Reindeer Chow is the holiday themed version of sweetened Chex mix known as Muddy Buddies, or puppy chow. Reindeer Chow also has candies and pretzels. People have been making versions of puppy chow, Muddy Buddies or sweet Chex mix since at least the 1960s. Many of the early versions of sweetened Chex mix come out of the Midwest.