My dog has a very sensitive stomach but is also a challenge out and about so I get through a lot of treats! I've tried a lot of different types including the major brands and none of them suited him. I was searching for single protein training treats and came across Proper Natural, I've tried their cube training treats in all the flavours (my dog has tried them not me!) and haven't had any ill effects. My dog loves them and it's brilliant knowing exactly what they're made of and that I'm not upsetting his insides. I've just ordered another batch and to top it all off they're great value for money. Highly recommend these!