Equine Arthritis-Osteoarthritis-Joint Supplements
To make an intelligent decision about what, when and why to supplement to help a joint problem, you
first have to understand the parts of a joint and what can go wrong with them. The outermost layer of a
joint is the joint capsule (labelled articular capsule in the diagram above. Articulation is another word
for joint.) The next layer in is the synovial membrane or synovium. The synovium is a double layered
membrane. The layer facing the inside of the joint is very thin and secretes the joint fluid (aka synovial
fluid). The layer between the joint capsule and the inner layer varies from soft and fatty to very dense,
probably depending on how hard the joint is worked. (The digital cushion in the foot is like this too;
very soft at birth, toughening up over the first year or two of life as it gets worked.)
The synovial membrane coats all inner surfaces of the joint except where there is joint cartilage. Joint
cartilage is a specialized type of cartilage that coats the ends of the bone inside a joint. The specialized
cartilage in joints is called hyaline cartilage. Joints are the only area of the body where hyaline cartilage
is exposed. In all other areas that have cartilage (like the tip of the nose, the ear or the vocal cords), it is
covered by several other layers of tissue.
Cartilage has no blood or nerve supply. The cells get their nutrition from the joint fluid. The hyaline
cartilage has sponge-like characteristics. When bearing weight, the cartilage compresses and fluid is
forced out. When weight is taken off the joint, fresh fluid is restored to the cartilage. This is why
exercise is important to healthy cartilage.
Cartilage gets its sponge-like characteristics from the composition of the cartilage matrix. The matrix of cartilage is composed of water, type II collagen and the glycosaminoglycans which are chondroitin sulfate, hyaluronic acid and keratan sulfate.
Glucosamine is the starting point for many glycosaminoglycans.
Several factors will determine if a horse is likely to have a favorable response to glucosamine,
chondroitin and/or HA. Those factors are summarized in the chart below.
Is Your Horse a Good Candidate for a Joint Nutraceutical?
Joint effusions (increased joint fluid)
Minimal bony changes (osteophytes)
Favorable response to hyaluronic acid or
PSGAG (Adequan) injections
Incomplete or Poor Response
Decreased or uneven joint space on X-ray
Advanced bone changes
Damage to stabilizing ligaments (e.g. Collateral
ligaments) or soft tissue structures within the joint
(e.g. Meniscus or collateral ligaments in the stifle)
Unresolved balance or shoeing issues
Infectious problems (e.g. Lyme)ncomplete or Poor Response