I just looked at that website. The reason they are giving away free samples of Greenies now is because they have a "NEW" forumla. The "NEW" Greenies are completely digestible. I got this from that website:
95.7% Digestible: New Greenies® dental chews are 96% digestible - that's more than your average dry dog food (80-85%). That means that your dog's body can easily absorb and use all those good vitamins and minerals that we've added to the formula!
I think that the New Greenies are completely safe. What do yall think?