Page 702 - Adams and Stashak's Lameness in Horses, 7th Edition

668 Chapter 5

Depo‐Medrol at a concentration of 40 mg/mL is most been used in human orthopedics (Orthokine®) since
frequently used at 80–100 mg/joint. Use of Depo‐Medrol 1998 for treatment of OA, rheumatoid arthritis, and spi-
VetBooks.ir this product has a high incidence of flare reactions. reviewed publications published in the literature regarding
nal disorders. There have been no case‐controlled or peer‐
at the 80 mg/mL concentration should be discouraged as
the efficacy of IRAP in DT joint OA in the horse. When
Triamcinolone can be used at 4–9 mg/joint depending
on how many joints are to be injected. Most clinicians using IRAP/IRAPII for the DIT or TMT joint, the manu-
do not exceed a total body dose of 18–20 mg because of facturer recommends using 1–2 mL/joint every 14 days
reported increased risk for laminitis, although this dose for three treatments. This treatment needs to be evaluated
limitation seems to be a source of debate. The frequency clinically and with controlled research. 53,96
of injection should not be more often than every 3–4 Alternatively, intra‐articular injections of PSGAG
months and in most instances twice a year is sufficient. (three injections given every 2 weeks) have also been
It is thought that corticosteroid injections can be used in competition and racehorses with DT joint pain.
repeated two or three times per year without promoting
progressive radiological change. There are no controlled Extracorporeal Shockwave Therapy (ESWT)
clinical trials assessing the relative efficacy of different
corticosteroids or the use of the combination of corti- The use of extracorporeal shockwave therapy (ESWT)
costeroids and hyaluronan, although some clinicians in horses with DT OA was first described in a series 74
believe that combination therapy provides a longer clin- predominately western performance horses (130 joints).
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ical effect. Hyaluronan alone is of questionable value. The horses had been treated medically and had either
If the PIT joint is involved, the control of synovitis is become refractory to IA treatment or the response had
indicated to prevent, or at least retard, development of reached an unacceptably short duration. Horses were
OA in the TC joint. Frequent injections of the TC (and treated under general anesthesia and received 2000
therefore the PIT joint) should be discouraged as this is pulses. Fifty‐nine of 74 horses (80%) showed improve-
a high range motion joint and can be at risk of develop- ment in lameness of at least 1 grade 90 days after treat-
ing progressive OA. Some clinicians suggest that hyalu- ment, but only 13 (18%) were sound. No radiographic
ronan prolongs the anti‐inflammatory effects of the differences were detectable between pre‐ and 90‐day
corticosteroid and can counteract the negative effects of posttreatment evaluations. The fact that ESWT stimu-
MPA; however there is no evidence to support this. lated no further ankylosis in the large series of horses
There is even conflicting evidence about whether HA with DT OA might cause one to more strongly consider
combination therapy with TA or betamethasone esters pain relief as a significant component of the mode of
does in fact prolong the chondroprotective effects of the action. An analgesic effect of ESWT was thought to be
corticosteroids. Lastly, disagreement also exists with the cause of improvement seen in these horses.
respect to whether HA should be used at all because of
the limited fluid volume that can be injected into the DT Bisphosphonates
joints. Chronic administration of intra‐articular corti-
costeroid should prompt regular radiographic evalua- Bisphosphonates are thought to be the most potent
tion of cuboidal tarsal bone density to detect the degree inhibitors of bone resorption clinically available to
of advancement of OA in these joints. human and veterinary medicine. Two bisphosphonates
A recent study evaluated the concentration of MPA that are now commercially available for use in the horse
or its ester methylprednisolone (MP) in the DIT joint are tiludronate (Tildren ) and clodronate (Osphos ). An
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after injection of MPA into the TMT joint. Injection of intravenous form of tiludronate (Tildren ) has been used
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80 mg of MPA into the TMT joint allowed diffusion into in horses at 0.1 mg/kg bwt/day for 10 days and is currently
the DIT joint. It was thought that the MPA and/or MP licensed for the treatment of navicular disease and bone
130
may have diffused either through the tarsal canal and spavin. The main action of tiludronate is the inhibition
space between the fused first and second tarsal bones of osteoclasts, which in turn inhibits bone resorption.
and the third tarsal bone or through the thin synovial Tiludronate slows down bone remodeling and is felt to
membrane. Regardless of the mode of diffusion, mole- restore a normal balance between bone resorption and
cules of MPA or MP were found to diffuse from the bone formation. Tiludronate has also been shown to
TMT joint into the DIT joint in a concentration that have anti‐inflammatory properties by decreasing the
was believed to be high enough to suppress inflamma- amount of nitric oxide and cytokines released from acti-
tion. The authors proposed that horses affected with OA vated macrophages, which promote the early inflamma-
of both the DIT and TMT joints that are treated by tion response. A recent clinical study showed that
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intra‐articular injection of MPA can be treated by instill- Tildren was effective in treating bone spavin in horses
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ing MPA into the TMT joint alone. However, it is ques- particularly when utilized in association with a con-
tionable whether this concentration is effective to trolled exercise program. Horses with periarticular oste-
manage DT pain. In addition, diffusion of MPA and MP ophytes and subchondral bone thickening were felt to
needs to be evaluated in horses with clinical disease of respond better. Little work has been performed to evalu-
these joints. ate clodronate (Osphos ) in the treatment of bone spavin
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Autologous conditioned serum (ACS) is thought to act in horses.
by blocking the receptor to the inflammatory cytokine
interleukin‐1 (IL‐1). 53,96 Arthrex Biosystems indepen-
dently patented the technique of IRAP enrichment of Farriery
serum and subsequent injection of this enriched serum Whatever protocol that is selected to treat horses
into joints as IRAP® and IRAPII®. The technique has with DT OA, it should be combined with corrective