I buy the Pup-Peroni training treats which are already a small size since they're training treats, but I break them up into even smaller sizes (I usually break one treat into about 5+ smaller treats). That way I can train with Ruby longer since I'll have more amounts of treats. I don't like her to have more than a few treats so it works out nicely. Especially since she isn't as attentive working for plain dog food as she will for her treats.

I'm sure whatever you choose as long as you just limit the amount you give your dog it'll be fine. Keep the quantity small and they won't have a huge fat intake. I use dog treats because that's what gets Ruby's attention and keeps her focused more than anything. Good luck