
When I was at clicker classes I was always told to make the food as tiny as only possible. So for instance a hot dog, one of these small thin ones from a jar, you would cut into thin slices like coins, and then each slice would be cut into four pieces. That's for a large dog.
Few treat manufacturers seems to understand that not all dogs are giant, and so I have only ever found one shop bought treat small enough to use for Papillons -most are so big they could lay down and chew them for half an hour before it was gone. I want a treat to be gone in a second so that you can give it without having to stop what you are doing, such as if you are practising heelwork. Anything that requires chewing is too big. Now most shop bought treats are really too boring to use anyway, but sometimes you want something quick and dry as opposed to the usual hotdogs, sausages, chicken, ham etc. I would LOVE to see really tiny versions of the Fish 4 Dogs, Mariners Choice etc fish treats. They are the favourites of my Penny who weighs in at 31 kilos (lean but very tall) -she will not eat sausages. It takes her 3 or 4 chews to eat one fish treat, they are that big.