05/07/2022
Unfortunately negative palmar angles is a common finding in the horse population, leading to an extensive number of other ailments and injuries. Radiographic interpretation can help assist both farrier/trimmer and veterinarian to look at the internal structures of the foot and help correct the angles. It starts with a proper trim and paying attention to the healthy and non-healthy structures of the foot.
I went for a little walk around the local show park yesterday during the season opener hunter/jumper show. I try not to look down at horse feet unless someone asks for my opinion, but despite my best efforts, I couldn’t stop noticing that most of the horses there, from the low level hunters to the 1.20m jumper class I watched for a while are very obviously NPA and/or showed obvious signs of caudal failure. NPA means “negative palmar angle” on front feet or “negative plantar angle” on hinds. It means that the back of the coffin bone is lower than the front. It is supposed to be the other way around! A normal palmar/plantar angle is 2°-10° yet soooo many horses work on feet with palmar/plantar angles of less than zero. It is so common that by most people it is seen as normal. Caudal failure means structural collapse of the caudal (back) part of the foot.
Horses may not be obviously lame with this condition, however there are often subtle signs. Reluctance to go forward, forging (stepping on or hitting the backs of the front shoes with the hind feet), overreaching, not tracking up, refusing jumps, bucking after jumps (because landing hurts), lack of hindquarter engagement, decreased gait quality all around, behavioural issues under saddle, etc. These symptoms can be easily mistaken for other things or riders and trainers can tend to use punishment to try to change some behaviours that have their root in hoof pain. It is also very hard on the legs and most specifically the DDFT (deep digital flexor tendon) and navicular area of the foot because of the biomechanics of a foot with an improper angle cause increased friction where the DDFT runs under the navicular bone to attach to the back of the coffin bone. This is why low heeled horses are at increased risk of developing navicular syndrome.
We need to retrain our eyes to know what is normal. We also need to realize that asking horses to work hard when their feet are a mess is not fair and causes sometimes irreparable damage, both to their feet and to their opinions about working.
How do we fix it? First we need to acknowledge that NPA is a systemic issue in farriery and we need to change the way we trim and shoe. Owners need to recognize NPA and find a farrier who recognizes NPA and knows how to fix it. Farriers need to stop trimming off the back of the foot and add frog support to our shoeing packages. Frog support needs to be normalized. More than one client has remarked to me that if we put frog pads on the horse, potential buyers will think there is something wrong with the horse. This is because what is normalized currently in farriery are open heeled regular metal shoes, which are a huge part of what causes NPA. When we lift up the foot off the ground and provide no structural support to the frog, the center of the foot collapses. This is a very simple concept, yet we are still doing things the same way we have always done and expecting a different result. This is the definition of insanity and it is killing our horses slowly. If I help to change only one thing in my time as a farrier, I hope for it to be this.
For reference, normal/ideal angles are generally as follows:
Hairline: about 20°
Dorsal wall (toe): about 50-55°, steeper on some breeds
Heel: equal to toe angle or perhaps 5° less than dorsal wall
This horse’s toe is close to 50° however the heel is 23° lower than the toe and I could not even measure the heel at the back because the bulb is sitting on the shoe! I had to measure it where I could see the angle of the tubules on the wall. The hairline is far too low. This foot is not helping this horse at all and this horse is one of many. I might get some angry messages for this, but we need to acknowledge that most of our performance horses are NPA and/or have some degree of caudal failure and then then we need to do something about it.
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Addendum: This post has pi**ed off some people. Fair enough. It’s also been shared all over the world, which has been great and also quite the experience. Wayne over at Progressive Equine has been writing about caudal failure and NPA for a few years now, as have others. This topic is not new. For whatever reason, this post in particular has caught peoples’ attention.
What I ask of those who are angry about it, or indignant that I dared to challenge the status quo is this: if you think I’m wrong, ok. Go prove it. If I’m wrong, why are you angry? If I am wrong, then this post is irrelevant to you and irrelevant to your work and there is nothing to be angry about. I did not (and will not) name any particular farrier. Who did the job is not even relevant, because this problem is not about one person. I am not trash talking anyone. I am saying that there is a systemic issue in how farriers are taught to trim and shoe and that it is on us, as a group, to correct it by continuing to learn and grow. That is my perspective. If you think I’m wrong then disregard it. And yes, some horses manage in regular shoes and to the owners and farriers of those horses I am glad for you. For everyone else, maybe what I wrote here will help you. That is all I am trying to do.