The Importance of Recognizing Capsular Distortion

The Importance of Recognizing Capsular Distortions Monique Craig

Hoof capsules are designed to adjust – within reason - to external factors. Normal fluctuations in moisture and ground surface require benign adjustments by the hoof. Man-made factors such as hoof care and riding have more profound effects on the ‘normal’ shape and function of the hoof. It is therefore very important to recognize poorly trimmed hooves and understand the potential ramifications for the entire horse.

The hoof capsule is the structure that covers the hoof and is made up of keratin. The keratinized capsule with its complex architecture does much more than just offering protection to the underlying tissues. The walls and bars are capable of shock absorption. The keratinized sole and frog provide the base of support for the entire bony column.

Adverse changes in the keratinized capsule may compromise the health and position of underlying tissues (e.g. the dermis, lateral cartilages and digital cushion). Soft issues may accommodate for the distortions by shifting and/or compressing --- but only so far. With time, the damage will become evident not only to the hoof but sometimes to the entire musculoskeletal system of a horse.

Figure 1: The pedal bone riding on the sole. Top view on the left and a side view on the right. The digital cushion can be seen in the rear part of the foot.

Figure 2: The pedal bone (1) and its epicondyles (2), and the navicular bone (3), with the lateral cartilages (4).

I will use one of my recent case studies to illustrate what may arise from poorly trimmed and shod hooves. The horse ‘’Monte� came to me

mid-March 2015. It is a 14 years old warmblood, height approximately 17.1 hands. He is a show hunter-jumper. A thorough veterinarian lameness evaluation was performed before the first trimming and shoeing session. His frontal hoof radiographs indicated above normal palmar angle on the right front hoof – about 11 degrees; an acceptable range would be between 1 to 6 degrees depending on the shape of the pedal bone. The first lameness examination did not indicate serious lameness issues, just some gait unevenness and overall body soreness.

Figure 3: Body before and after. The ‘before’ picture was taken in March 2015. It was very difficult to stand Monte square. His tendency

was to bring the hind forward. Note the position of his right front limb in relationship to the shoulder point. The ‘after’ picture was taken in May 2015. It was much easier to square Monte, again note the position of his right front hoof in comparison to the shoulder point. These before and after pictures are not precise since there is only so much one can do to stand a horse correctly. However it is always easier to square a horse when the hooves are well balanced!

Monte had another lameness evaluation four months later which indicated a significant improvement in overall comfort and movement.

Monte was then slowly eased back into work. I was very lucky that Monte’s owners wanted the best for their horse and opted to give his body and his hooves a break. This is unfortunately not always the case with show horses! Initially, Monte’s hooves could have served as poster child for hoof issues. All four hooves showed signs of white line disease with notable wall separation.

Figure 4: View of the bulbs of the right front foot. The ‘before’ image is on top, the ‘after’ image is on the bottom.

Both front hooves capsules had sheared heels and were abnormally toed-in, the front right hoof being the worse of the two.

Figure 5: The soles of the front hooves – ‘before’ pictures taken in March 2015 and ‘after’ ones taken in November 2015. The numbers show the percentage of the foot length which is ‘ahead’ of the widest part of the hoof. The fact that the numbers are larger in the ‘after’ images means that the widest part of the foot moved backwards.

The front right limb had a wind puff at the fetlock. Both front hooves had abnormally high heels causing Monte to stand too far behind its shoulders.

Figure 6: Lateral images of the front right hoof before (left) and after (right). The red arrow shows a ‘wind puff’ that disappeared in 6 weeks.

The before heel height was 1.5 in, whereas the after heel height was decreased to 0.92 in. Note that the heels were not lowered all at once.

The after picture was taking after trimming. Meaning this was the second time that Monte’s heels were reduced. The heel to bulb distance was also reduced after the second trimming. This is important because it brings the capsule in a better position for supporting the entire limb.

His hind hooves were underslung and displayed serious wall separation.

Distortions are also within the walls, such as compressed areas in the hoof wall. These are a bit more difficult to notice.

Figure 7: Rear soles before and after. The ‘before’ pictures were taken in March 2015. Both hooves had wall separation and white line disease.

Interestingly the wall separation was on the lateral (outside) wall of the

left hind while the opposite occurred on the right hind. The ‘after’ sole pictures were taken in November 2015.

Part of my approach with such cases is to allow the capsule to flex as intended, hence the use of polyurethane shoes.

The keratin has specific mechanical properties. Metal does not match these properties, whereas polyurethane does. It does not mean that metal shoes should be blamed for all hoof issues. Poor trimming practices and irresponsible physical demand on the horse are often at the root of hoof problems. The most important factor to recovery is trimming. When I trim, I orient the hoof capsule as best as I can to the bone axis. This is explained in greater details in my book “A Modern Look at the Hoof”. I do not believe in strict trimming or shoeing formulas. Every hoof is different.

The goal with good trimming is to maintain the hoof under the bony column. The proper trim of the hoof capsule provides good support to the limb. I hope to publish a follow-on article on this horse in a few months.