Anterior / Posterior balance
This one is a bit trickier than M/L balance as there are more things that can distort than in M/L balance. With AP balance you can get coronet band shift, negative palmar angles and damaged cartilages as well as under run heels, excess sole, restricted blood flow.
A/P balance can best be picked up from coronet angle and solar concavity as well as the stance of the horse. If you have not read the other articles where I tell all trimmers and shoers to get out there and learn to be a massage specialist before they touch the horses hooves or form an alliance with a local massage specialist and pick their brains. Get out there and learn about the body it will tell you much about the feet.
If a horse has tight hamstrings and a hunched lumbar you can be certain the horse has too much toe on it hind feet. It will stand under with its hinds and be unable to trot smoothly.
The wonders of barefoot trimming are becoming more and more amazing to behold. I trimmed an old mare that was well and truely retired, part of the reason for her retirement was just that she had never been a comfortable horse to ride. It was literally bone jarring to sit in the saddle. After her third trim we watched her move off to rejoin her paddock mates. She went from standing still at the gate to a slow walk then a medium walk to a fast walk, then a slow trot to an extended trot to a canter with no sharp movement. It was brilliant to watch just like fluid moving, the horses back never changed angle or moved out of a floating position. Unfortunately it took until the horse was retired to allow her to move like a horse but it was nice to see that all those years of poor hoof care can be undone in 8 weeks.
A/P balance without X-rays is more of a gut feel thing instead of being able to rely on your good friends the collateral grooves. Part of the reason for this is that the key marker you are looking for is the tip of the pedal bone and trimming too close to that is disastarous. You can sort of get a feel if a hoof has too much solar concavity or the front wall of the hoof is showing a bulge where the pedal bone is tilted backward. Sometimes it is just the way the horse stands or it might be muscle damage.
A good guide to excess hind toe is a cowhocked stance. The pain of the tendon running under and up to its anchor point under the pedal bone can be so bad the horse points its toes outward to shorten the distance to the anchor point. In some cases the horses have been seen with tight hamstrings and bruising at the insertion of the DDFT where it is trying to tear away.
One foot in mouth moment this year was a fantastic example. I was out trimming horses that my favourite horse shoer was working on. We brought one horse out of the box and headed for the farrier room. As the horse was walking I could see the tension in the hamstrings. So I asked him to stand the horse up as I suspected it would stand cowhocked and it did. I was showing the man the ropes of barefoot trimming and what we looked for. So I explained how badly out of alignment these feet were in an A/P balance fashion and where the pedal bone would appear on X-rays based on what I can see in the hoof wall changes.
Then I realised belatedly that the man who had created these problems was avidly listening to my explanations. Oops, oh well now I have to prove my point about these problems. I checked the hoof over for signs of what was where and how, I then proceeded to do the thing most barefoot trimmers would freak out at and that was to carve out excess sole at the toe. Yes you heard right I dug the sole out at the toe. Why in gods name I hear you ask. Well my mentor Martha Olivo probably the worlds best trimmer stated in her training "trim what you must, leave what you can". This means if it is not supposed to be there remove it, there is no sanctity of tissue if it is wrong then it is plain wrong. No ifs or buts if it don't belong it don't belong.
BUT you must be certain what you are doing is right and harmless.
Martha's number one training tip is listen to your gut when trimming, all the little signs you do not consciously see build up in your senses until you get this feeling deep down that you have reached an invisible limit that should never be violated.
If you step over that invisible line you will do damage sometimes very obviously.
Anyway back to the toe trimming, I dug 1/2 an inch of what some would consider live sole out of the toe of the hoof. All this with the person who had previously shod the horse watching on. I had that feeling of go no further this trim and commented that I was at the safe limit of trimming the hoof back to the right shape. So with a good rounding of the toe I have removed nearly 3/4 of an inch excess toe. The horse almost gave a sigh of relief at the removal of pressure from the wrong shape of the foot. DO NOT even try this until you understand bio-mechanics and hoof structure but be aware that it is sometimes the only way to undo the long slow damage to a hoof, by bad balance and changes to vasculation and circulation. Remember every thing in the hoof is driven by circulation, from growth to impact absorbtion to repair
The horse was completely sound and able to work and the pain in the legs and back faded away very quickly as the muscles adjusted to a normal range of movement.
Hoof trimming is not about letting it try and heal itself, you must learn what is wrong with the hoof and how that is impacting on the body. Trim the feet to fit the horse not to fit the feet.
I just want to bring to everyones attention to a thing about the back of the feet. This area being soft tissue can flex and distort in many ways but being cartilaginous it can be damaged and its connections can be damaged. This is an interesting thing to deal with as the horse will be unable to stand for a farrier and hold one hind leg behind the other. The way to test for this problem is to lift the hind leg and move it towards the horses head and move it forward and backwards a little bit and the horse should relax now slowly bring the hoof low and back through past the the other hoof. As the canon passes the other one go real slow, a mm at a time slow. If the horse has a heel problem the action of bringing one foot behind the other adds the weight of that leg to the heel of the other leg, the horse will immediately tense or hop away on the other foot until you either make it stand still in pain or put its foot down. As you move the leg further out behind the other leg the reaction will increase in intensity. Some of these horses do this for years and get hit by the farrier every time for showing a pain reaction. One horse I trim was like that for over 20 years, I realised on the first trim that the horse had a pain reaction I just had to figure out what, the first clue was the 45 degree hairline. The horse was sore in the hips the hamstrings, the lumbar and the feet it stood badly cow hocked and if it ever laid down limped around for about 5 mins after it stood up. It was suspected of having arthritis, but I could not see any problems in the hoof ligaments.
This was back before I got into equine massage but it was certainly a driving factor of realising that hoofcare people must be massage people too, to put the whole horse picture together. Being an old horse and one of my first real tricky cases I took it slow and steady, knowing how the 28 year old had good days and bad days, I now get right in there and cut away the excess so called live sole. We learn these things as we go, caution is good but it can cause unnecessary problems that you can easily avoid when you know better.
Getting back to my favorite shoer, he brought in an interesting case to the farriers room, in removing the shoes off this horse it had to be pinned up against the wall or the pole to get it to stand still to take the shoes off. I immediately recognised the problem and once he had the shoes off I told him this horse had sore heels and damaged cartilage. He quickly commented that it was just that the horse had arthritic hocks, sore hips, a bad back and lumbar problems, so he was always just like that and had to lean on a wall for support. I agreed that everything he listed could be correct but it was still the feet causing it. So I showed him by picking up the hoof and moving it all around the place in front other the other canon bone, the horse relaxed and let me do it no pain in the leg or back (Proof 1). Then I told him to watch the reaction as I shifted that leg past the other one and sure enough the horse jumped away (Proof 2). I did that to both hinds then raced out to the car and grabbed a big fluffy pad I use for trimming bad founder cases. I put that under one foot while I picked up the other. The horse flinched once as I moved one leg out past the other then he let me move it all around and do anything I wanted. The shoer said "quick do the opposite leg", so we put that foot on the pad and picked up the other one and moved it all around like a normal horse with no dancing steps (proof 3). The horse was cured no more hock pain no more back pain the only problem is he had to wear pillows on his hind feet the rest of his life :-).
This tidbit of information kept the shoer up thinking (yes horseshoers can think too, most of these end up barefoot trimmers in the end). He spent days thinking about all the brood mares that were blamed for having foals in the wrong position and old crotchety horses that could no longer bend properly for the farrier. He was going to see how he could repair it with shoes on while I had a go with barefoot. The key is AP balance and I have shown him a few ways to identify A/P balance and double check his work. The 28 year old mare I work on came good in 12 months, I could have possibly shortened this time frame by doing the better cutting of excess sole at the toe but I did not know all that back then. The end result is that it is not a quick thing to heal but as a horseshoer at least he and his compatriots now know that it is not a naughty horse thing the horse is really in pain and a pad under the other foot means he can work without hurting the horse.
The thing I kept driving home to him is that barefooting is about hoof balance and that the Hoof Pastern Axis was not the way to find A/P balance. Once the hoof got wrong it made the pastern follow it, this meant any farrier that relies on HPA was always going to have horses out of balance.