When I first bought Peaches hers I put in a bowl with Chicken Stock overnight. I have never seen her go more nuts over a toy! Other then that 1/2 a teaspoon of Peanut Butter, Liver Paste. You can also get the Kong Stuffing you don't need much so the price even's out pretty quickly. Other then that any treats that they like as long as you shove it up the top where they can't reach it, or on the side. Hope that helps :-)
Kong makes cannisters of basically spray liver. It's horrible to consider as a human, but super tasty for dogs! Not sure where to buy it, probably most pet stores carry it!
https://www.amazon.ca/Kong-72186-StuffN-Treat-8-Ounce/dp/B00008DFK5 this horrible, delicious stuff. Otherwise maybe try cheez whiz or try and find low sodium pate? Short dog problems!