The researchers, Magdalena Senderska-Ponowska, Paulina Zelensky, Agnieszka Oak, and Mateusz Stefania are affiliates of Wrocaw University of Environmental and Life Sciences, Wrocaw, Poland. The aim of their study was to investigate the influence of metal horseshoes on heel contraction and to evaluate other risk factors (housing, age, breed, and sex) for this condition.
Metal horseshoes are often blamed for causing heel contraction, especially by natural hoof care practitioners, but no scientific comparison has to date been made focusing on shod and barefoot horses. A contracted heel is a common issue in domestic horses observed by farriers, veterinarians and breeders.
Diagram showing parts of hoof anatomy that work together to perform a unified function A contracted heel accompanies a small frog, which is more prone to bacterial and fungal infection.
A number of earlier studies reported that the traditional horseshoe restricts the heels' movement. Linear mixed-effects models were performed for the width:length ratio where the fixed effects were: age, sex, breed, pasture/paddock time, shoeing and its duration and limb.
A new study evaluated the influence of metal shoeing and other risk factors such as age, access to paddock and breed, on heel contraction in horses. The data obtained during the study show that the most important factors for hoof contraction were attributes of the individual horse.
This may mean that hoof contraction may be affected by features, which were not measured, for instance, genetics, weight, the environment in previous yard, or another characteristic of hoof morphology, such as the toe length or Palmer angle, the latter of which has been previously implicated, whereby a high Palmer angle is correlated with a narrow frog. The statistical analysis showed a positive relationship between shoeing and heel contraction, when determining only the effect of this factor.
This reflects previous anecdotal reports which stress that shoeing is a large risk factor for hoof distortions. Because of significant difference in incidence of contraction between yards, researchers determined that further investigation of environmental factors causing hoof distortion need to be studied.
No, thanks: Lions fire Matt Patricia, GM Bob Quinn They're applied by a farrier (the person that trims the horses hooves) and he nails them into the hoof.
Source(s): It was not until the onset of humans, who put the metal shoes on the horse hooves in aim to provide a safer “pad” on their horses hooves. Here are photos from wild horses that lived and died on dry, rocky, mountainous terrain.
“Mustang roll” refers to the rounded bevel around the bottom of their hoof wall.) Because the extremely healthy “white line” places the coffin (pedal) bone high inside the hoof capsule.
Most of our horses don't travel enough daily miles on hard ground, to have a totally healthy, tight white line. The white line is weakened and stretchy, therefore the wall and coronet migrate upward toward the pastern.
The hoof is a flexible structure which responds directly to the mechanical forces upon it, from the leg above and from the ground beneath. Then you have to think about what made it do this, and use today's trim to encourage the hoof to return towards its ideal shape.
Surrounding the bone is a thin layer of tissue called the cerium which has an extremely dense blood supply. All tissue-building, maintenance, and healing in the foot depend on the constant supply of nutrients brought to the cerium by the bloodstream.
On the outer / upper surface of the bone, the cerium builds a set of soft, fine “leaves” (patellae) which match a set of hard “leaves” (laminae) on the inside surface of the hoof wall. The two sets of “leaves” interlock like a sort of living Velcro, holding the wall and bone together.
The entire hoof wall, including the heels, grows forward at this slope. The hoof is a slanted cone shape, narrower at the top and wider at the bottom.
The hoof wall grows down the outside surface of the coffin bone, strongly attached by the laminae. It takes almost a year for the hoof wall to grow out completely at the toe, where it's longest.
The sharp, curved bottom edge of the coffin bone makes an arc (like a new moon). For correct alignment of the leg bones, this curved edge should sit nearly level on the ground.
What you see on an x-ray is not the bottom edge (which is too thin to show up well) but a cross-section through the body of the bone, which is concave so that it slopes upward. Instead, we can determine ground-parallel by using the sole (which matches the bottom of the coffin bone) as a guide to trimming the hoof.
In a healthy, well-trimmed foot that has never been shod, the frog is a wide, plump structure similar to the biggest pad of a dog's or cat's paw. Its health is maintained by the fact that it is in contact with the ground between the heel buttresses, and receives concussion at every step.
The frog should share the horse's weight with the sole, bars, heels, and water line (the white inner layer of hoof wall). Weight carried by the outer wall (as in a shod horse) is called “peripheral loading” and over time will damage the laminar tissue (white line) that holds the wall tightly onto the coffin (pedal) bone.
The frogs of shod horses are held 1/2 inch (1 cm) above the ground by the thickness of the horseshoe. They do not receive the concussion that they require, they become narrow and unhealthy, and they are often infected with yeasts (“fungus”) and bacteria (“thrush”).
Generally it is necessary to treat for infection (see More Topics page) so that the frog is not painful and the horse is willing to put weight on it. Often it is necessary to leave the heels 1/8 to 3/8 inch (3 to 10 mm) long to protect the diseased frog (and the weakened digital cushion above it) for several months while they become stronger.
The sole protects the coffin (pedal) bone from damage by rocks and hard ground. It is made by a spongy, blood-filled layer of tissue called the sole cerium on the bottom of the coffin bone.
The outer surface of the sole becomes hardened like a callus, especially around the toe under the sharp edge of the coffin bone. The horse's foot needs the full thickness of sole, across the entire bottom of the coffin bone, for protection.
If we trim the sole, the horse loses both some thickness and the hard, calloused surface. Because the sole is an even thickness over the entire bottom of the coffin bone, we can use it as an accurate landmark for trimming the wall.
When the wall is trimmed level with the sole -- the water line being no more than 1/16 inch (1 or 2 mm) longer than the nearby sole -- this puts the coffin bone in its correct position in relation to the ground (ground parallel). The drawings below of a short- and long-heeled shape (not accurate in details) show what happens to the coffin bone when the heels are long.
Click here to go to an excellent article in Professional Farrier Magazine, that explains the problems with the “box foot trim.” You can see rough calcifications on the Palmer processes (back corners) and some side bone developing (swelling above the heel).
The entire hoof wall grows from the coronet at the same slope as the coffin bone. No part of the hoof grows vertical (unless it is trimmed “box foot” style with a long heel and short toe).
Pink arrow shows a slight groove in the tubules (“hair” material that the wall is made of) which has the same slope as my lines. The shoe prevented the hoof from getting wider as it grew; instead it curled under, making a long cylinder shape.
If you force it with over-eager trimming, it's easy to cause white line separation from the contracted coffin bone. The heels need to be shortened to the edge of the sole, after scraping out a lot of chalky material in the seat of corn.
This horse will need many months of long walks on medium-firm ground (not sand, not soft arena, not pavement) to encourage re-shaping of the hooves. Front hoof (left and center) of a horse that was raised in Florida, where the ground is soft and sandy.
I suspect that, as a foal, he spent a lot of time standing in soft bedding. The hoof wall is what we call “inside the vertical”-- it is narrower at the bottom than at the top.
This shape cannot expand during weight bearing; thus it does not provide much circulation in the hoof and grows poorly. On the right, a normal hoof showing the cone shape which spreads on weight bearing, providing circulation inside the foot.
A flare is an outward curve at the bottom of the hoof wall, like the bell of a trumpet. The hoof wall should be a straight line from the hairline to the ground, all the way around the foot. These feet are flared because they are overdue for a trim.
More frequent trimming will get rid of these flares quickly; note the upper part of both feet has a strong white line connection. This fellow needs lots of lateral work (such as Pirelli “sideways game”) to strengthen and widen his chest.
If these landmarks (sole view and tubules) don't agree, then the coffin bone may have dropped on one side (stretched white line), or possibly eroded to a crooked shape -- one of the coffin bones in my collection slants about 5 degrees from level. Generally, vertebrae get out-of-line due to consistently uneven posture from unbalanced feet.