Connections between angle of the shoulder and pain in the hooves — a contribution to diagnostics of lameness

Dr. med. vet. Hiltrud Strasser

Abstract

The body posture of a horse is defined by the positioning of the hooves and limbs, the angle of the shoulder, the height of the withers and croup and the profile of the backline.

In the horse world many faults in conformation are considered genetic and irreversible. This research demonstrates that there is a link between pain in the hooves and conformation and body posture, and the problems are, to a certain extent, reversible when the cause is removed.

The 60 documented cases illustrate the connection between hoof capsule deformation and body posture. Shoulder angles were also assessed in anatomical drawings and photographs found in farriery, veterinary and horse breeding textbooks and in naturally living, wild horses. Removing the cause of the pain in the hooves resulted in a significant change in shoulder angle, approaching what would be considered the normal range as evidenced from the textbooks and wild horses. This observation of shoulder angles is a useful diagnostic tool indicating hoof pain.

Materials and Methods

Observations over many years, which included hundreds of horses identified with locomotory problems, indicated that the angle of the shoulder was steeper before trimming hooves, with our method, than after. This suspicion resulted in the scientific documentation of 60 cases. The horses were led around and allowed to assume a comfortable position. Lateral photographs were taken at a 90° (degree) angle to the sagittal axis. (See Figure 1.) Measurement inaccuracies can be made when the angle of the photograph is not precise however consultation with statisticians confirmed that these errors become statistically insignificant due to the large number of cases.

The highest point of the wither is located and a vertical line drawn down from this point to intersect the ground perpendicularly. The frontal aspect of the point of the shoulder is then identified and a line drawn connecting this point to the highest point of the wither. A horizontal line is then drawn from the point of the shoulder to the vertical line intersecting it at 90°. The shoulder angle (a) can be determined. (Figure 1.)


Figure 1. — Determination of the shoulder blade angle




Figure 2a and b. — Comparison of shoulder angle before and after hoof treatment.

Measurements were taken from the skeletal drawings in 10 different textbooks from various countries and written in varying time periods. (See Figure 3.)


Figure 3. — Measurement of shoulder angle from textbook pictures.

Shoulder angles of patients:



Shoulder angles averaged 61.5° before trimming and 57.3° after trimming. An average reduction in the shoulder angle of 4.2° was calculated. 30 (50%) of the patients were considered higher in the quarters than at the withers before trimming. After reducing the overgrown bars half of those affected were observed to have lost this conformational deviation.

When a vertical line was drawn from the highest point of the withers to the ground it was found that this line transected the humerus in most of the patients (indicating the line was cranial of the elbow joint), however after the first treatment only 33% still exhibited this abnormality. Only 3 patients (5.0%) had vertical cannon bones before treatment. After trimming 48 (80%) of the patients had vertical cannon bones. (See Figure 2a and 2b.)

Shoulder angles assessed in

a) Anatomical textbook pictures:
1. Hickmann ............... 52°
2. Körber .................... 52°
3. Adams .................... 58°
4. Nickel/Schu/Sei ...... 52°
5. Wissdorf et al .......... 56°
6. Goody ..................... 53°
7. Gray ........................ 50°
8. Rooney .................... 54°
9. Lungwitz ................. 49°
10. Ruthe ..................... 47°
Average ....................... 52.3°

b) Photographs from a horse breeding textbook “Pferdezucht und Pferdefuetterung”:
45°
45°
51°
47°
47°
Average 47°

c) Photograaphs of Exmoor Ponies “Survival of the Fittest”:
47°
49°
Average 48°

d) Photographs from auction catalogues of champion horse:
53°
54°
51°
55°
50°
52°
Average 52.5°

It can be assumed that wild horses and top class breeding horses have good anatomical conformation and therefore optimal shoulder angles. The author has not identified a shoulder angle greater than 55° in these groups. In the older textbooks it was not possible to find a shoulder angle greater than 53° but in the newer textbooks, (Adams, Wissdorf) shoulder angles of 56-58° are common.

Results

1. The shoulder angle in healthy horses is between 45° and 55°.
2. Our patients had on average an 11° greater shoulder angle (61.5°) than what is optimal (50°).
3. Most of the patients with non vertical cannon bones before treatment had vertical cannon bones after treatment.
4. A significant number of horses assessed as high in the quarters assumed a normal body posture after treatment.

Discussion

The thorax is suspended between the shoulder blades in an elastic way by different ligaments and muscle systems. The highest point of the withers contour is a spinal process and this is connected to the other spinal processes and also to the shoulder blade by the pars cucullaris of the lig. Supraspinale (“cap of the wither”). This point is in alignment with the dorsal end of the shoulder blade and is kept this way via the connection described; consequently it can be used as a reference point. (See Figure 3.) A line from the shoulder joint to the highest point of the withers runs parallel to the spine of the scapula and m. supra spinatus and can be used to represent the angle of the shoulder blade. (See Figures 1 and 3.)

It is assumed that wild living horses and top breeding horses have optimum shoulder angles. (See figure 1.) The investigation found no shoulder angle steeper than 55° in these groups of horses. A consideration of all of the measurements in the study leads to the conclusion that there is an anatomically defined optimum shoulder angle of approximately 50° (ranging from 45° to 50°) and it can be assumed that the steeper shoulder angles commonly seen today are pathological. It is noteworthy that more recent veterinary textbooks have illustrations showing steep shoulder angles as anatomically normal. This may be caused by the (unfortunately) widespread acceptance that steep shoulders are correct.

The stay apparatus of the horse has been well documented and notable anatomy textbooks in all languages illustrate the stay apparatus with ground parallel coffin bones. A standing horse with correctly suspended, ground parallel, coffin bones exerts no energy, and does not need muscular activity, to support its body weight. (See figures 3 and 4.) It is obvious then that the muscles of a quietly standing horse are smooth and soft.

The angles between the bones in the limbs of a horse are fixed by the tension between the two tendon systems (flexor and extensor) — see Figure 4. Changing the angles of the joints from that which is optimal requires muscular activity. When the coffin bone is displaced from the ground parallel position a necessary muscular adjustment is made by the horse to regain a balance in the tendon systems – this muscular activity is not designed as a long term solution as a knowledge of histology explains. Unfortunately current attitudes ensure that this situation is ongoing, resulting in chronic muscular tension. These contracted muscles can be seen by the well trained eye as bulging and can be palpated, being hard and undeveloped. Well developed muscles, through training, may also look bulging but do not feel hard. Muscle tension in the limb of a quietly standing horse is not a healthy situation.


Figure 4.

Steepening the shoulder blade requires the action of various muscles namely m. rhomboideus, cervical part of m. serratus and the m. pectoralis profundus and it is primarily these muscles that become chronically contracted. What reasonable explanation can there be for why an animal, so well designed to operate efficiently, activates an energy consuming muscular system to steepen the shoulder?

Hundreds of observations of shoulder angles and the changes obtained from the trimming method used prove that the main cause for unphysiological muscular tension is pain in the hoof. Removing the cause of hoof pain, by trimming, results in should angle changes from the pathologically steep towards the more physiologically correct. As it is the long heels and overgrown bars that are removed it is logical to conclude that these are responsible for the pain, muscle tension and steepness of pastern and shoulder angles. (See Figure 2a and 2b.) Pain in the hoof, in most cases, is caused by long heels and overgrown bars.

There is a direct connection between the pastern angle and the shoulder angle due to the indisputable necessary balance between the opposing tendon systems. Today nearly all horses, including young horses, are trimmed with long heels consequently the sensitive internal areas of the hoof receive unphysiological pressure during weight bearing. To minimise or prevent this pain, the horse keeps the pastern steep by using fore arm, shoulder and neck muscles in order to avoid loading the area of the hoof which is being subjected to the unphysiological pressure. The horse will weight the frontal aspect of the hoof avoiding the posterior heel area which is painful. These actions result in the stance commonly seen in our patients. Rearward slanting cannon bones can be quickly identified by visually dropping a vertical line from the highest point of the withers to the ground. (See Figures 1–4.)

When the problem is unilateral lameness is obvious however when the problem is bilateral then the movement is stunted or stiffened and overt lameness is not readily identified. It is regularly observed that the paces of the problem horses we have treated improve. The lameness does not immediately disappear due to inflammation in the previously pinched areas, which takes some time to resolve depending on how severely damaged the corium is and on how chronic the situation was. The healing process will frequently involve abscessing of necrotic material that resulted from impaired circulation to the front of the coffin bone. (Pollitt video 1993 clearly shows the occlusion of the digital arteries that occurs with the elevation of the heels). This is removed by the return in blood circulation associated with ground parallel coffin bones.

Conclusion

Significant changes in conformation have been observed after trimming the bars and heels of patients presented at the Hoof Clinic. This finding has been evaluated by the scientific measurement and comparison of shoulder angles as outlined in this report. In horses with locomotory problems the angle of the shoulder can give an indication of where the pain is located however it is important to be familiar with the effects of the muscles and their synergistic relationships so that a correct diagnosis is made and appropriate treatment programme implemented.

The observation of a vertical line from the highest point of the withers to the ground can provide an initial indication of tension in the musculature of the flexor apparatus. This can be confirmed by palpation and determination of the shoulder angle. Without even lifting the hooves it is possible to diagnose whether an animal suffers from pain in the heel/bar area.

___________
Literature

Amirsadeghi, H., “The Arabian Horse”, British Library Cataloguing, in Publication Data, 1998
Baker, S., “Survival of the Fittest”, British Library Cataloguing, in Publication Data, 1993
Goody, P., „Horse Anatomy“, J.A. Allen, London 1976
Gray, P., “Lameness”, J.A. Allen, London, 1994
Hickmann, J., “Farriery”, J.A. Allen. London, 1983
Koch, T., “Lehrbuch der Veterinär-Anatomie”, Gustav Fischer Verlag Jena, 1960
Körber, H.-D., “Huf, Hufbeschlag, Hufkrankheiten”, Kosmos, Stuttgart, 1997
Löwe, H./Meyer, H. „Pferdezucht und Pferdefütterung“ Eugen Ulmer Verlag Stuttgart, 1979
Lungwitz, A., „Der Lehrmeister im Hufbeschlag“, G. Schönfeld's Verlagsbuchhandlung, Dresden 1896
Nickel, R./Schummer, A./Seiferle, E., „The Anatomy of the Domestic Animals“, Parey Berlin, 1986
Rooney, J.R., “The Lame Horse”, The Russell Meerdink Comp. Ltd, WI, USA, 1998
Stashak, T.S., “Adam ́s Lameness in Horses”, Lea& Febiger, Philadelphia,USA, 1989
Storch, A., „Zar Konj” („König Pferd“), Quadratisch Print Design, Moskau, 2003
Strasser, H./Kells, S. “The Hoofcare Specialist's Handbook”, Sabine Kells Publishing, Canada, 2001
Wissdorf, H./Gerhards, H./Huskamp, B. “Praxisorientierte Anatomie des Pferdes”, Verlag M&H Schaper,Alsfeld-Hannover, 1998

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Human Playground

by Berenika Bratny, Wolne Konie

As humans we have to learn all our lives. How to survive, how to communicate with others, how to have a happy relationship, how to express our emotions.

In order to train ourselves and our children we need a playground. Before we go into our adult lives we have to practice our emotions first — to try all we know on someone — animals.

Animals are human playground. It is good to have a pet for a child, many say, as it helps him to socialize with people later, as it teaches him to be responsible. As it gives the joy and sorrow of relationship.We experience the love of our pets, we learn how to take care of them, and others, too. We experience the sadness and the grief of illness and finally — the death saying farewell to them when their time comes.

Let’s be honest — we also practice killing. It might be the direct experience (how does it feel to kill a toad, a snail, a mouse? How does it feel to see a chicken killed by your grandmother?) or we might practice it as a denial (where do those lovely little piglets and calves go?).

The ways we treat others is often the result of what we have been taught by the use of animals. We build a wall between us and the rest of the nature (and animals), we learn how to kill, how to control, how to use and how to discard what is “useless”. We do it all the time with all kinds of animals. And we are still surprised that our lives are getting worse and worse, we loose communication with one another, we loose contact, we loose the ability to love. But do we practice love? Do we practice compassion? Our playground is often to practice kill and misuse, to experience terror, fear and power, nothing more.

How many times do we see a young boy “madly in love with horses” who carries a whip with a proud smile on his face? Or cute little girls with pink helmets tugging on the reins of their ponies? My friend’s 12 years old son was so crazy about horses that she bought him one. Beautiful sorrel mare. I was the “aunt who has horses” so when I paid a visit I was literally dragged to the nearby stable to see “the love of his life”. We entered the clean sport stable, all horses locked in their stalls. Sorrel beauty was lying asleep. We stood for a while in front of thick bars and looked at her. “Isn’t she beautiful?” — he whispered. Then opened the door and... kicked her. When I asked him about it he said he did it because she has to stand up when “her master is coming”. This is what he has been taught already. This is how he expresses his feeling of love. Do you think you’ll be surprised if, ten years later, he would have problems with his girlfriend? How would he express his feelings? Will he respect her? Or is it a cruel beginning of an emotional life full of misunderstanding and pain?

As children we really love our pets, how could we not? They are so cute and nice, they share our sorrows and happy times, they are our real friends. But during that process we are taught by adults how to treat them. And this is especially true with horses. They are big animals, seem dangerous to many, so adults feel the need to explain how to control them. And so the mad circle of sorrow and pain begins. And it does not end when the child grows up and the pony is sold like old shoes which were too tight. The feeling goes with the child into his adolescence and into his adulthood. It is always there, at the back of our minds – does love mean the need to control? Does love mean the need to use? Yes, it does — this is the lesson we are taught by the use of horses.



“What happened to the old mare who taught me the first steps of canter?” — I asked my aunt once. “Well, she was too old to carry a rider so we had to give her away,” — she replied with sorrow. She didn’t know that she planted a seed in my mind and one day, when she will grow old I will feel the burden of her presence and think about giving her to the retirement house. With sorrow, of course.

But there is also the other side. The moment when our emotional lives are such a disaster that we face the wall. The bottom. We realize — either we drown or we try to save ourselves. And then we look at our horses and see them as a mirror of what’s happening in our personal lives — obsession of control, fear of letting go, the lack of ability to trust. We make the first step, the smallest but the most profound — we open our eyes.

The road is long, sometimes dangerous, sometimes we think we’ve lost the way. We struggle with all the things we learnt before, all the reflexes, all the emotions and fears. But one day we will be there. Safe and sound. And saved.



But it could have been otherwise. We could be spared from the torments of emotional pain, misunderstanding and chaos. It could begin early in our lives, the day we get the first horse. Imagine — you are five, the pony you dreamt about approaches you, sniffs your hand and the only instruction you get is to respect it and listen to your heart. Later you’ll be able to experience something which you will express with such words:

“She is not here to follow or to learn from me. She is here to live as herself. When not wearing anything she is most beautiful. Giving her control is what I believe to be my biggest moment as a human. I have never done anything with so much meaning and love before. The gift i got in return was a friend, whom I love and treasure more than anything. She gives me love, but not in the way many wants. She won't follow me anywhere. She won't listen to every command I give. There is no way I can touch her everywhere I want whenever I like, but I know she cares about me and sees me as another living creature. […] When I do my work in the stable she will stand behind me with her head close to my back just nibbling my jacket. There is all those small things nobody else sees that makes me so sure I am important in her life.”
(Jeanette Ludviksen)

Aren’t these words of love? Wouldn’t you like to be loved this way yourself. Imagine…

The Flexion Test

by Dr. vet. med. H. Strasser

The flexion test is commonly applied in lameness diagnosis. Vets have expressed various opinions about the point and value of the flexion test. Unfortunately, nobody has so far expressed thoughts on what the more or less severe lameness can then be attributed to. In my opinion, it is important for the horse owner to understand on what principle the test is based, in order to judge the situation and decide whether he wishes to continue using the horse, or is willing to take upon him the cost of treatment.




The situation is as follows:

It is common knowledge that, when bending the toe joints at a certain place, the blood supply to the hoof is interrupted, so no blood flows into the hoof. If there is a painful inflammation in the hoof, the lack of circulation is comfortable, because it disables sensitivity to pain. Above the "tourniquet" location, in the region of the navicular bone and the head of the pastern, congestion develops. When the limb is released and takes up its normal angle, the blood rushes into the inflamed region with increased force (congestion wave), which is even more painful for the horse than normal circulation.

Thus the flexion test gives information if there is inflammation in the hoof area.

At first one does not know where the inflammation is localized. The specialist can draw conclusions based on the shape of the hoof capsule and the way the horse uses the foot as to whether it is a developing hoof abscess, the beginning of coffin bone rotation, or navicular syndrome. Appropriate measures can, in any case, lead to complete healing, so long as the cause is recognized and eliminated.

Copyright Dr. vet. med. H. Strasser

Two cases of the quarter crack in the hooves. What do we learn

Natalija Aleksandrova

Two cases of the ‘incurable’ quarter crack. In both cases, the crack was treated for years by that what exactly had become the initial cause of the problem — the shoeing combined with the unphysiological hoof form (too high heels, too long walls).

Case 1:




Case 2:




On weightbearing, the hoof capsule is supposed to deform in a certain way. This reversible deformation is called ‘hoof mechanism’ and is vital for the whole horse’s organism. (More on the hoof mechanism >>) In the case of these two hooves, the coronet could only bulge outward at the lateral wall but not to move downward (because the sole is fixed by the shoe), as it happens in a physiologically correctly shaped hoof as a part of the healthy hoof mechanism. Over time, an outward crease developed in the wall, starting from the coronet, and right at the last nail, where the weakening of the wall appeared from the hole of the nail. With impact of the hoof contacting the ground, this crease was pushed outward, and with lesser impact (standing on non-weightbearing hoof), the coronet was straightening out somewhat again, drawing the crease flat. This movement prepared the situation for the actual crack to appear, and later it appeared, helped by the weakening of the wall at the last nail hole.

Sadly, the first horse never got a chance to receive the correct hoof care, and ended up in slaughter, giving us now a chance to look closer to the hoof capsule and to learn what certain outward signs suggest about inner hoof structures.

After removing the shoe and trimming the overgrown wall of the cadavier, we are able to see the curve in the while line in the place where the crack starts in the ground contact edge of the wall:



This kind of the curve in the white line suggests, there should be demineralization in the coffin bone in a form of a notch or a groove, which appeared as a result of a certain kind of pressure affected the bony tissue.

Now taking a look inside the hoof capsule, we can see the expected groove in the palmar process of the coffin bone. And we can see the ridge in the inner side of the wall, which was pressing into the bone, causing its remodelling. This is additionally to the more pronounced side bone (lateral cartilage ossification) we see on this side of the bone, caused there by the same reasons as the crack in the wall — the unphysiological forces affecting the hoof capsule and the inner structures:





A similar curve in the white line was found in the second case:



But in the second case, the horse, a warmblood gelding, was luckier. After wearing the shoes for 15 years, prescribed them by vets and farriers as the only remedy against the crack, and bleeding recurrently in the coronet where the crack started from, his shoes finally were removed at age of 18 y.o. and he started receiving the correct hoof care. The correct hoof care began for him from its very important part — providing the horse with species appropriate living conditions, which included free movement 24/7, free access to grazing/hay 24/7 and a herd. His hooves were kept an optimal shape via the physiologically correct trimming, and Nature was able to make the rest via the species appropriate living conditions.

5 months into the rehab, the gelding feels great (the white horse), playing with his buddies:
(Video Ark Equus Ranch for Retired Horses, alHHHC Partner Rehab Center, Germany.)



After 9 months of the rehab, the crack disappeared, the hoof still is improving its shape:



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