I looked at a couple varieties and they have tapioca starch, which has some carb content, although the analysis content is listed and carbs can be figured from that on a wet matter basis. At first glance they do not appear terribly high carb, but I would do the calculations to double check.
A lot of people use freeze dried chicken or fish bites or make a plain chicken breast and cut in small pieces and keep some in freezer. Anything 100% meat is zero carb.
If it is for testing purposes, wet stuff is not ideal, easier to have some thing you can give by hand or put in front of them when testing.