I had not thought of dog food, but my main focus on treats for my chickens is along the lines (GENERALLY - I do deviate from time to time) is healthy left overs.
Yesterday I took a watermelon rind to the coop. It was the end of the melon with a bit of "meat" on it. They looked at me like "WOMAN! Have you lost your mind???" (They are just over one month old. I decided to leave it over night.
This morning, ALL that was left was a thin layer of watermelon skin.
I took them the other end this afternoon, and had to get out of their way FAST! Normally it would have been cut up and thrown in the compost pile; now it will go THROUGH the chicken and THEN in the compost pile!!
With that said, I will admit to giving them hard boiled eggs from time to time - a real party starter. (This particular treat is a bit macabre when you think about it, but it is healthy and the love it, so what the heck??) They also love shredded cheese. However, I am going to work more and more toward sharing with them the left overs instead of feeding something else I am already paying for!
Chickens are great creatures... I had NO idea until a month ago!