Normal and Not So Normal Horse Feet

Hoof conformation and internal anatomy are vital to the performance of the horse; whether if they are an elite athlete or back yard pleasure critter.  It is easy to visually look at the foot or hoof and see that things appear to be normal, but sometimes we need to pull back the covers and get a better look through x-rays.  Unfortunately, most x-rays are only taken when problems develop and it is then that we discover that things have gone off course over time.  It is common to trim the feet to meet our expectations visually and sometimes to alter performance or movement of the foot, but we need to take a look at the inside and see how things are balanced before major work occurs. 

As a veterinarian, I don't get the chance often to take x-rays of 'normal' feet.  Every time that I do take films of a horse, especially the feet, I take time to review them with the owner, pointing out structures so that they can understand what is going on inside and how this impacts things on the outside.  Often feet are trimmed too small, too short, have under run heels or very thin soles; which then contributes to the performance and well being of that animal. 

Anatomy is important and I think every horse owner should understand what is going on internally.  Given this, let's look at a couple of 'normal' or actually as close to normal as I can find in my data bank and review some structures.  In order to know abnormal, we must first know normal.  This holds true for everything.  The second thing to remember is that no horse is perfect in conformation or anatomy.  If they are not perfect, we need to resist the temptation to make them perfect by trimming or shoeing.  It is when we strive for perfection that we create problems, especially lameness.

Normal Foot Anatomy

The x-ray to the right is of  the LF foot of a QH gelding.  Again, this is the closest to 'normal' as I can find, but it will serve the purpose of helping us to determine what is normal and where things should be.  This x-ray is from the fetlock down, including the hoof capsule.  For starters, let's identify the bones present.  Here we have P1 (fetlock bone), P2 (Pastern bone), P3 (Coffin bone) and N (navicular bone).  Now we have a series of colored lines that have been assigned to the film.  The YELLOW line indicates the angle of the bony column of P1, 2, 3.  Ideally, they should be at the same angle as seen in this film, all in alignment with one another. The YELLOW line should also be relatively close to external or visual angle of the fetlock region when grossly looking at the horse.  Next we have the WHITE line, which indicates the angle of the front hoof wall.  This angle should be relatively close the angle of the bony column, so White should equal Yellow for all intensive purposes.  Now, we have the BLUE line, which indicates the solar angle of P3.  This line or angle should not be flat but should have a slight upward slope, as we move towards the heel.  The final line is the RED line, which indicates grossly, the sole thickness, which is the distance between the bottom of P3 and the outside world or bottom of the sole.  In my book, the absolute minimum sole thickness is 10 mm.  Anything less is too thin.  I'd rather have too much than too little.

Not So Normal Hoof Anatomy

So, as I mentioned, sometimes things look good on the outside but when x-rays are taken, we get a whole new picture of what is really happening.  Take for instance this photo

of the LF of a QH mare.  Taking into consideration points we mentioned above, let's look at the angle of the fetlock in relation to the angle of the front hoof wall.  In this horse, the fetlock angle is not exactly the same as the front hoof wall angle, which ideally they should be close.  The heel region of the foot appears to be decent, could be a little better in terms of heel height, slightly under run but not horrible on the outside.  The hoof itself is in rough condition, dry and brittle with cracks evident.  The hoof  is non-pigmented, which generally to me is a weaker tissue than pigmented, but if we look closely, we can see a red area on the outside quarter, which is actually a bruise or gathering of blood. This horse actually presented for a chronic lameness, which was isolated to the foot by examination.

Now, lets take a look at the inside with an x-ray.  Again, you have to remember normal to know abnormal.  Here for starters, we see that the bone column is off in terms of angle, it is too steep and doesn't match the angle of the front hoof wall.  When these angles are off, it signifies generally that we have rotation of P3 or laminitis.  We can also see that P3 is essentially pointing directly down towards the ground surface with the tip of the bone almost penetrating the sole.  The soles are extremely thin as well, which is complicating matters and making it easier for P3 to push through the sole.  This mare was essentially walking on the tip of P3 and when looking at the solar surface visually, the sole was pushed outwards due to bone penetration.  We can also appreciate the lack of health of the hoof as well in this x-ray due to the cracking and breakdown noted at the tip of the hoof.

Lets take a look at another for comparison sake.  This is an mid-aged Hanoverian gelding.  He was actually sound with intermittent flare ups of lameness.  Visually looking at the foot, we should for starters look at the angle of the fetlock and compare to the angle of the front of the hoof wall.  If you look closely, you will see that they are different.  The hoof angle is more upright and the pastern more sloped. The hoof looks good with decent heel angle and height in my opinion.  The disparity of these angles can be due to a lot of issues, but in this horse the problem was that he was born club footed.  The severity is not too bad but likely contributed to his ongoing lameness issues.

Here is another photo of a more severe case of club footed in a youngster.

As you can see in this photo, the front hoof angle is very steep and actually is about the same as the fetlock angle.

There are so many changes that can be detected when x-rays are taken.  So much information can be gathered.  Let's take a look at couple x-rays of more abnormal foot pathologies.

In the case the right, we have a very upright bony column or pastern angle when compared to the front of the hoof wall.  On x-ray, we have evident rotation in the amount of 11 degrees.  The solar angle is too steep as well but the sole thickness is actually really good and is helpful in this case in terms of aiding in he realignment of the anatomy during trimming.

The case to the left is a patient presented for ongoing lameness.  This case demonstrates many issues at hand.  First, you can see that the hoof wall is abnormal, kind of lumpy bumpy with abnormal growth.  The sole thickness is decent, but we have a rotation of the coffin bone (P3) in relation to the front of the hoof wall as well as the angle of the bony column, which is designated by the RED line.  The rotation was ongoing or chronic and there are changes here to indicate this.  First, the tip of P3 is worn, more or less rough looking due to ongoing trauma to that region.  Second, we have low and high ringbone development present likely due to ongoing stress to those joints as well as genetic conformation issues.


The foot of the horse is a very interesting topic to me and I love to explore with x-rays to really get a good idea of what is going on.  Sometimes, we will be presented a horse for a pre-purchase examination with evidently good looking feet and soundness, but discover many problems when we look inside.  I don't feel that there is a specific angle for each and every horse, many do, but I do not.  I do believe that it is important to try to keep angles as close to one another as possible, but we have to accept deviations from the normal, especially in cases of a horse being club footed.  I feel that in many of these cases, we try to trim that poorly angled foot to match the more normal one and in the process, we create more problems due to shifting of anatomy that was not meant to be shifted or stressed.  I also feel that it is important to monitor sole thickness as one of the biggest problems we encounter is thin soles due to genetics, poor nutrition or just over zealous use of the rasp.  We have to understand that once a problem is created, it can take months if not years to correct that due to slow hoof regrowth.  It is always best to air on the side of caution and snap an x-ray if there is any question before removing hoof or sole tissue.

I hope you find all of this useful!  There is much to discover and no two horses are exactly the same. 

All my best,

Tom Schell, D.V.M.
Nouvelle Research, Inc.
www.curost.com