Mix water and broth together to make a very light broth that the dogs will love. 

Find a sturdy four cup freezer-safe bowl or dish. Add some treats to the bottom and fill it with your broth/water mixture. 

Let the mixture freeze for about 30 minutes. It doesn't need to be completely frozen solid at this point. 

Add a thin layer of peanut butter or melted tallow to the top of the ice and return to the freezer for another 30 minutes. 

Freeze the block solid for at least two hours. 

To unlock the ice block, just let it thaw on your counter for 5-10 minutes. It should pop right out of the container. You can also run it under warm water to release the block. DON'T do this if you use a glass bowl, as it could shatter from the sudden temperature change. 

Place the ice block in a large high-rimmed bowl so the dog can reach it, but it won't melt all over your floor. I also like to set a towel on the floor or place the bowl outside, so that it does not slide all over the floor.