I am very particular and careful about the treats I allow my dogs to have. As the other thread, Bad Treats, clearly shows, many of us are aware of the importance of buying natural treats with ingredients that are biologically appropriate to our dogs.
I LOVE beef lung and it is one of the best things you can give a dog. The brand and quality of it however is critical. I am not aware of this kind and the only brand I use is Merrick simply because I know their processing and quality. Merrick makes several good treats for dogs.
I also like Gambon's Pro-Treat Beef liver - 100% liver and no other ingredients.
Otherwise, like many others - I use homemade treats.