LPT: If you rescue a starving animal, reintroduce it to food slowly. Animals are also subject to refeeding syndrome, just as WWII POWs were.

Refeeding syndrome in animals works the same as it does in humans. In short, the starving body has made major adjustments in how it processes energy, and if it suddenly gets a large amount of nutrients, it throws the electrolyte balance off to the point that it could be deadly.