I found this recipe:

Rudy's Pet Frosting

1/2 stick of butter
1/4 cup dry cat or dog food
1/2 cup sugar
1 to 2 Tbsp milk or water
1 Tbsp flour if needed for thickening

Put everything in a food processor and mix well until desired thickness. Spread on pet's favorite cake or cookies. This is for occassion treating only. Store in airtight container in refrigerator

There are other recipes for Dog biscuits and stuff on the website I found this one on (Newf Goodies Dog Treats)
I havent tried any of them, but I thought I would refer you there, I was also looking for a frosting recipe.... If you find one for the yogurt one please post it here so I can try it out!
Thank!