Horses’ well-being and survival depend on his capability of out-running natural predators, making the health of limbs extremely important.
Horse’s legs are evolved to carry a relatively heavy load on a relatively tiny and fragile limbs,
therefore we must stress the importance of limb health in the general well-being of the animal – when certain activities are performed, the limbs can get overloaded, resulting in injuries.
Horse front leg anatomy
Horse front legs
They are not attached by joints, but rather to a sling of muscles and ligaments that support the weight of the horse and rider. The shoulder blade, or scapula, is connected to the spine by muscle and ligaments and allows freedom of movement and absorption of a concussion.
is the upper-end form point of the shoulder and connects the shoulder blade to the forelimbs. The upper part of the foreleg consists of the ulna, a short bone that forms the point of the elbow, and the radius, which is a long bone that stretches to the knee joint.
Knee joint (or carpus)
is composed of the carpal bones and allows movement in the foreleg. The cannon bone is a weight-bearing bone in the lower leg and stretches from the knee joint to the fetlock joint. On either side of the cannon bone are the splints that help support the carpus bones of the knee.
Behind the fetlock joint, there are two bones known as the sesamoids. These bones provide a groove to hold the tendons of the leg, which act as a pulley system for movement of the lower leg.
The pastern bones occur above and below the pastern joint with the long pastern on top, between the fetlock and the joint, and the short pastern below the joint connecting to the coffin joint.
The pedal bone is a hoof-shaped structure in the foot that serves for the attachment of tendons and ligaments from the muscles in the forearm. The pedal bone, also known as the coffin bone or P3, is the main bone in the foot.
The navicular bone is a small bone located behind the pedal bone. The navicular bone functions as a pully for the deep flexor tendon that wraps around the navicular and is attached to the pedal bone.
Horse rear leg anatomy
Horse rear legs
The horse leg anatomy in the rear includes the bones of the pelvis (the ilium, ischium and pubic bones), femur, tibia, fibula, metatarsus and the phalanxes. It also includes the joints of the hip, stifle, hock, fetlock, pastern, and coffin.
The top part of the hind limbs consists of three fused bones, called the ileum, ischium, and pubis. The ischium forms the point of the buttock. They are joined to the spine through the sacroileac joints and allow transfer of propulsion to the hind legs.
Pelvis (pelvic girdle)
The pelvis or pelvic girdle serves to protect the inner organs, including the uterus. The femur, which is a large bone, connects with the pelvis at the hip joint and with the hind leg at the stifle joint. The tibia forms the upper part of the hind limb from the stifle to the hock. The fibula is a smaller bone that extends half the length of the tibia and sits parallel to it.
The patella, or kneecap, is the bone in the stifle joint above the fibula and tibia. The hock joint allows movement of the hind leg and consists of the tarsus bones, the tuber, and the calcaneus at the back, which forms the point of the hock. Below the hock joint are the hind cannon with splint bones, the long and short pastern, the coffin joint and bone, the sesamoid bones, and the pedal and navicular bones similar to those in the front limb.
Tendons are bands of dense connective tissue tying muscle to bone or cartilage. These structures are designed to passively transfer load across joints or to provide movement. The horse’s digital flexor tendons have evolved to store energy, absorb shock, and support weight-bearing joints.
A ligament is a band of tough connective tissue joining two bones or cartilages. Suspensory ligaments (SL) originate from the back of the fore and hind cannon bones. The SL’s main function is to prevent the fetlock joint from overextending. Researchers have shown that appropriate training in racehorses can improve the SL’s strength.
Deep digital flexor tendon (DDFT)
The deep digital flexor tendon (DDFT) arises from three locations in the upper forelimb: the humerus, radius, and ulna. It then courses down the carpal canal (the depression running down the back of the knee) and crosses over the navicular bone before inserting at the back of the coffin bone, lying deep beneath the SDFT and just over the suspensory ligament.
In the hind limb, the DDFT originates from two areas of the tibia and also inserts on the coffin bone. This tendon plays a role in the knee and forefoot flexion, forelimb elbow joint extension, and hock and hindfoot flexion and extension.
Horse Leg Injuries
Considering the fact that horse typically weighs 450 kilograms and more and all of that load (plus rider or additional load) is carried by four relatively small legs, the number of different types of limb injuries that can occur is considerable.
These injuries can be categorized as:
Tendon and ligament injuries, joint injuries and soft-tissue injuries around the joint, joint capsule, cartilage, and bone.
One of the most common types of horse tendon/ligament injuries is Superficial Digital Flexor Tendon (SDFT) injury – report.
In one study of British racehorses and National Hunt horses, SDFT injuries accounted for up to 90% of tendon/ligament injuries.
Deep Digital Flexor Tendon injury, Tendonitis, and Suspensory Desmitis are also very common horse joint problems.
How to Treat Horse Leg Injuries?
One of the biggest fears of horse owners is a leg injury that ends the horse’s career or sometimes threatens his life.
However, while some injuries might be too severe to allow for a full recovery, today it is possible to rehabilitate many of the more common leg injuries.
Many rehabilitated horses live long, comfortable lives, and a significant number are able to return to the same level of work.
Once you receive a diagnosis on horse leg injuries, it is important to work with your vet to design the appropriate rehabilitation program for your horse. Many rehabilitation programs progress from stall rest to hand walking, then a gradual return to riding and regular work, but timelines vary greatly based on the extent of the injury, so it is important to work closely with your vet.
Depending on your horse and his particular leg injury, your vet may also recommend cold therapy (such as icing or cold hosing), support bandages (like quilts and stable bandages), or Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) such as phenylbutazone (bute), Banamine®, Equioxx® Oral Paste or Surpass® Topical Cream to relieve pain and reduce inflammation.
Newer therapies such as IRAP (interleukin-1 receptor antagonist protein), stem cells and ESWT (extracorporeal shock wave therapy) are also beneficial.
For instance, researchers have shown that National Hunt
racehorses treated with stem cell therapy had an 80% return-to-performance rate as compared to the typical 30% with conventional techniques.
Medrego EquiCell stem cell therapy for horses has up to 90% high success rate, and the first results can be seen already after the first two weeks.
With a better understanding of the horse leg anatomy, most common injuries and how they occur, and what risk factors to look for and avoid in horse’s daily routine to minimize the occurrence of these problems, you’ll be more aware of what is happening to your horse’s limbs and what’s the most effective and least invasive treatment possible.
If your horse does experience a joint injury, please work with your vet to identify the cause promptly.
Don’t hesitate for a moment to provide appropriate diagnostic and treatment to resolve the problem as soon as possible – this will not only make the recovery far more speedy and successful but will significantly reduce the risk of repeated injury as well, improving the well-being and quality of life of your four-legged friend. There is also some expert advice you could use on horse joint injuries.