Questions about jam's and shears

["Riddle"]

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[Ronald Aalders]

Good question Mrs. Riddle!

Before sharing my views on this, for all their worth, I'ld need a better description on what you define by shears and jams.

Would a shear be a crack? Or are you thinking of heels here? A jam would be a wall rolled in? Or a dish in a wall? Or are you refering to heels here also?

Maybe some pictures would help get us all off at the same point.


Ronald Aalders

[Phil Armitage]

Good questions, I am going to answer them by explaining how I dealt with this issue on 2 horses, barefoot and by shoeing and what I saw along the way. Give me time to get it down on paper. Makes a good essay to work on.

[Donnie Walker]

Riddle - for a thorough understanding of "sheared heels" go to the following web site - www.equipodiatry.com - search under the title "podiatry" and you will be able to read some excellent information compiled by
Dr. Stephen O'Grady, DVM/Farrier.

[calshoer]

I would like to hear other farrier's thoughts on this subject. I will ask some questions that I would appreciate your knowledge and opinion on.

1. Reasons a jam is caused or created

2. Reasons a shear is caused or created

I assume you mean something diferent by 'Jam' and 'Shear', so clarification of your definitions would help but for now I am going to just address "shear", in reference to heel bulbs. A sheared heel occurs when the coffin bone is not level to the ground medial-laterally for a period of time. (This un-level of the bone is usually due to too much hoofwall on one side of the foot beyond the bone and sole plane (common with the use of Tsquares on imperfectly conformed horses) ;) When the horse's weight loads the unlevel bone , the bone will try to be pushed level to the ground simply due to the weight above. Something HAS to give.The bone cannot shift medial laterally much relative to the bones above it without causing joint damage and pain , but the hoofwall can sure bend easier, laminae can shear, and heel bulbs can move. So as the bone settles on the high side trying to level, the hoofwall shears up on that side,as the bone slides down past the wall. The heel bulb goes up with it, meanwhile the other side of the capsule flares.


3. What are the distinquishing characteristics of each?

Since I don't know what YOUR definitions are of each, if you describe them you should be describing the characteristics.
Normaly a sheared heel is when one heel is shoved higher than the other heel. As to a "jam", if you refer to hairline distortion, it depends where on the foot.

4. Is the circulatory system in the foot affected? If so, how?

Probably some,but no one knows because there is no good way to test that yet .

5. Do these conditions appear in unshod feet? If so, why?

Answering as to sheared heels only, Yes. If the feet are left unmanaged and grow excesively long, the hoof capsule will begin to bend somewhere. Long hoofwall anywhere on the foot is always one of the culprits in hoof distortion.Short hooves, trimmed or worn to the sole plane evenly all around the foot will not allow shearing to happen even in very poorly conformed horses.

6. Does the hoof capsule compensate differently in reaction to these
conditions if shod or un-shod? If so,how?

I think they react more rapidly in shod horses because a bare foot can at least wear back into internal balance if given the chance on hard ground. An unbalanced shod foot is stuck with what the farrier gave it.

7. If a foot has both a jammed and sheared area is one area likely to grow
more rapidly? If so, Why?
Idont thinbk one area grows more, it just becomes distorted or compressed in different areas. If you look at the .growth lines very near the coronary band inNONlaminitic horses, they begin fairly evenly, then get uneen the lower they go on the foot.

how do you remove these conditions?

As to sheared heels, the cure is first INTERNALLY balance the foot, via getting the coffin bone level to the groung medial laterally. Trimming tot he sole plane has proven so far to be the most accurate way next to Xrays.
As to 'jammed' feet, if you mean coronary band jams , there are several different factors creating diffeent kinds of jams so you need to be exact in where the jam is to discuss causes and cures. Patty

Any other thoughts you find important to understanding and dealing with these conditions are welcomed. I have seen other posts where these conditions have been touched upon. I think this area can be confusing to many. A thread devoted to understanding, distinguishing and dealing with these conditions would be interesting and I am sure helpful to many.

Thank You

["Riddle"]

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[Jason Maki]

A whole thesis could be written on this subject, and Riddle gave a good start. In general, a think of a shear occuring in the back half, wear the horn is attached to soft tissue, thus can twist easily. A jam is a compression of the horn and the coranary region, which is attached to horn via the laminae, thus cannot twist, but only compress.
Jason Maki CJF

[Phil Armitage]

• Two Horses I do came to mind when I first read this thread, Horse #1 is a TB Jumper who fell into the Jamming Category. This horse was on and off lame and constantly pulled shoes. My first observations were stress rings on the medial side of both front feet and slight flares on the lateral side and dish in the dorsal wall. All signes of poor balance and stress. The sole was thin gave to thumb pressure in the toe and the bars were very weak and no toe callous. The first couple of shoeings I trimmed to the sole plane to fix the medial/lateral balance issue and did not touch the sole in the toe. Used a straight bar shoe with Equipak for support and protection. After a couple of shoeings the feet improved dramatically and this horse is now in regular shoes, staying sound and not pulling shoes anymore. I believe the Jamming was caused by poor trimming, the previous farrier invaded too much sole and was not able to see balance anymore and over time the feet became weak and got away from him, the horse pulled shoes from being sore. Horse #2 was a Saddlebred with built up feet and weighted shoes, came to me during the off season to basically pull the shoes and trim for the winter, the owner mentioned that her horse was always off and nobody could explain why. :confused: I showed her the heels and that they were sheared, basically the shearing was caused by long heels that were not balanced, no frog or sole support and needed to be corrected. She let me reshoe the horse this summer, I trimmed to the sole plain, applied shoes with a Myron Maclaine frog support pads and Equipak for support. The bulbs are just about level and the tearing between the cleft of the frog is almost healed. Unfortunately this problem was there for a long time and the RF looks like there is permanent damage internally and it is not healing as well in the cleft of the frog. The horse is moving much better since I balanced the feet with a good trim and added support and protection.

• My definition of shearing is when one heel and bulb is pushed up and there is tearing and separation in the cleft of the frog and bars are weak/broken. I have found the rear portion of the foot to be too flexible and there is lameness.

• I am not too sure what you mean by Jamming, however what comes to mind is where any portion of the hoof capsule is pushed up and pushes the corronett up with it. Deformity of the hoof capsule, flares, cracks, bulges and any type of stress on the horn, sole and bars.

• I see this as symptoms of stress and pressure on the hoof capsule and can be caused by many things, poor trimming, lameness, environment, conformation or nutrition.

1. Reasons a jam is caused or created. Improper trimming, neglected feet, poor nutrition, excessive moisture or lameness.

2. Reasons a shear is caused or created. I think shearing is primarily caused by improper trimming.

3. What are the distinguishing characteristics of each? Shearing is one heel pushed up where one bulb is pushed up high enough that it tears the cleft of the frog and weakens the bars. It is also very painful. Jamming is where there is where the horn is deformed; the corronett could be pushed up, flares, cracks curling and/or bulges.

4. Is the circulatory system in the foot affected? I believe it is. If so, why? Jamming and Shearing can cause pain and when a horse feels pain, they compensate and do not land properly which compromises how the hoof functions.

5. Do these conditions appear in unshod feet? Yes, I have seen it. If so, why? Poor trimming, poor nutrition, poor conformation, hoof diseases, excessive moisture, neglected feet or filthy stalls.

6. Does the hoof capsule compensate differently in reaction to these conditions if shod or un-shod? Yes the hoof capsule does react differently to these conditions shod or unshod. Both conditions can be improved by going barefoot with proper trimming done on a regular schedule, however depending on how severe the condition is and thickness of the sole, I have found if going barefoot the horse might be unusable and the repair process is slow. Even when addressing the problems by shoeing it is still possible that the horse is unusable, however the heeling process is quicker. This all depends on how severe the problem is, I will use a bar shoe and/or frog support depending on condition of the frog. A bar shoe relieves the stress and pressure on the affected heel or jamming. Usually a good trim will fix most jamming problems. Sheared heels, can be more difficult and require unloading the heels, by floating the heel and sharing the load by using bar shoes, heart bar or frog support pads, impression material or Equipak. Going barefoot also helps to distribute the load; however in many sheared heel cases in wet environment you will find the heels and frog may be too sore to go without proper shoeing and thrush becomes a major obsticle.

7. If a foot has both a jammed and sheared area is one area likely to grow more rapidly? Yes, because the horse will compensate for pain and the portion of hoof with less pressure will grow faster.

8. How do you remove these conditions? Well I think I have answered that in the other questions, starting to feel redundant, proper trimming and/or shoeing to eliminate stress and pain.

[Stephen E. O'Grady, DVM]

Phil

We are going to look at this topic at the Hoof Care Summit. Hope you can make it.

Stephen E O'Grady, DVM

[Phil Armitage]

Wish I could, but unfortunately I won't be able to. I was planning on it, but I have spent to much money and time away from home this past year, and my wife has drawn a line. Hopefully next year. Geesh you would think the wife would be more understanding :D

["Riddle"]

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[Stephen E. O'Grady, DVM]

Interesting thread! Until proven wrong, I must condider shearing (sheared heels) and jamming one and the same.

Stephen E O'Grady, DVM

[T.N. Trosin]

That and farrriers cause low heels in thoroughbreds right Doc?
What in the world? How about an answer? Your a Vet for crying out loud. Give me a couple of days on this. I need Pictures, and it's raining here.
I think I can answer this, probably not as elequntly as Riddle worte his post.
But I know what he means

[Jason Maki]

Riddle,
Very interesting, but i will need to read that a few times before I can utilize any of the info. Rapid assimilation of complex information is not one of my strong points!(However artistic allitiration erupts effortlessly :rolleyes: )
My working definition of a 1/4 crack IS if it is subsequent to a sheared heel. I see lots of, for lack of a better word, hoof flaws that are simply injuries, seperations or cracks within flares that are not the result of the hoof capsule splitting under pressure. This may be within your realm of thinking( I still have not grokked( A fictitious word coined by Robert Heinlien meaning assimilate and fully utilize in all possible aspects) your thinking, so i may have missed it.
The hoof is three dimensional, moving not only in and out, but up and down as well. When the lateral toe is jammed up, the medial heel is overloaded, and displaces upwards untill the weight bearing plane is level with the basil surface of PIII. The attachment to the lateral caritilage allows for this flexion. The tissue is damaged in this level seeking. The vascular supply is impinged, laminae are torn, and cartilage will ossify, due to thrombosis. I think the hoof pops a 1/4 crack when the force up on the medial heel and lateral toe displaces the horn and cartilage past its tensil strenght at a point just palmer to the bridge of the foot. This horn from this point forward is unable to twist, and the twist, or shear causes the horn to pop to releive the stress. I will unload the foot in this case from the medial bridge to the buttress, and from the center line lateral to the bridge. I leave all of the horn in the medial toe and lateral heel untrimmed. I then force the horse to load the Roller Coaster foot. Invariably, the medial heel and lateral toe will settle, often to bearing. I then re-trim the foot, but will unload the jammed and sheared sections again. I have never had a shear or 1/4 not dissipate with this system. God bless Randy Luikart who taught it to my teachers teacher, who taught it to him, who, despite my incredulous disbeleif, taught it to me!
I think the loading of the good secions inverts the shearing forces and actually forces the displaced tissue down. If I had the resources I would love to do a venogram on a sheared foot before the diagonal trim, then immedialty following. I think the re-routing of the blood supply would be amazing! I am know going to re-read your post. I can only hear about every third word someone else says...my prejudices react to what they are saying before my brain has a chance to finish the sentence! :eek: :D
Jason Maki CJF

[Jason Maki]

Dr. Meyers,
Far from being proof, more like my personal working definitions:
A jam is the compression of the horn, which in a way resembles a shock on your truck: a tubular horn, packed with intertubar horn filled and surrounded by intratubular horn. The horn is designed to compress to a degree, but when the tolerence levels are exceeded, or the horn is not permitted to unload, it compresses nad eventually irritates the coranary band.
a shear is the twisting of the horn connected to soft tissue. It cannot compress, because the flexion inherient to its location on the capsule makes that impossible. If the heel region is overlaoded, it simply displaces up en toto untill the bearing plane is correct.
Subtle distinctions, yes, but distinctions in my mind, none the less! :D
Would you agree?
Jason Maki

[Phil Armitage]

After reading this especially Riddles comments, the first thing that came to my mind is why it is important to properly prep the foot with a good balanced trim and allow for expansion by nailing forward of the widest part of the foot and fitting shoes full behind the widest part of the foot and also keep the horse on a good schedule, like 4 to 6 weeks.

[Mike Ferrara]

After reading this especially Riddles comments, the first thing that came to my mind is why it is important to properly prep the foot with a good balanced trim and allow for expansion by nailing forward of the widest part of the foot and fitting shoes full behind the widest part of the foot and also keep the horse on a good schedule, like 4 to 6 weeks.

It's hard to disagree with your basic premis...balance and a regular schedule. Without a reasonable shoeing interval it's hard to maintain balance even if you ever had it. I'm not convinced about the evil of nails behind the widest part of the foot though.

[Ronald Aalders]

I assume you mean something diferent by 'Jam' and 'Shear', so clarification of your definitions would help but for now I am going to just address "shear", in reference to heel bulbs. A sheared heel occurs when the coffin bone is not level to the ground medial-laterally for a period of time. (This un-level of the bone is usually due to too much hoofwall on one side of the foot beyond the bone and sole plane (common with the use of Tsquares on imperfectly conformed horses) ;) When the horse's weight loads the unlevel bone , the bone will try to be pushed level to the ground simply due to the weight above. Something HAS to give.The bone cannot shift medial laterally much relative to the bones above it without causing joint damage and pain , but the hoofwall can sure bend easier, laminae can shear, and heel bulbs can move. So as the bone settles on the high side trying to level, the hoofwall shears up on that side,as the bone slides down past the wall. The heel bulb goes up with it, meanwhile the other side of the capsule flares.
Thank You

This is exactly what happens. This is also why you want to work towards heels of equal height. This may well mean that a distorted foot (a medial heel pushed up, you've seen it more than once) after trim does not point straight forward anymore. While before the trim it did. You should remember that you may be able to get the heels even in one trim, but that the adaption inside the foot takes longer.

Look at the picture posted. If you even out the heels here, that foot is going to twist outward big time. You may reduce this effect a little by lowering the lateral toe, but you won't be able to do much more. Not until the structures inside the foot have adapted to a (hopefully) better stance, the foot will not point straight forward and such a foot will toe out. Not because of a conformation problem, but because of a foot problem.



Ronald Aalders