You can always try......

When I make frosting that hardens for Gingerbread houses I use an egg white base (liquid) or Meringue powder (dry powdered egg whites) then add the sugar,

but for dogs instead you could try adding the Meringue powder to the yogurt paste to see if it will work. I am certainly going to try.

also Cream of Tartar helps absorb moisture.

Yogurt paste- (easy to make, take a container of natual balkin style yogurt and pour into a strainer lined with cheese cloth, let sit over night, stirring occassionally, the whey will drain out)

Good luck!

~Donna