Puppy died?

I had a game notification yesterday. Puppies are fine. Today, the notification says that a puppy died from a bite. On my den page there was no "sick wolf" icon for any of the puppies and I have been trying desperately hard to keep everyone fed and happy, failing since the site is still new. However... how did my puppy die when I never had any warning it had been "low" on health?

Puppies have a mechanism called survival chance which decrease by 15% everyday that the puppy/or the mother when less than 2.5months old is not fed/played to 100%. By the looks of the mood and hunger of your current wolves, it's likely that survival chance of the puppy dropped low enough that at roll over the death roll hit.

all pups have a survival chance bar. if it’s not at 100%, they have a chance to die, regardless of their health

Puppies have a survival bar. At rollover, there's a chance for them to be injured or killed if that bar is anything less than 100%. The two puppies in your den now have 62% of their survival bar filled - meaning they have a 38% chance of dying or being hurt at the next rollover. 

By the way, if you're having a tough time getting enough food and toys for everyone, check out the 'items' chat under stockpile. There's several threads in there dedicated to getting people food and/or toys for free or cheap.