higher molecular weight products are more effective, while others minimize
the importance of size and suggest the activity of HA is mediated
pharmacologically rather than physically. More clinical studies are necessary
to prove efficacy of higher or lower molecular weights of hyaluronic acid.
Clinicians who use HA should bear in mind that post-injection flares may
occur. Flares may be associated with the purity and the source of the product.
Bacterial biofermentation as well as foreign proteins have been blamed for
these flares and increased attention is being paid to multi-step microfiltration
processes to purify HA products prior to clinical use.
Intra-articular injections of HA in human patients palliate pain and improve
articular mobility. Clinical benefits in horses are less well documented. Use in
joints with advanced disease often yield disappointing results compared to
joints with simple synovitis.
HA is available as formulations for both intravenous and intra-articular
administration. Experimental data from an animal model of OA indicated that
intravenous HA treatment did not improve the articular cartilage morphology,
but did improve lameness and reduced levels of the inflammatory mediator
PGE2 for up to 72 days post treatment.
Practitioners have recognized a beneficial effect of combination therapy of HA
and steroids to treat synovial inflammation for quite some time. Synergistic
effects have been reported in human patients but not in horses. Many
clinicians believe that the combination allows a smaller dose of corticosteroids
to be administered with the HA, and provides a longer clinical effect than
either injection alone, especially in high-motion joints.
•
Clinical usage:
• optimal results in horses with single joint problems without radiographic
signs of OA
• series of three to five injections at 7- to 14-day intervals, in combination
with a gradually increasing exercise regime until soundness ensues, or
until nor further improvement occurs following 2 consecutive injections.
Polysulphated Glycosaminoglycans
PSGAGs
are
principally
comprised
of
chondroitin
sulfate,
a
glycosaminoglycan found in the aggregating proteoglycan of cartilage. It is a
semisynthetic preparation from bovine trachea and is reported to have
chondroprotective and anti-inflammatory properties as well as the ability to
induce articular cartilage matrix synthesis and minimize matrix degradation.
The exact mechanism of action remains unclear. The drug most commonly is
administered intramuscularly but it is unlikely that concentrations injected
intramuscularly can translate to similarly elevated concentrations in the joint
fluid. PSGAGS have shown an ability to decrease lameness and to modify OA
15-‐18
February
2016
East
London
Convention
Centre,
East
London,
South
Africa
157