Cut the meat into uniformly thin slices about 1/4 thick or less. The pieces can be large or small as long as the thickness remains consistent. The overall size should be slightly larger than the size of the treat you'd like to end up with, since they'll shrink as they dry out. Smaller pieces are great for training and long, thing strips will keep little dogs busy for a minute. If you're using a tougher cut of meat, try to slice against the grain so the dried treat isn't stringy. Slicing the meat thin is a little easier if it's just barely frozen, especially for soft cuts like liver.
Arrange the slices, flattened, onto the racks of either your dehydrator or wire racks. Avoid overlapping the pieces and leave about a half inch of space around them to let the air circulate.
Set the trays in your dehydrator, or the wire racks with cookie sheets underneath in a preheated oven set at its lowest temperature (200 degrees is great). From here it’s a bit of check-and-see. Drying times will vary depending on how much meat, the cut, the kind of dehydrator, and the accuracy of your oven. Rotate the racks every two hours or so and start checking for “doneness” after about three hours.
If your dog is older or has some issues with her teeth, you may want to take the treats out of the dehydrator when there’s still a little give to them; maybe 4 hours in. Softer jerky will also smell “meatier” and can be cut into tiny pieces, making them ideal training rewards for puppies. Or, let the meat strips continue to dry go until they feel hard to the touch, about 8-9 hours.
Let the jerky cool completely, and then store the treats in an airtight container. If you’ve opted for the softer variety or have used a fattier cut of meat like tongue, the treats aren’t fully shelf stable and are best stored in the freezer; just pull out a handful as needed to store in a mason jar on the counter for no more than a few days. If they’re the fully dried kind of doggie jerky, they’ll last in an air-tight container on a shelf for several weeks.