The game needs a hard reset button that completely wipes everything, I've got a few minor issues related to old saves being used and reused, plus I'd like to try re-earning the achievements from scratch.
I'm sure I could wipe the cookies or cache from this page, but that feels like more of a workaround than a legit fix.
Also I don't know if it was a bug or not, but I got the cow up to a self-sustaining point where she was fed and milked just fine, so I left the computer to do some other stuff for a bit and when I came back she was dead. No idea what caused it, but she was just out of HP when I got back.
If I ever get that to happen again, I'll pay more attention to what could've caused it or if anything could make it repeatable.