Celebrate pet birthdays?

When we found my dog Oree and took him to the vet, he said he could tell from his tooth eruption that he was almost exactly six months old. Going back from that day put his birthday in mid-February, so we picked Valentine's Day. In the morning we make a little cake out of peanut butter, applesauce and whole wheat flour and take all the dogs in our family (there's six of them) to the park. We give them a small piece of cake and let them play in the park and the pond, and Oree gets replacements for the balls he's always tearing up.