little is getting in or out, all of the harmful dead stuff from the process of that tissue dying is somewhat stuck there. But once this narrowing is resolved (taking off a turniket or getting the tissue out of the henria in this case) now there’s blood flow and all the material form this dying or dead tissue has a clear route back to the rest of the body. It also sound like in this case there was a really horrific large hernia with probably multiple sections of multiple organs that had already infarcted (died from lack of oxygen/blood flow) based on what you wrote. Sometimes in humans you can resect small portions of dead intestine and reconnect remaining pieces, but you can’t just take out their whole liver, they need that.
But free radicals is a weird red herring thing to talk about. Potassium is the main killer for repurfusion injury. There’s very little potassium outside cells (like in your blood and fluids), but tons inside cells. Well we have a whole mass of tissue from multiple organs that just died and that’s all getting released at once. The heart does not like this, and can go into arrhythmias and stop beating. Potassium is actually the final drug used in a lethal injection in capital punishment for instance. There’s tons of other harmful things going on too. But if large sections of multiple orgams had already died or been severely injured by the hernia, there may not have been any possible way to save them. And if you leave them that way the harmful stuff will find it’s way out eventually anyways, and the dead gi organs will cause massive septic shock as all the bacteria spill out from the inner gut through all the dead tissue into the rest of the body. Long story short, ischemia or infarction of bowels and other gi organs from a hernia or any other cause is an extremely dangerous situation requiring emergency surgery and can be fatal in humans, and even with that it may be impossible to save them. I’m guessing it’s similar for dogs.
Again take everything I said with a grain of salt, your surgeon has the best information on what actually happened. I just wouldn’t get too hung up on “free radicals.” Ischemic or infarcted orgams is an extremely dangerous situation for tons of reasons.
Totally this I read an absolute ton (and more even if you count audio books, which I do) and the vast majority is from the library. Even easier now with ebooks and apps. I’ve still got a pretty full bookshelf though of things like Illustrated editons, some real nice printings of some of my favorites, older books, and comics/graphic novels.