I am so very sorry you lost Sugar. It’s not possible to say what took him. These things can happen with rabbits, perhaps because they are so good at hiding any signs of illness. We have to go by their appetite, the look of their poop, they’re general behavior. As prey animals they can’t afford to let on if they’re not feeling well because that exposes them to predators.
And we can’t know that he didn’t feel well. In Europe and Australia there are a couple of rabbit viruses that kill very fast and cause internal bleeding, so if you’re in Europe or Aussie and your rabbit wasn’t fully vaccinated, that could be a possibility. But there are many other things that can go wrong quickly. Cardiac arrest from a congenital heart problem, kidney failure, a ruptured liver are a few things that can lead to death very fast.
There is no good way to prevent this sort of thing. We can only control so much. It doesn’t sound like you did anything wrong. You fed him, he ate, it was like any other night. You had no chance of knowing that sth wasn’t right.
Binky free, little ****Sugar****