To measure the height of your pet for our Walkin Wheels, measure from the ground to the “Fold of the Flank” as shown here. The 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 FOF.

Overweight pets:

If your dog is overweight, then the fold of flank will probably hang down from his body, making the fold of flank measurement shorter than it really is. You will need to try and move the flank up to a normal position, to get an accurate measurement. The picture of the Boxer below shows a normal fold of flank for a dog that is not overweight.

Long Haired Pets
If you have a long-haired dog, you can locate the fold of the flank by pushing the hair back and feeling for the fold of flank skin.

Tips!

• If your dog can stand, use a metal retractable tape measure or yardstick, place it in front of his rear foot/toes and measure straight up to the bottom edge of fold of the flank.
• Do NOT stretch the dog’s leg and foot out as this will add several inches to the fold of flank and give you an inaccurate measurement.

Reference: http://handicappedpetscanada.com/measuring-for-your-dog-wheelchair/