EDIT: All samples are gone now!
In order to get this, simply click the blue bar at the top of their page that says “give your pet a taste of Purina.” (if you have any ad-blocking software, you'll have to disable it in order to see the banner.)
So if you have a cat and a dog, how do you decide which freebie to get? I tried explaining to my pets that they needed to fight in a Battle Royale to see which would prevail and be worthy of the freebie. Unfortunately, my cat just looked at me and then my dog started licking herself. I'm not sure those English lessons I've been paying for are working.