References:

Ramsey GD, Hunter PJ, Nash MP
The effect of hoof angle variations on dorsal lamellar load in the equine hoof
Equine Vet J. 2011 Sep;43(5):536-42. doi: 10.1111/j.2042-3306.2010.00319.x
"The models in this study predict that raising the palmar angle increases the load on the dorsal laminar junction. Therefore, hoof care interventions that raise the palmar angle in order to reduce the dorsal lamellae load may not achieve this outcome."

We see a lot of horses fail to recover, or P3 penetrate the sole, when they are wearing heart bar shoes, either plastic or metal.
Some examples:

Horse&Hound Forum 2010
A 14 year old 16 hh mare had been suffering from laminitis for 10 weeks when she suddenly deteriorated and the pedal bone could be seen as a bulge in her sole.  X-rays were taken and confirmed severe rotation in both back feet with around 1 mm of sole covering the pedal bone.  Front feet were not affected.  Imprints were fitted and eased her discomfort, after which pain was only seen when she walked out of the stable.  On between 4 and 1 Bute a day, not tested for PPID (or insulin?). Mare described as always having sensitive/thin soles.  3 days after posting on a forum for help, the owner reported that the mare had been unable to put any weight on her worst foot, the bone had moved more and sunk and vet and farrier said there was no alternative but to PTS.

Lessons to learn:
X-rays should have been taken as soon as laminitis was suspected - ideally on the first day, and definitely within the first week - and the feet realigned and supported through the full solar surface.
Horses should not leave their area of confinement with wall to wall bedding until their feet are fully realigned, well supported through the full solar surface, and they are off of all pain relief.
Lifting a horse off of its soles will often reduce pain - but is also likely to leave the pedal bone unsupported, allowing actual solar penetration.
Shoes will load the walls - already disconnected from the bone - and not allow lowering of the heels but protection of sole depth in the front of the foot. 
The cause of the laminitis must be identified as soon as possible and removed/treated/managed.

Although very limited, research by Panagiotopoulou et al. at the RVC that looked at the effects of a steel shoe v no shoe on one TB gelding when walking over a platform, found that "in all cases, the shod horse showed higher concentration of stresses on the P3 than the unshod condition, with the caveat that none of these differences were statistically tested."
Panagiotopoulou O, Rankin JW, Gatesy SM, Hutchinson JR
A preliminary case study of the effect of shoe-wearing on the biomechanics of a horse’s foot
PeerJ. 2016;4:e2164. doi:10.7717/peerj.2164

Cases where horses recovered from hoof sloughing

The Helpful Farrier: Dimpled Laminitis Treatment Stirs Facebook Furor and Charitable Shoeing - Fran Jurga, hoofcare.blogspot.com July 2013
Shows a photo of a laminitic foot (A month after receiving medical support...), with a line "where the mare had tried to slough her foot before she received treatment".
​

Case Report: Laminitis - Life Data Labs Inc. 
The hoof walls sloughed off of a 13 year old Quarter Horse with severe laminitis.  The horse made a full recovery and had returned to his previous level of work 18 months later. 

All of these diagrams suggest an accurate - and therefore quite scary and severe - trim, because of the lack of sole depth bringing the trim so close to the tip of P3. It's great for a model. In reality it always pays to err on the side of caution, but keep in mind that not doing enough can be (almost) as bad as doing too much.

In reality, based on the foot shown in the top x-ray (showing the corium in thick pink) you might aim to get the true toe (the red line) rasped in the first trim - as long as the laminar wedge was stable - then put a very small (but steep) breakover bevel behind the true toe, to reduce the separating forces on the toe. Then in around 1-2 weeks, assuming that the bottom of the foot had been rasped into 2 clear planes at the first trim and the horse was now able to weight the back of the foot and relieve the front of the foot and sole, you would expect there to be a reasonable increase in sole depth in the front of the foot, and you might then take the breakover bevel back to or just outside of the edge of the true white line. The angle of the bevel is important - even a bevel just behind the true toe line, if set at a steep angle*, should help to reduce separating forces on the toe (and therefore pain and the risk of further damage).

(* aim for a bevel of around 60 degrees in the initial stages of rehabilitation, reducing to around 45 degrees as the foot improves, then finally to 30-45 degrees on the recovered foot).

Further information

For members of the ECIR group: ​Backing up the Toe - Eleanor Kellon August 2017

Toe Rocker - www.all-natural-horse-care.com 

Laminitis And The Laminar Wedge: Take It Or Leave It

​Using the Rasp (using and applying the bevel)

​

The laminae are not properly connected after laminitis.  The force of the horse's weight acts downwards on the pedal bone (P3) (blue arrow).  A frog support is supposed to support the back of the foot, but the back of the foot is not affected by laminitis and should already be well supported by the horse's own frog.  Fitting a frog support potentially lifts the front of the foot off the ground, giving the tip of P3 a hole to fall down into.
On conforming bedding the front of the foot will be supported so the risks of fitting a frog support should be minimized, but the frog support is unlikely to provide any better support than the bedding alone (and may lead to thrush, excess pressure and atrophy of the frog).
The dorsal and palmar rotation should be corrected immediately.  The purple dotted line shows the breakover bevel back to the outer edge of the true white line.  The heel/bottom of the foot trim to return the palmar angle to 3 to 5 degrees is not shown, but see below *.
​

2.  When full solar surface support is used on a laminitic foot, the pedal bone is supported and the potential for (further) rotation, sinking and penetration is minimized:

​The laminae are not properly connected after laminitis.  The force of the horse's weight acts downwards on the pedal bone (P3) (blue arrow).  The foot in front of the true white line is not stable and should not bear weight - the dotted purple line shows the breakover bevel needed to bring breakover back to the outer edge of the true white line, to more stable foot.  With full solar surface support fitted, the pedal bone is fully supported, and the ground reaction force acting through the solar support (green arrows) can oppose the horse's weight (dark blue arrow) and any further displacement of the pedal bone (turquoise arrow) - the pedal bone has increased stability.  See image below for how the realigned foot would look with full solar surface support. 
​Conforming bedding may support the foot adequately and whilst a laminitic horse is on wall to wall deep conforming bedding, extra support may not be needed, but if a horse is not fully comfortable, padding the full solar surface should be tried and the horse assessed to find optimum comfort.
As above, the dorsal and palmar rotation should be corrected immediately.
​

3.  When the heels are high (i.e. there is palmar rotation), extra support may be needed beneath the frog so that the frog shares weight bearing with the rest of the solar surface, while waiting for realigning trimming to lower the heels and return the palmar angle to normal.  However, there should be frog support PLUS full solar surface support (both supports will usually be made from the same material, e.g. EVA foam), and never frog support alone for the reasons given above.

​Raul Bras, in his chapter on Solear Support Techniques (in Equine Laminitis edited by Belknap, Wiley, 2017) says that over the last 25 years it has become routine for acute laminitis cases to have the sole and bars as well as the frog supported with pliable material.  He states that it is likely that applying supportive material to the whole solar surface of the foot will provide support to the pedal bone (P3), but that using frog support has not been proven to greatly improve support of the pedal bone, and therefore it may be more effective to provide support to the entire sole and the entire solar surface of the pedal bone.  Supportive materials used should be similar in hardness/firmness to the horse's frog, and include EVA foam, closed-cell foam and impression material.  Discussing frog supports, he warns of pressure around the coronary band from fixings used, suggests that they frequently move out of place, and cautions that no research supports their use.  He concludes "it is likely that the greater surface area of the sole addressed by the sole support (especially the dorsal aspect of the sole), the more support will be provided to the DP" (distal phalanx/P3).

It is very important that sole support does not adversely affect the already compromised foot, and thought should be given to the material and design used and to ensure that pressure is released during hoof flight.  Dr Taylor (see below) suggests using a shallow air space beneath the margin of the pedal bone when the sole is very thin or perforated.  However, if used both the position of the air space and the horse's comfort must be checked regularly, as we have seen the use of an air hole allow the pedal bone to penetrate the sole in a foot that hadn't been correctly realigned.
​ 

Jonathon Merritt, Helen Davies and Andrew Parks say, in their chapter on the Digital Biomechanics Relevant to Laminitis (in Equine Laminitis edited by Belknap, Wiley, 2017) that the pedal bone may be supported from below by forces transmitted from the solar surface of the hoof, and that "increasing support from the sole may assist in reducing the force on the lamellar junction."

​In 2014 Dr Debra Taylor published a paper describing the laminitis rehabilitation protocol that returned 14 out of 14 horses, many with significant rotation and sinking, to their pre-laminitis level of comfort.  The hoof care method used the full solar surface to support the pedal bone (P3), protecting the sole during weight bearing by using foam rubber pads and/or dental impression material inside hoof boots (or casts).  

See Section 2.3:
Taylor D, Sperandeo A, Schumacher J, Passler T, Wooldridge A, Bell R, Cooner A, Guidry L, Matz-Creel H, Ramey I, Ramey P
Clinical Outcome of 14 Obese, Laminitic Horses Managed with the Same Rehabilitation Protocol
Journal of Equine Veterinary Science Volume 34, Issue 4, Pages 556–564, April 2014 (online 05 Feb 2014)
​
See also:
Solar penetration
Robert Bowker Hoof Anatomy Videos

* The realigning trim restores the palmar angle to 3 to 5 degrees (by lowering the heels gradually) and returns the wall at the toe to being parallel to the dorsal surface of P3 (by following the correct new wall growth beneath the coronary band).
See Recognizing and Treating Rotated Hoof Capsules - Pete Ramey
​Realigning Trim

NOTES
​The digital cushion is a natural shock-absorption mechanism, which, when well developed, consists of strong
ligaments that have adapted into fibrocartilage.
 
Myxoid tissue is a primitive connective tissue (similar to stem cells) that can adapt and respond to whatever is needed if it is stimulated correctly.  It is important for the formation of fibrocartilage from fibrous tissue, especially for the frog. 
 
Digital cartilage consists of fat cells, myxoid cells and elastic tissue with a fair number of blood vessels between the ligaments.  As the digital cushion develops, ligaments start to thicken and the myxoid tissue contributes to fibrocartilage.
 
In a well developed foot, these ligaments run under the DDFT connecting the lateral cartilages, like a trampoline.
 
Fibrocartilage is tissue that is halfway between cartilage and fibrous tissue; it develops or adapts in response to stimulation of the foot under compression/strain.  Under compression or strain the fibrous tissue tries to protect itself by producing fibrocartilage – this is a normal adaptive response, not a pathology. 

In 1941 the Germans had discovered the ligaments in the foot, but not the blood vessels.  People have claimed there are scant numbers of blood vessels between these ligaments but there are in fact a fair number of blood vessels. 
 
When the foot is on the ground, the ligaments become taut and the volume of the frog increases (causing negative pressure) – RB believes that this causes much of the blood in the foot to be directed into the vessels in between the ligaments, causing it to start to swell (like erectile tissue) and thereby supporting the navicular bone and the DDFT.  In a good foot the navicular bone sits on a cushion of thickened ligaments and blood vessels.

NOTES
Dissections of horses with navicular syndrome (NS) show a lack of ligaments and fibrocartilage or damage to ligaments in the digital cushion, damage to blood vessels and pathologic DDFT tissue.  They have less of a cushion for the navicular bone.
 
In comparison, a “good” foot has robust ligaments and a developed digital cushion beneath the navicular bone - “like a training shoe”.
 
When a foot with NS is loaded:
1. it can't support the navicular bone/weight because it doesn't have strong enough ligaments and vessels (due to damage), and
2. the vibrations can't escape the foot, setting up a continuous vicious cycle.
 
In a “good” foot, the lateral cartilages added together usually make up 25-37% of the total width of the foot, and the blood vessels are inside of the cartilage itself.  When the vessels are inside the cartilage, when the foot hits the ground, the vibration shock wave goes up through the heels and the vibration is transmitted through the lateral cartilage and can get into the blood vessels to be transported out of the foot.
In a foot with NS the total thickness of the lateral cartilages is less than 10% of the width of the foot, and the blood vessels are on the inside of the lateral cartilage.
 
When there’s no support for the navicular bone:
the navicular bone starts to move on P3 and starts to sink towards the ground, and
the blood vessels are damaged – the vessels not only provide support for the navicular bone but they also nourish the DDFT and other ligaments.  Pathology of navicular syndrome shows that it occurs outside of the navicular bone itself & beyond the pressure of the DDFT against the navicular bone. 
​
Navicular is an entire foot problem - it doesn't just affect the navicular bone.

NOTES
The frog should not be trimmed (between the collateral grooves and the tip of the frog apex), it should be swollen, large and on the ground/weight bearing.

When the foot is trimmed to remove the bars so that they are no longer weight bearing, peripheral loading of the walls is increased.
 
The hoof should support the thickest part of P3 through the collateral groove/bar area.

When shod, the load of the foot is distributed around the shoe. The rim of P3 is the thinnest part of the bone.  When the foot is loaded peripherally, the rim of P3 becomes susceptible to problems like pedal osteitis and frequent fracturing of the edge of P3.
 
The centre of P3 is the thickest part – the hoof should support this area, directly under the roof of the collateral groove.  By removing frog and bar material, there is no longer support under the centre of P3 so the foot has to be supported another way.
 
When the foot is loaded peripherally – on the hoof wall – all of the horse’s weight is on the hoof wall.  P3 is being suspended from the laminae/hoof wall.  RB believes that the hoof wall should support only 5-20% of the horse’s weight, the other 80-95% should be supported by the solar structures, i.e. the frog, sole, bars and dirt plugging the collateral grooves and sole which will support the centre of P3.  “The coffin bone really shouldn’t be suspended from the hoof wall by 100% of the weight.”
 
People think the horse’s weight should be suspended from the hoof wall because when a horse develops laminitis, the laminae can no longer support the horse and it appears that P3 comes through the bottom of the horse’s sole - but actually the hoof is moving up the leg. 
 
There is a large surface area of laminae, and if the foot is trimmed so that the hoof wall is below P3 (the sole), P3 IS suspended by the hoof wall.  But if the foot is trimmed so that there’s minimal weight load on the hoof wall, P3 is not suspended by the laminae/hoof wall, and most of the weight will be on the solar surface of the foot.

RB has seen a lot of pathology in horses’ feet where the hoof wall is the loading structure and P3 is suspended from the hoof wall – the foot adapts to try to minimise stress on the connective tissue.
 
In other mammalian species, e.g. ruminants, camelids, the nail (hoof wall) is not the primary loading structure – they walk on some sort of solar pad.  The horse has a more keratinised solar pad and a very large digital cushion which contains a lot of ligaments and blood vessels – when the foot is loaded, the blood vessels become engorged and remove the energy/vibration of impact.
 
You should be able to pass a ruler under the hoof wall all the way around – the weight should be on the solar part of the foot.

PR made foot imprints as horses left an arena, cleaned the dirt plug out, and the area where the foot was loaded on the arena was inside of the hoof wall.
 
It is thought that P3 doesn’t have a periosteum.  This depends on how the foot is loaded.  If loaded from the hoof wall the connective tissue overlying P3 (the periosteum) changes orientation so that it is no longer parallel to P3.  When the solar surface is loaded, the periosteum is present.
 
RB believes that P3 wants the majority of its weight to be loaded (supported) from the solar ground surface rather than the hoof wall.

NOTES
​Using Dopler ultrasound, able to show that perfusion of the foot changes with the surface the horse is standing on.
 
On a hard surface the same amount of blood is going to the foot, but it stays in the larger vessels.
 
On a conforming surface, small blood vessels become perfused which leads to greater blood flow through the entire dermis of the foot and the internal parts of the foot.  Softer conforming surfaces increase perfusion of the foot – studies in humans have found conforming surfaces “more comfortable” and “relaxing”.
 
RB believes the horse may relax psychologically as well as physiologically when standing on a conforming surface.
 
The footing should be firm, e.g. pea gravel or larger gravel.  Pasture probably isn’t sufficient for stimulation.  In other species on harder (gravel) surfaces bone density increases in the foot and the digital cushion becomes more fibrocartilagenous on pea gravel/gravel rather than pasture.
 
There is no exact distance a horse has to travel – one herd in Canada averaged only 0.5 km/day.
 
Optimal hoof health = the hoof wall bearing only 5 – 20% of the horse’s weight, 80 – 95% of the horse’s weight being born by the solar structures (frog, bars, sole) – this will set up a decent foot.  It’s not about distance travelled, but ground contact, suface, degree of hardness are all components of the whole formula

​​Hoof Anatomy with Professor Robert Bowker - Part ​5 Trimming the feet - EponaTV

NOTES
The digital cushion contains tiny blood vessels which make up a kind of hydraulic shock absorption mechanism.
 
General recipe for trimming:
 Take a marker pen and mark outside the white line.  Trim the hoof wall at 45’ to this line.  You should be left with the pen line, the white line, sole, frog and bars.
Over 100 years ago it was advocated not to touch the sole, frog, bars under any condition.
Feet are very adaptable, the foot will adapt to the environment.
Keep the toe short, bevel walls, lower heels to the level of the frog.
Foot should be 2/3 frog, 1/3 in front of frog.
Farrier shouldn’t touch the bottom part of the foot at all.
 
Why do horses become sore when shoes are removed?
Shoes make the foot less sensitive to the ground.  When the shoe is removed, the foot is much more sensitive to the ground surface – this sensitivity isn’t necessarily pain.  It should take a few days, no more than a week, to accommodate.
 
When the shoe is removed, don’t trim the foot apart from rasping the peripheral parts, and see what happens.  If sore for more than 4 – 7 days, look for bacterial/fungal infections, examine the foot for pathology.
 
Use boots to protect the foot, keep the horse on a conforming surface e.g. sand, pea gravel, deep dirt.  Avoid hard surfaces, allow the horse to adapt and see what happens.  (NB this may assume a foot with no known pathologies before shoe removal).
 
Horses shouldn’t be sore for months after coming out of shoes.
 
They could be sore because of thin soles, so protect the foot with boots and pads or keep the horse on a conformable surface.  If the sole moves when finger pressure is applied in front of the apex of the frog, the sole is thin.
 
There are natural fluctuations in the morphology (shape) of a healthy foot over time, e.g. the thickness of the sole changes particularly with humidity – in dry conditions the sole becomes flatter and firmer.  Don’t trim this – this is the hoof protecting itself.
 
In a normal hoof, regularly check the temperature of the dorsal hoof wall.  Heat could indicate an abscess.
 
Take the digital pulse – a soft pulse indicates good perfusion of the foot.
A bounding pulse suggests more resistance inside the foot and is not good. 
When you trim feet, the digital pulse should become softer.
 
RB said owners can rasp their horses’ feet in between professional trims.
A pretty foot does not equal a healthy foot.
 
A healthy foot has a very dense P3, with lots of robust ligaments – fibre ligaments have changes to fibre- cartilage.  There should be lots of blood vessels through the frog and back part of the foot to help remove energy. 

​These tissues develop as a result of stimulating the solar part of the foot.  The front part of the frog is crucial – by trimming the frog  you decrease the ability of the frog to develop a good internal foot.

NOTES
RB sees many P3s with varying degrees of osteoporisis (OP) – bone loss.
Toe clips apply pressure and lead to reduced bone density.   As do nails.
A crena at the front of the foot is normal.
Holes in P3 are not normal but are common.
Larger holes are vascular channels and normal.
 
The calcium in P3 is replaced every 5 years so the structure can change over a period of time.  So an osteoporotic P3 can increase in bone density by loading the foot from the solar surface and with movement.  The back part of P3 will also lay down more bone and become more dense.

NOTES
​20 – 30 years ago research showed that when a horse is shod and moving on a firm surface, the vibration energy is very high – 2,000 – 3,000 MHz – this is much less if the horse is barefoot.  Vibration energy does not attenuate from the distal to the proximal hoof, and it has a deleterious effect on tissues.
 
If vibration energy is greater than 300 – 500 MHz, this causes blood vessels to constrict - 15 seconds of exposure to this level of vibration caused blood vessels to constrict for 3 days -  this destroys the tissues inside the foot, e.g. a shod horse trotting on a hard surface e.g. a road.  Pads between shoe and foot attenuate vibration to varying degrees.   A shoe loads the hoof wall 100%, RB believes most of the horse’s weight should be on the solar surface – a question of biomechanics.
 
The problem with shoes isn’t that they prevent the hoof expanding and contracting, the problem is the vibration.  Research in Denmark concluded that shod horses shouldn’t move above a walk on a hard surface.
 
Don’t pick out the feet before riding – the dirt plug increases the weight bearing area and acts as a cushion and support for the solar surface of the foot, removing the dirt plug increases peripheral loading.
 
Won’t horses get problems with e.g. thrush if the feet aren’t cleaned out? Thrush is caused by an opportunistic bacteria – if the hoof is functioning correctly and the back part of the foot is stimulated, thrush is less of a problem.

Article edited April 2020 to add:
Dr Robert Bowker talks to Wendy Murdoch of Sure Foot Equine Stability Program April 2020 - parts 1 and 2.

It's not just laminitis that can lead to solar penetration - sadly it isn't rare for vital sole material to be removed during trimming - healthy sole should NEVER be removed within 10 mm (ideally 15 mm) of the bottom of the collateral grooves - see Understanding the Horse's Sole (particularly the explanation of the 2 x-rays 2/3 into the article), and Recognizing Coffin Bone Rotation by Pete Ramey.  

In his article "Sinking Coffin Bones", Pete Ramey questions the idea that P3 pierces through or penetrates the sole, pointing out that the sole grows from the bottom of P3, i.e. it is connected to the bone.  He suggests that instead of believing that P3 has penetrated the sole, we should ask why the sole is missing - "did the corium abscess and allow the sole to fall off? Did someone cut it off? Did it wear away? Has it failed to grow?". 

Prevention
Every step should be taken to prevent solar penetration.  On page 351 of Care and Rehabilitation of the Equine Foot, Pete Ramey says "At the first signs of laminitis, restore P3 to a more natural ground plane, relieve pressure on the walls, and pad the sole with foam rubber – vertical sinking and destructive pressure to the solar corium can be prevented”....."Do not wait.  Immediate action to eliminate constant pressure on the solar corium and separational forces on the laminae and the coronary papillae can be more important than anything else you do."

See Sole Support and EVA foam pads for suggestions for padding the soles.

Trimming 

Trimming the foot with P3 penetration of the sole is not particularly different to trimming any foot with rotation:

• restore the palmar angle to normal and provide a good base of support at the back of the foot, encouraging the heels, frog and bars to bear the horse's weight. 
• remove the detached wall in front of P3 from weight bearing and further separation, by bringing breakover back to just in front of the perforation, without invading true sole, and beveling the outer wall.
• protect the sole (never remove true sole material in the front of the foot) and relieve pressure on the exposed area with padding, possibly with an air hole directly beneath the rim of P3.

See Laminitis and the Feet and Recognizing Coffin Bone Rotation.  Well marked lateral radiographs should always be taken to guide the trim, but if not available, as the sole grows from and is an extension of the bottom of P3, everything behind the exposed P3 is likely to be sole, and everything in front is likely to be laminar wedge/toe.  Collateral groove depths should guide the trim.

Treatment​

Horses with solar penetration will usually require soaks and/or poulticing and/or topical applications to prevent or treat infection in the foot, and the feet may need to be kept covered.  Baby nappies (diapers) can be useful for draining exudate away from the foot and providing cushioning.

Several professionals report good results from soaking solar penetrations with CleanTrax (available from Equine Podiatry Supplies in the UK).  CleanTrax contains a proprietary hypochlorous compound which is non-necrotizing and has no adverse effects on normal, healthy cells but eliminates infection from bacteria, fungi and spores.  CleanTrax is used on humans to treat deep-seated nail infections and on open wounds/surgeries to eliminate the risk of secondary infections.

Other treatments suitable for sub-solar abscesses should be suitable for treating P3 penetrations, such as White Lightning, 50% apple cider vinegar:50% water, warm water and Epsom salts (magnesium sulphate) - see Abscesses.

5 of the 14 horses in Dr Debra Taylor's published rehabilitation protocol had solar necrosis/prolapsed solar coriums (all of the horses recovered).  Their soles were treated with topical tetracycline and/or metronidazole.  During periods of active abscess formation and/or drainage of exudates from the sole, owners were advised to soak the feet 3 to 5 times weekly in either magnesium sulfate solution or 50% acetic acid solution (TLS comment: we suspect this means 50% apple cider vinegar:50% water solution).  
See: 2.6. Management Protocol: Medication
Taylor D, Sperandeo A, Schumacher J, Passler T, Wooldridge A, Bell R, Cooner A, Guidry L, Matz-Creel H, Ramey I, Ramey P
Clinical Outcome of 14 Obese, Laminitic Horses Managed with the Same Rehabilitation Protocol
Journal of Equine Veterinary Science Volume 34, Issue 4, Pages 556–564, April 2014 


With every case of laminitis, it is essential that the cause has been correctly identified and removed/treated, as well as that the feet are correctly realigned and supported.  See Laminitis, EMS or PPID - start here.
For help and support, join Friends of The Laminitis Site.

Raffi had endocrinopathic laminitis and her pedal bones were threatening to penetrate her soles.  
"Trim was applied to realign the hoof capsule and internal structures using Soft Ride Boots. Her feet were soaked in Clean Trax and wrapped in diapers inside the boots until risk of sole penetration and infection was minimal. Then glue/composite shoes were applied.
Exercise: Turnout in dry lot paddock with continual access to deeply bedded stall, no forced movement."

Whisky had pedal bone penetration on all 4 feet.  He was sent to Andrew Bowe at Mayfield where he was trimmed weekly ("heels lowered to get frogs weight bearing and hoof wall totally relieved from any weight bearing responsibility"), his open wounds soaked daily and poulticed when necessary.
Andrew Bowe - www.barehoofcare.com

Blossom, a Clydesdale, had pedal bone penetration.  She was sent to Andrew Bowe at Mayfield where her feet were trimmed to remove the walls from weightbearing, had daily saline soaks and were protected with nappies and padded hoof boots.  She returned to being ridden.
Andrew Bowe - www.barehoofcare.com

Zara had pedal bone penetration on 3 feet.  Her feet were trimmed, cleaned, disinfected and dressed and supported in hoof boots, before she was sent to Mayfield for rehabilitation.  9 months later she was returning to work and galloping in her paddock without pain.
Sarah Kuyken - www.iskanderrun.com.au

Glynn had pedal bone penetration on all 4 feet.  His feet were trimmed regularly (initially every week) and padded and bandaged.
Cynthia Cooper - www.naturalhorseworld.com

Druid had pedal bone penetration on all 4 feet, with sinking at the coronary bands and abscessing. 
Paige Poss - www.ironfreehoof.com

Monroe, a pregnant sports horse broodmare, had pedal bone penetration on both front feet following an infection.   

More information

Reading Sole Thickness - Pete Ramey Horseback Magazine June 2013

Why Does My Horse Have a Thin Sole? - Pete Ramey Horseback Magazine July 2013    

Understanding the Horse's Sole - Pete Ramey

Clinical Outcome of 14 Obese, Laminitic Horses Managed with the Same Rehabilitation Protocol