Growing up taking care of 2 large pelting herds of chinchillas (my Father's and Grandfather's) checking animals for priming was essential to getting a good price for each pelt. It is really simple to figure out where an animal is with priming. Start by blowing into the fur at the neck and shoulders and continue back towards the tail. Priming always starts at the head and works back towards the tail. When you blow into the fur observe the color of the skin, if it's blue it's priming and if it's white it's already primed. Wherever the line of blue is across it's back is the prime line moving back towards the tail. When the skin appears white from neck to tail the chin is in optimum fur prime. Sometimes, you'll notice blue in the neck and over the rump at the same time. This means the animal has started new prime before fully finishing previous prime. Just a little trick all fur ranchers know.