It’s easy to see and understand hoof width - measuring from the widest point to widest point in a straight line across the hoof.
However, hoof length is tricky because we must be able to determine the rearmost point of weight bearing at the heels.
In the photos above I sprayed a light coat of black lacquer paint onto the bottom after which I drew the smooth side of my rasp across the heels to remove the paint and some hoof wall. Doing this served to provide a clean flat surface at the heels with the paint improving contrast.
As you can clearly see, the rearmost point of weight bearing is at the colored line drawn across the back of the heels. If you have trouble projecting an imaginary line onto your tape measure, you can apply a piece of masking tape or duct tape onto the hoof with the back edge of the tape aligned with the heel.
Another way to look at this is to imagine for a moment you applied wet paint to the bottom of your horses hoof and then walked him across a smooth hard surface. When looking at the hoof prints left behind by the wet paint, the rearmost point of weight bearing would correspond with the rearmost point of the print but not counting any print left by the frog. I’m not recommending you measure the hooves with wet paint, but this example may help you visualize what I’m talking about.
In addition we need to discuss heel shape as most heels won’t be nice and flat with crisp edges as depicted in the photos above. Somewhat rounded off heels are more typical, especially for those horses landing heel first which is natural. Some trimmers will also intentionally round the heels to help promote a heel first landing and to help mimic the rounded heels found in the wild hoof. I’m an advocate of intentionally rounding the heels which I call Reverse Breakover.
Fortunately we do not need to drive ourselves crazy figuring out the exact hoof length. Simply make your best guess as to where the rearmost point of weight bearing would be if the heel were flat and not rounded and this will usually be close enough.
