Objective—To determine the outcome of horses
with basal fractures of the proximal sesamoid bone
from which a fracture fragment involving a portion of
the base of the bone was removed arthroscopically
and to determine whether fragment size was associated
Procedure—Dorsopalmar and axial-abaxial lengths of
the fracture fragment were measured on the dorsopalmar
and mediolateral radiographic views,
respectively, and percentage of the base of the
sesamoid bone involved was estimated. Fractures
were classified as grade 1 (≤ 25% of the base
involved) or grade 2 (> 25% but < 100% of the base
involved). Outcome was classified as successful if the
horse started at least 2 races or unsuccessful if the
horse started only 1 race or failed to return to racing.
Results—There were 24 racehorses and 2 nonracehorses.
Twelve (50%) of the racehorses returned to
racing and started at least 2 races. Eight of 14 horses
with grade-1 fractures and 4 of 10 horses with grade-
2 fractures had a successful outcome. Ten of 16 horses
without associated articular disease had successful
outcomes, compared with 2 of 8 horses with associated
articular disease. However, fragment size and
presence of associated articular disease were not significantly
associated with outcome.
Conclusions and Clinical Relevance—Horses with
basal fractures of the proximal sesamoid bone from
which a fracture fragment involving a portion of the
base of the bone is removed arthroscopically have a
fair prognosis for return to racing. (J Am Vet Med
Objective—To determine the effects of exercise at an early age on tissues in the metacarpophalangeal joints of horses.
Animals—Twelve 18-month-old horses.
Procedures—All horses were pasture reared, but 6 horses had additional exercise starting at 3 weeks of age until 18 months of age. At that time, computed tomography, articular cartilage metabolism evaluation, and histologic assessments of synovial membrane, articular cartilage, and subchondral bone were performed.
Results—Exercised horses had fewer gross lesions, less articular cartilage matrix staining in the dorsal aspect of the condyle, greater bone fraction in the dorsolateral aspect of the condyle, and higher bone formation rate, compared with nonexercised horses.
Conclusions and Clinical Relevance—Exercise at a young age may be protective to joints, although more research is needed to characterize changes in articular cartilage matrix. Results suggested that exercise can be safely imposed at an early age.
Objectives—To evaluate the effects of equine recombinant
interleukin-1α (rEqIL-1α) and recombinant interleukin-
1β (rEqIL-1β) on proteoglycan metabolism and
prostaglandin E2 (PGE2) synthesis by equine articular
chondrocytes in explant culture.
Sample Population—Near full-thickness articular
cartilage explants (approx 50 mg) harvested from
stifle joints of a 3-year-old and a 5-year-old horse.
Procedure—Expression constructs containing
cDNA sequences encoding EqIL-1α and EqIL-1β
were generated, prokaryotically expressed, and the
recombinant protein purified. Near full-thickness
articular cartilage explants (approx 50 mg) harvested
from stifle joints of a 3-year-old and a 5-year-old
horse were separately randomized to receive rEqIL-
1α or rEqIL-1β treatments (0 to 500 ng/ml).
Proteoglycan release was evaluated by 1,9-dimethylmethylene
blue spectrophotometric analysis of
explant media glycosaminoglycan (GAG) concentration
and release of 35S-sulfate-labeled GAG to explant
media. Proteoglycan synthesis was assessed by
quantification of 35S-sulfate incorporation into proteoglycan.
Explant media PGE2 concentrations were
evaluated using a PGE2-specific enzyme-linked
immunoassay. Data were collected at 48-hour intervals
and normalized by DNA content.
Results—Proteoglycan release was induced by rEqIL-
1α and rEqIL-1β at concentrations ≥ 0.1 ng/ml, with 38
to 76% and 88 to 98% of total GAG released by 4 and
6 days, respectively. Inhibition of proteoglycan synthesis
(42 to 64%) was observed at IL-1 concentrations
≥ 0.1 ng/ml at 2 and 4 days. Increased PGE2 concentrations
were observed at IL-1 concentrations ≥
0.1 ng/ml at 2 and 4 days.
Conclusions and Clinical Relevance—The rEqIL-1
induced potent concentration-dependent derangement
of equine chondrocyte metabolism in vitro .
These findings suggest this model may be suitable
for the in vitro study of the pathogenesis and treatment
of joint disease in horses. (Am J Vet Res 2002;
Objective—To evaluate the use of serum concentrations
of biochemical markers of bone metabolism
(osteocalcin [OC], bone-specific alkaline phosphatase
[BS-ALP], and deoxypyridinoline [DPYR]) to compare
healing in infected versus noninfected fractures and in
fractures with normal repair versus delayed (nonunion)
repair in rabbits.
Animals—32 female 9- to 10-month-old New Zealand
Procedure—A femoral fracture defect was made in
each rabbit. Rabbits were assigned to the following
groups: the bone morphogenetic-2 gene treatment
group with either noninfected nonunion or infected (ie,
inoculation of defects with Staphylococcus aureus)
nonunion fractures or the luciferase (control) gene
treatment group with either noninfected nonunion or
infected nonunion fractures. Serum samples were
obtained before surgery (time 0) and 4, 8, 12, and 16
weeks after surgery. Callus formation and lysis grades
were evaluated radiographically at 16 weeks.
Results—Serum OC and BS-ALP concentrations
decreased from time 0 at 4 weeks, peaked at 8
weeks, and then decreased. Serum DPYR concentration
peaked at 4 weeks and then decreased, independent
of gene treatment group or fracture infection
status. Compared with rabbits with noninfected fractures,
those with infected fractures had lower serum
OC and BS-ALP concentrations at 4 weeks, higher
serum OC concentrations at 16 weeks, and higher
serum DPYR concentrations at 4, 8, and 16 weeks.
Combined serum OC, BS-ALP, and DPYR concentrations
provided an accuracy of 96% for prediction of
fracture infection status at 4 weeks.
Conclusions and Clinical Relevance—Measurement
of multiple serum biochemical markers of bone
metabolism could be useful for clinical evaluation of
fracture healing and early diagnosis of osteomyelitis.
( J Am Vet Med Assoc 2003;64:727–735)
Objective—To evaluate effects of extracorporeal shock wave therapy (ESWT) and polysulfated glycosaminoglycan treatment (PSGAGT) on subchondral bone (SCB), serum biomarkers, and synovial fluid biomarkers in horses with induced osteoarthritis.
Animals—24 healthy 2- to 3-year-old horses.
Procedures—An osteochondral fragment was created on the distal aspect of the radial carpal bone in 1 middle carpal joint of each horse. Horses were randomly allocated to receive local application of ESWT (days 14 and 28; n = 8), PSGAGT (IM, q 4 d for 28 days; 8), or a sham ESWT probe (placebo; days 14 and 28; 8). Serum biomarkers were measured every 7 days, and synovial fluid biomarkers were measured every 14 days. Bone density was measured by use of computed tomography on days 0 and 70, and microdamage and bone formation variables were compared among groups at the end of the study (day 70).
Results—There was no significant effect of ESWT or PSGAGT on any bone variable. Serum osteocalcin concentration was significantly greater in horses that received ESWT, compared with placebo-treated horses, and serum concentration of the C-terminal telopeptide of type I collagen was significantly higher in horses that received ESWT, compared with placebo- and PSGAG-treated horses. Concentrations of the synovial fluid epitope CS846 were significantly higher in joints with osteoarthritis treated with ESWT
Conclusions and Clinical Relevance—Treatment of osteoarthritis with ESWT had no effect on SCB but did induce increases in serum biomarkers indicative of bone remodeling. Treatment of osteoarthritis with PSGAG had no effect on SCB or biomarkers.
Objective—To assess clinical, biochemical, and histologic effects of polysulfated glycosaminoglycan (PSGAG) or sodium hyaluronan administered intra-articularly in treatment of horses with experimentally induced osteoarthritis.
Procedures—Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses received hyaluronan (20 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight horses received PSGAG (250 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight control horses received 2 mL of saline (0.9% NaCl) solution and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Clinical, radiographic, synovial fluid analysis, gross, histologic, histochemical, and biochemical findings were evaluated.
Results—No adverse treatment-related events were detected. Induced osteoarthritis caused a substantial change in lameness, response to flexion, joint effusion, and radiographic findings, and of these, synovial fluid effusion was reduced with PSGAG, compared with control horses. No changes in clinical signs were seen with PSGAG or hyaluronan, compared with control horses. Histologically, the degree of synovial membrane vascularity and subintimal fibrosis was significantly reduced with PSGAG treatment, compared with controls. Histologically, significantly less fibrillation was seen with hyaluronan treatment, compared with controls.
Conclusions and Clinical Relevance—Results indicated that PSGAG and hyaluronan had beneficial disease-modifying effects and are viable therapeutic options for osteoarthritis in horses.
Objective—To assess the clinical, biochemical, and histologic effects of extracorporeal shock wave therapy (ESWT) in the treatment of horses with experimentally induced osteoarthritis (OA).
Animals—Twenty-four 2- to 3-year-old horses without evidence of lameness.
Procedures—OA was induced arthroscopically in 1 middle carpal joint of each horse. Fourteen days after induction of OA, horses were treated with a sham ESWT probe (placebo; n = 8), polysulfated glycosaminoglycan (PSGAG) administered IM every 4 days for 28 days as a positive control treatment (8), or ESWT administered on days 14 and 28 with a focused shock wave unit (8). Evaluations included clinical assessments of degree of lameness every 2 weeks and weekly synovial fluid analyses. Horses were euthanized 70 days after induction of OA, and gross pathologic and histologic examinations of cartilage and synovial membrane specimens were performed at necropsy. A generalized linear mixed model was used to compare outcomes among treatment groups.
Results—No adverse treatment-related events were detected in any horse. The degree of lameness in horses treated with ESWT improved significantly, compared with the degree of lameness in placebo- or PSGAG-treated horses. No disease-modifying effects were evident in results for synovial fluid, synovial membranes, or cartilage from the ESWT- or PSGAG-treated horses.
Conclusions and Clinical Relevance—Although a disease-modifying effect of ESWT was not detected, the significant clinical effect of ESWT suggested that this modality should be considered for treatment of horses with OA in combination with another modality that does affect the disease process.
Objective—To determine response of interleukin-1α
(IL-1α)-conditioned equine articular cartilage explants
to insulin-like growth factor-1 (IGF-1).
Sample Population—Cartilage from the trochlea and
condyles of the femur of a clinically normal 4-year-old
Procedure—Effects of IGF-1 (0 to 500 ng/ml) after
addition of IL-1α were evaluated by assessing matrix
responses, using a sulfated glycosaminoglycan (GAG)
assay, matrix 35SO4 GAG incorporation, and release of
GAG. Mitogenic response was assessed by 3H-thymidine
incorporation into DNA and fluorometric assay of
total DNA concentration.
Results—Human recombinant IL-1α (40 ng/ml)
increased the amount of labeled GAG released and
decreased labeled and total GAG remaining in
explants, and IL-1α decreased mitogenic response.
Addition of IGF-1 counteracted effects seen with IL-1α
alone. In general, IGF-1 decreased total and labeled
GAG released into the medium, compared with IL-1α-
treated explants (positive-control sample). Values for
these variables did not differ significantly from those
for negative-control explants. A significant increase in
total and newly synthesized GAG in the explants at
termination of the experiment was observed with
500 ng of IGF-1/ml. Labeled GAG remaining in
explants was greater with treatment at 50 ng of
IGF-1/ml, compared with treatment with IL-1α alone.
Concentrations of 200 ng of IGF-1/ml abolished
actions of IL-1α and restored DNA synthesis to values
similar to those of negative-control explants.
Conclusions and Clinical Relevance—IGF-1 at 500
ng/ml was best at overcoming detrimental effects
associated with IL-1α in in vitro explants. These beneficial
effects may be useful in horses with
osteoarthritis. (Am J Vet Res 2000;61:436–441)
Objective—To use microarray analysis to identify genes that are differentially expressed in horses with experimentally induced osteoarthritis.
Procedures—During arthroscopic surgery, a fragment was created in the distal aspect of the radiocarpal bone in 1 forelimb of each horse to induce osteoarthritis. At day 14 after osteoarthritis induction, horses began exercise on a treadmill. Blood and synovial fluid samples were collected before and after surgery. At day 70, horses were euthanized and tissues were harvested for RNA analysis. An equine-specific microarray was used to measure RNA expression in peripheral WBCs. These data were compared with mRNA expression (determined via PCR assay) in WBCs, cartilage, and synovium as well as 2 protein biomarkers of cartilage matrix turnover in serum and synovial fluid.
Results—A metalloproteinase domain-like protein decysin-1 (ADAMDEC1), glucose-regulated protein (GRP) 94, hematopoietic cell signal transducer (HCST), Unc-93 homolog A (hUNC-93A), and ribonucleotide reductase M2 polypeptide (RRM2) were significantly differentially regulated in WBCs of horses with osteoarthritis, compared with values prior to induction of osteoarthritis. There was correlation between the gene expression profile in WBCs, cartilage, and synovium and the cartilage turnover proteins. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in WBCs were correlated when measured via microarray analysis and PCR assay.
Conclusions and Clinical Relevance—Expression of ADAMDEC1, GRP94, HCST, hUNC-93A, and RRM2 was differentially regulated in peripheral WBCs obtained from horses with experimentally induced osteoarthritis. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in peripheral WBCs has the potential for use as a diagnostic aid for osteoarthritis in horses.
Objective—To compare the mesenchymal stem cell (MSC) yield and chondrogenic and osteogenic differentiation from 5- and 50-mL bone marrow aspirates from horses.
Animals—Six 2- to 5-year-old mixed-breed horses.
Procedures—2 sequential 5-mL aspirates were drawn from 1 ilium or sternebra. A single 50-mL aspirate was drawn from the contralateral ilium, and 2 sequential 50-mL aspirates were drawn from a second sternebra. The MSC yield was determined through the culture expansion process. Chondrogenesis and osteogenesis were evaluated by means of conventional laboratory methods.
Results—The second of the 2 sequential 50-mL sternal aspirates yielded few to no MSCs. Independent of location, the highest density of MSCs was in the first of the 2 sequential 5-mL fractions, although with subsequent culture expansion, the overall yield was not significantly different between the first 5-mL and first 50-mL fractions. Independent of location, chondrogenesis and osteogenesis were not significantly different among fractions. Independent of fraction, the overall cell yield and chondrogenesis from the ilium were significantly higher than that from the sternum.
Conclusions and Clinical Relevance—This study failed to detect an additional benefit of 50-mL aspirates over 5-mL aspirates for culture-expanding MSCs for equine clinical applications. Chondrogenesis was highest for MSCs from ilial aspirates, although it is not known whether chondrogenesis is indicative of activation of other proposed pathways by which MSCs heal tissues.