Does anyone have any familiarity with this one?
It came to my attention yesterday when i read a post on a dog health mail list, about there being a synthetic form of vitamin K, menadione, that's often added to dog food as an inexpensive form of vit K, which is harmful to the liver. it was said that this substance is used in some of the better dog foods as well as the others. The poster said that this brand, Nature's Variety Prairie, has just recently stopped using menadione/K3 because of the concerns.
Here's a link i just found when trying to find out more information about what the problem is with vitamin K. It's not a problem with vitamine K, but just this form of it, which has been prohibitted for use in human food in some european countries, and the FDA/US has some kind of restriction on it.