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
When arthritis changes are advanced as in this example,
joint nutraceuticals may slow progression, but very advanced loss of
cartilage and joint space carries a poor prognosis for return to working soundness.
HA excels in getting rapid control of inflammation. If you have a hot, acutely swollen joint go with
HA. In my experience. I’m not convinced it has a lot of value orally in joints that
do not have an obvious inflammatory component. I have seen horses do better when switched from a
glucosamine only or mixed glucosamine and chondroitin supplement to one that also includes
hyaluronic acid, MSM and some powerful anti-oxidents
Glucosamine, chondroitin and hyaluronic acid are absorbed orally; glucosamine and hyaluronic
acid intact, chondroitin primarily in disaccharide form.
Glucosamine is the precursor for hyaluronic acid and keratan in joints
Glucosamine, chondritin and hyaluronic acid all block inflammory enzymes and cytokines in
joints, relieving the suppressive effect inflammation has on GAG synthesis.
Hyaluronic acid provides the most effective and rapid relief from inflammation.
Glucosamine and chondroitin in combination works better than either one alone.
Other Disease Modifying Supplements
Avocado-Soy Unsaponifiables (ASU) is the most recent addition to this category. Hot off the presses
(still smoking actually) is this just published study:
Evaluation of avocado and soybean unsaponifiable extracts
for treatment of horses with experimentally induced
Kawcak CE, Frisbie DD, McIlwraith CW, Werpy NM, Park RD.
Kawcak CE, Frisbie DD, McIlwraith CW, Werpy NM, Park RD.
Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, College of
Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
OBJECTIVE: To evaluate the use of a combination of avocado and soybean unsaponifiable
(ASU) extracts for the treatment of experimentally induced osteoarthritis in horses. ANIMALS:
16 horses. PROCEDURES: Osteoarthritis was induced via osteochondral fragmentation in 1
middle carpal joint of each horse; the other joint underwent a sham operation. Horses were
randomly allocated to receive oral treatment with ASU extracts (1:2 [avocado-to-soybean] ratio
mixed in 6 mL of molasses; n = 8) or molasses (6 mL) alone (placebo treatment; 8) once daily
from days 0 to 70. Lameness, response to joint flexion, synovial effusion, gross and histologic
joint assessments, and serum and synovial fluid biochemical data were compared between
treatment groups to identify effects of treatment. RESULTS: Osteochondral fragmentation
induced significant increases in various variables indicative of joint pain and disease. Treatment
with ASU extracts did not have an effect on signs of pain or lameness; however, there was a
significant reduction in severity of articular cartilage erosion and synovial hemorrhage (assessed
grossly) and significant increase in articular cartilage glycosaminoglycan synthesis, compared
with placebo-treated horses. CONCLUSIONS AND CLINICAL RELEVANCE: Although
treatment with ASU extracts did not decrease clinical signs of pain in horses with experimentally
induced osteoarthritis, there did appear to be a disease-modifying effect of treatment, compared
with findings in placebo-treated horses. These objective data support the use of ASU extracts as
a disease-modifying treatment for management of osteoarthritis in horses.
Boswellia needs to be mentioned because it is so commonly used. An excellent review can be found
full text here:
Turmeric (curry) is receiving a lot of attention in human medicine the last few years. The active
components are curcuminoids (aka curcumin).
The parent herb, turmeric, contains about 2% curcumin.
In vivo studies on curcumin supplementation are promising, including one human rheumatoid arthritis
trial that found it was as effective as phenylbutazone when dosed at 1200 mg actual curcumin/day. That
would be a minimum of 4800 mg (4.8 grams) for a horse, or a whopping 240 grams (8.45 ounces) of
the parent herb, turmeric! Poor intestinal absorption and/or rapid hepatic first pass metabolism is the
reason for the high doses. Studies are underway to determine ways to improve bioavailability. For more
details on curcumin, see:
Many other herbs have been suggested for use in horses with joint problems.
To date they are some herbs that are researched to have promising effects.