The angle gauge (Fig. 1) is a useful reference tool.  To be helpful, however, it needs to be used appropriately. 

Several factors can affect the reading of an angle gauge. First, the gauge itself could be incorrect. If the arm of an angle gauge gets bent, it will no longer yield an accurate measure. If you take several gauges that have been used many times, it is very possible that they will not all give the same reading on the same hoof.

I have often found myself looking at a shoeing card that shows a hoof angle I cannot possibly achieve with the hoof growth shown since the last shoeing. There was no way I measured the hoof the same as the last farrier who worked on that horse.

(Photos by the author) Fig. 1: The angle gauge can be used to accurately measure shoes.

A simple tool to calibrate the gauge is a block of wood, wide enough to span the gauge, cut to a 45-degree angle at one end and 60 degrees at the other end. Once set, the gauge will remain the same unless kicked, stepped on by a horse, or knocked around in the shoeing box too much.

Another factor affecting your readings is the hoof itself.  No, I do not mean that actual hoof angle can change; that is a given. I refer to the profile of the dorsal (front) part of the hoof wall.  If the profile of the dorsal wall is rounded, usually bulging out midway up from the ground, this will give a false reading on the angle gauge.  Usually, that false reading is about 2 degrees higher than it actually is. Bruce Nickells used to call these “frog bellies.”  I don’t know if that is what a frog belly looks like, but I do know Bruce didn’t want them on his horse’s feet. 

Very often when you remove that “frog belly,” you will often find a linear bruise (Fig. 2) across the hoof exactly at the peak of that distortion identifying a newly formed stress point that it created. 

Fig. 2: A linear bruise, like the one on this horse's hoof, can result from incorrect shoe sizing.

Fig. 3 shows two hind feet. The far hoof has been dressed back to normal and the near hoof has not. Both read 55 degrees on the gauge.  Having dressed the first hoof, it then read 53 degrees and altered the way I chose to trim the hoof and regain those 2 degrees.  If I didn’t dress the near hoof before checking the angle, I would trim the hoof to maintain the current angle, missing by 2 degrees.

Conversely, a “dishy” hoof will distort forward in the lower half to lower two-thirds of the dorsal wall.  This can also be evidence of a club foot, which will have a much higher heel than the normal hoof. The dishy part of a club foot (or a normal foot) can make the angle gauge read much lower than it truly is. After removing the dish from a club foot, one may find a hoof angle of 55-60 degrees. That is very high for a front hoof (club feet are nearly always fronts and usually only one foot). 

I do not recommend trimming the heels of this type of hoof down to try matching the other foot.  This will lead to greater problems.  Club feet are managed, not corrected.  Trying to make them the same because the angle gauge says so is the wrong approach. But whether the hoof is clubby or simply distorted, that dish will affect the reading of your gauge.

Fig. 3: An undressed hoof, like the near hoof in this photo, can lead to an incorrect angle gauge reading.

As I stated to begin this article, the angle gauge is a good reference tool. Once the hoof is trimmed and dressed, the angle gauge gives a good baseline from which to work. If the horse travels well like that, it can be duplicated the next shoeing, provided the hoof is dressed if needed and the gauge is accurate. 

With a horse that really needs to be spot on, and is traveling track-to-track using different farriers, it may be a good idea for a trainer to use his own gauge each time. Sometimes getting back to where the horse was traveling best is a bother once the reference is lost. I find it best not to trim the horse to the gauge, but to trim to the conformation, then gauge the result.

I don’t believe in changing horses that are going well; however, looking higher up the leg than just the number of the bottom of an angle gauge can pay big dividends in terms of avoiding trouble in the future.

Getting the trim correct in the first place is the most important part. The ability to repeat it is not just a numbers game. It is a key to long-term success. And remember, win pictures look good from any angle.

Veteran Standardbred farrier Steve Stanley of Lexington, Ky., authors a monthly column for Hoof Beats, the official harness racing publication of the U.S. Trotting Association. The American Farriers Journal Editorial Advisory Board member offers plenty of practical advice that will be of special interest regardless of the type of horses that you work with. Click here to read more from Steve Stanley's Hoof Beats series.