By Dr. Mariette van den Berg B. AppSc. (Hons), MSc., PhD (Equine Nutrition)
Photography: Dr. Mariette van den Berg

Vitamin and mineral supplements abound – products for joint health support, a shiny coat, hoof quality, and much, much more. And the dietary supplement industry continues to grow. Joint health support products make up the second largest part of the many supplements available.

Many ingredients have been marketed for joint health. Some of these ingredients have been shown to be efficacious alone and/or in combination in published equine research, and others have less evidence to back up their claimed benefits. Therefore, in this Part 3 we aim to shed some light on the important information when considering using joint supplements for horses.

Anatomy of the joint

To understand how joint supplementation may help you horse, it’s important to know a bit about the anatomy of the (equine) joint.
A joint is an articulation between two or more bones in the body and are broadly classified by the tissue which connects the bones. Horses have three types of joints – synovial joints, cartilaginous joints, and fibrous joints. Of the three different types of joints, the synovial joint is the most common type in the horse’s body.
Synovial joints are freely movable anatomic structures made up of the articular cartilage, the synovial fluid (joint fluid), and the soft tissue structures that hold the joint together (capsule and ligaments) – see figure 1. Examples of synovial joints are stifle, hock, knee, fetlock, etc. Synovial joints are complex organs in which all constituent tissues (articular cartilage, (subchondral) bone, and synovial membrane) interact with each other, both directly and via the synovial fluid, in health and disease.1 The articular cartilage and the synovial fluid are very important:
The articular cartilage is made up of chondrocytes (cartilage cells) that reside with a matrix. The matrix is made up of proteoglycans, collagen, and elastin. The proteoglycans are made up of a core strand of hyaluronic acid, a type of glycosaminoglycans (GAGs), with branches of other types of GAGs (including Chondroitin sulfate). Water sticks to the GAGs and gives the cartilage resistance to pressure.
The synovial fluid contains two main components. The first is the fluid part which is produced from filtrated blood plasma. The second component is hyaluronic acid. It is produced by cells of the synovial lining of the joint capsule. The joint fluid acts as a shock absorber, decreases friction, supplies oxygen and nutrients to the chondrocytes, and removes waste.
Inflammation develops when there is stress or wear and tear on these structures. The inflammatory factors (including inflammatory cytokines, matrix catabolic proteases, and neuropeptides) degrade the structures and quality of the cartilage and joint fluid. Normally, the joint is able to respond by producing new joint fluid and cartilage cells, but if this process is overwhelmed, then permanent damage can occur, thus producing an unhealthy and sometimes painful joint (see figure 1).
As horse owners, we want to enjoy riding our horses and keeping them healthy for many years to come. Therefore, we want to reduce this stress and inflammation in our horse’s joints and these have been the target for joint supplements. Joint supplements contain ingredients that are part of the make-up of either the articular cartilage or the synovial fluid. There are also supplements that act as anti-inflammatories. For more advanced diseas, there are prescription-only treatments available from your veterinarian... To read the complete article you need to be a subscriber

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