To measure the fold of flank of your pet
Step 1: Fold of Flank
The Fold of the Flank (FOF) is a thin piece of skin that connects the dog’s upper rear leg to his body.
Look at the webbing between your thumb and index finger. This skin is very similar to the fold of flank (FOF).
Step 2: Armpit to Rump
To measure the Armpit to Rump, start from the back of the front leg and measure across to the back of the rear leg.