Understanding Equine Joint Structure and Function

January 13, 2015
By Debra M. Eldredge, DVM

When the term “soundness” is used for horses, it almost always means orthopedic soundness. Respiratory soundness is important too, but most people think of legs and joints first. Without healthy joints, many horses are sidelined for pasture retirement or euthanized.

What are Joints?

What is a joint, exactly, and what keeps it healthy? Joints are where two or more bones come together to absorb the shock of motion and provide movement. Horses have three different types of joints:

  • Synovial Joints: Synovial joints are the most common in the horse’s body. They help with movement and come in different shapes, such as the ball and socket of the hip joint or the hinge joint of the elbow. The exact shape of the joint determines how the joint moves; it may flex and extend or twist to a certain extent. The joint shape limits movement, as well as the tendons and ligaments involved with that joint.
  • Fibrous Joints: Fibrous joints are less common; these joints do not allow for movement. An example of fibrous joints would be those between the bones making up your horse’s skull.
  • Cartilaginous Joints: This category includes joints connected by cartilage, such as those between the vertebrae of your horse’s backbone. They allow for limited movement.
  • Tendons and Ligaments: Tendons are tough connective tissue that connects muscles to bones. Ligaments are also tough connective tissue, but they connect bone to bone. Tendons are more “elastic” and give a little, while ligaments are more rigid. Tendons also have more blood supply to help heal injuries.

Requirements for Healthy Joints

There are certain important anatomical requirements for health in all joints. You never want “bone on bone” in a joint because the bones will grate on each other. Fibrous joints are the exception; they are essentially fused together and don’t move.

For a healthy joint with a lot of motion, you need a cartilage cushion between the bones and some joint fluid—sometimes called synovial fluid—to help lubricate the joint action. A fibrous capsule around the “action” area of the joint stabilizes the joint. This capsule includes the synovial membrane, which produces the fluid to lubricate the joint. You also need stability, so the tendons and ligaments around a joint must be healthy and intact.

Causes of Injured Joints When Training and Competing

With so many different types of tissues involved, plus movement and wear and tear from concussive shock, it is no surprise that joints can be easily injured. Here are some common causes of injury:

  • Tendon and Ligament Wear
  • Wear and Tear
  • Trauma
  • Conformation

How to Keep Joints Healthy

Obviously, it pays to keep joints healthy if at all possible. Here are some tips on how to do so:

  • Choose your horse wisely. Look at conformation and movement. Make sure that the physique of the horse you are looking at fits with the riding and performance goals you have in mind.
  • Keep your horse fit and trim; extra weight means extra joint stress.
  • Stay on top of your horse’s hoof care and shoeing needs. A good farrier can help to compensate for some minor conformational faults.
  • Consider feeding a joint supplement, such as Joint Combo™ Hoof & Coat or Reach® Joint supplement, to be sure that your horse has the support he needs for healthy joints.
  • Perform a post-ride or daily “leg check;” you may detect an “ouchy” spot or feel increased heat around a joint. Always respond immediately. Cold hosing can help to reduce inflammation for minor injuries due to training or strenuous exercise, and stall rest may be required.

Don’t hesitate to consult your veterinarian if something looks out of the ordinary. Without sound joints, your horse’s performance career options are limited.

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