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Why is HA (hyaluronan) important for joints?
Joints are classified into three different
categories: synar throses (non-movable),
amphiar throses (slightly moveable), and
diathroses (moveable).
The diarthrodal joints account for the greatest number in the body. Equine synovial joints
have many parts that all must work together
to provide an appropriate frictionless weightbearing surface. Simply put, articular cartilage
lines the bone of the joint. A synovial membrane surrounds the joint, this membrane provides synovial fluid that lubricates the joint.
Joint fluid comes from synoviocytes, which are
an integral component of the synovial membrane; these synoviocytes produce the proteins necessary for joint health. One of these
is hyaluronan (HA), a glycosaminoglycan
(GAG), which is a substance that attaches to
collagen and elastin to form cartilage.
HA not only helps keep the cartilage that
cushions joints strong and flexible, but also
helps increase supplies of joint-lubricating synovial fluid. Along with lubricin (another protein produced by synoviocytes) it is the main
source of lubrication in a diarthrodal joint.
HA is a major component of the synovial
fluid, as well as articular cartilage. HA in articular cartilage is synthesized locally by the
condrocytes. A molecule of HA acts as the center of molecules called aggrecans, that are
responsible for the hardiness and compressive stiffness of articular cartilage. Therefore,
without adequate amounts of HA, the joints
will become brittle and weaken. Molecules of
HA can vary greatly in size but are considered
relatively large. Because of this, HA plays an
important role in regulating what molecules
make up synovial fluid by preventing other
large molecules from entering the synovial
cavity. It helps bring nutrients to cells in the
joint and carry toxins away from those same
cells.
The amount of HA in each joint varies, with
smaller joints generally having a higher concentration than the larger ones. The concentrations of HA in equine joints affected with
radiographically apparent arthritis are generally
lower than healthy equine joints.
The exact mechanism by which endogenous
(made in the body) or exogenous (produced
outside the body) HA works is truly unknown.
However, multiple studies have shown all methods of administration; orally, intra-articularly,
and intravenously administered HA provide
benefits. These benefits include anti-inflammatory effects, pain relief, and increased joint
health. HA eventually breaks down and is absorbed in the body, so the effects are not permanent and continued treatment will be
necessary for continued beneficial effects.
Michael A. Spirito, D.V.M.
mspirito@hagyard.com
Dr. Michael A. Spirito attended veterinary school in
Torino, Italy, and graduated in
1980. While there, much of
his time was spent at local
racetracks examining lame
horses. He returned to the
U.S. to spend a year at the
New Jersey Equine Clinic and,
in 1982, began his work at
Hagyard Equine Medical Institute. His primary interest
is juvenile orthopedics, racehorse problems, sales, and
Pre-purchase work. Soft-tissue surger y involving the
broodmare and the young
horse is a large part of his
practice. He maintains a special interest and continues to
dedicate his career to lameness and confirmation issues.
With the highest level of HA (240mg/oz)
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Visit our online store for details!
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W ORKOUTS
TUESDAY
Horse
Al Khali, 5, r.
Awesome Act, 4, r.
Calibrachoa, 4, c.
California Flag, 7, g.
Capt. Candyman Can, 5, g.
Cost of Freedom, 8, g.
Custom for Carlos, 5, h.
Daisy Devine, 3, f.
Expansion, 6, h.
Gilded Gem, 5, m.
Harissa, 4, f.
Here Comes Ben, 5, h.
Jardin, 5, m.
Track
Churchill Downs
Churchill Downs
Churchill Downs
Santa Anita
Skylight Training Center
Hollywood
Churchill Downs
Churchill Downs
Churchill Downs
Churchill Downs
Belmont training track
Keeneland
Keeneland
Dist.
5f
5f
5f
3f
4f
4fAW
5f
5f
6f
6f
4f
5fAW
5fAW
Time
1:02.20b
1:02.40b
1:01.80b
:37.40h
:50.40b
:47.40h
1:03.00b
:59.60b
1:13.80b
1:15.80b
:50.23b
:59.60b
1:02.60b
Rank
14/25
16/25
10/25
11/14
1/2
2/16
19/25
1/25
3/9
6/9
33/49
1/21
12/21
Horse
Joe Vann, 3, c.
Midnight Interlude, 3, c.
Moryba (Brz), 5, h.
Musketier (Ger), 9, h.
Mythical Power, 5, h.
Not for Silver, 5, h.
Regally Ready, 4, g.
Riley Tucker, 6, h.
Santiva, 3, c.
Uncle Mo, 3, c.
Unrivaled Belle, 5, m.
Wilkinson, 3, c.
Wise Dan, 4, g.
Track
Dist.
Belmont training track 4f
Churchill Downs
6f
Payson Park
5f
Keeneland
4fAW
Churchill Downs
6f
Laurel
5f
Churchill Downs
4f
Churchill Downs
4f
Churchill Downs
4f
Churchill Downs
5f
Payson Park
5f
Churchill Downs
4f
Keeneland
6fAW
Time
:49.60b
1:13.60b
1:01.40b
:47.80b
1:13.60b
1:02.00b
:52.80b
:52.20b
:49.20b
1:01.80b
1:02.80b
:51.20b
1:12.40b
Rank
19/49
1/9
1/8
1/38
1/9
5/17
39/42
35/42
18/42
10/25
6/8
31/42
1/3
List of workouts is for all graded stakes winners at tracks and training centers in the United States and Canada, plus some selected horses.
AW—denotes all-weather surface Note: b-breezing, h-handily; Rank lists horse’s workout time compared with all others
who worked that distance at the track that day.
www.thoroughbredtimes.com
Thoroughbred Times TODAY April 27, 2011
6