Objective: To use microarray analysis to identify genes that are differentially expressed in horses with experimentally induced osteoarthritis. Animals: 24 horses. 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 determine the optimal method for use of the Canine Brief Pain Inventory (CBPI) to quantitate responses of dogs with osteoarthritis to treatment with carprofen or placebo. Animals—150 dogs with osteoarthritis. Procedures—Data were analyzed from 2 studies with identical protocols in which owner-completed CBPIs were used. Treatment for each dog was classified as a success or failure by comparing the pain severity score (PSS) and pain interference score (PIS) on day 0 (baseline) with those on day 14. Treatment success or failure was defined on the basis of various combinations of reduction in the 2 scores when inclusion criteria were set as a PSS and PIS ≥ 1, 2, or 3 at baseline. Statistical analyses were performed to select the definition of treatment success that had the greatest statistical power to detect differences between carprofen and placebo treatments. Results—Defining treatment success as a reduction of ≥ 1 in PSS and ≥ 2 in PIS in each dog had consistently robust power. Power was 62.8% in the population that included only dogs with baseline scores ≥ 2 and 64.7% in the population that included only dogs with baseline scores ≥ 3. Conclusions and Clinical Relevance—The CBPI had robust statistical power to evaluate the treatment effect of carprofen in dogs with osteoarthritis when protocol success criteria were predefined as a reduction ≥ 1 in PIS and ≥ 2 in PSS. Results indicated the CBPI can be used as an outcome measure in clinical trials to evaluate new pain treatments when it is desirable to evaluate success in individual dogs rather than overall mean or median scores in a test population.

Objective-To determine whether oxidative stress could be induced in canine chondrocytes in vitro. Sample-Chondrocytes obtained from healthy adult mixed-breed dogs. Procedures-Harvested chondrocytes were maintained at 37°C with 5% CO2 for 24 hours. To assess induction of oxidative stress, 2 stimuli were used: hydrogen peroxide and a combination of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). To determine the effect of hydrogen peroxide, a set of chondrocyte-seeded plates was incubated with control medium alone or hydrogen peroxide (100, 200, or 300μM) for 24 hours. For inhibition of oxidative stress, cells were incubated for 24 hours with N-acetylcysteine (NAC; 10mM) before exposure to hydrogen peroxide. Another set of chondrocyte-seeded plates was incubated with control medium alone or with IL-1β (10 ng/mL) and TNF-α (1 ng/mL) for 24 hours. Supernatants were obtained for measurement of prostaglandin E2 production, and cell lysates were used for measurement of superoxide dismutase (SOD) activity and reduced-glutathione (GSH) concentration. Results-Chondrocytes responded to the oxidative stressor hydrogen peroxide with a decrease in SOD activity and GSH concentration. Exposure to the antioxidant NAC caused an increase in SOD activity in hydrogen peroxide-stressed chondrocytes to a degree comparable with that in chondrocytes not exposed to hydrogen peroxide. Similarly, NAC exposure induced significant increases in GSH concentration. Activation with IL-1β and TNF-α also led to a decrease in SOD activity and increase in prostaglandin E2 production. Conclusions and Clinical Relevance-Canine chondrocytes responded to the oxidative stress caused by exposure to hydrogen peroxide and cytokines. Exposure to oxidative stress inducers could result in perturbation of chondrocyte and cartilage homeostasis and could contribute to the pathophysiology of osteoarthritis. Use of antioxidants, on the other hand, may be helpful in the treatment of arthritic dogs.

Objective: To identify proteins with differential expression between healthy dogs and dogs with stifle joint osteoarthritis secondary to cranial cruciate ligament (CCL) disease. Sample: Serum and synovial fluid samples obtained from dogs with stifle joint osteoarthritis before (n = 10) and after (8) surgery and control dogs without osteoarthritis (9) and archived synovial membrane and articular cartilage samples obtained from dogs with stifle joint osteoarthritis (5) and dogs without arthritis (5). Procedures: Serum and synovial fluid samples were analyzed via liquid chromatography–tandem mass spectrometry; results were compared against a nonredundant protein database. Expression of complement component 3 in archived tissue samples was determined via immunohistochemical methods. Results: No proteins had significantly different expression between serum samples of control dogs versus those of dogs with stifle joint osteoarthritis. Eleven proteins (complement component 3 precursor, complement factor I precursor, apolipoprotein B-100 precursor, serum paraoxonase and arylesterase 1, zinc-alpha-2-glycoprotein precursor, serum amyloid A, transthyretin precursor, retinol-binding protein 4 precursor, alpha-2-macroglobulin precursor, angiotensinogen precursor, and fibronectin 1 isoform 1 preproprotein) had significantly different expression (> 2.0-fold) between synovial fluid samples obtained before surgery from dogs with stifle joint osteoarthritis versus those obtained from control dogs. Complement component 3 was strongly expressed in all (5/5) synovial membrane samples of dogs with stifle joint osteoarthritis and weakly expressed in 3 of 5 synovial membrane samples of dogs without stifle joint arthritis. Conclusions and Clinical Relevance: Findings suggested that the complement system and proteins involved in lipid and cholesterol metabolism may have a role in stifle joint osteoarthritis, CCL disease, or both.

Objective-To evaluate the use of CT and MRI for guidance of osteochondral sample collection for histologic detection of early osteoarthritic lesions in centrodistal (distal intertarsal) joints of horses. Sample -Right tarsal joints from the cadavers of 24 Icelandic horses aged 29 to 31 months. Procedures-CT and MRI were used to evaluate the extent of suspected osteoarthritic changes in centrodistal joints, which were graded with a semiquantitative system. The anatomic regions with the highest grade of change were identified, and osteochondral samples were obtained from these regions. Samples were also obtained from the same centrodistal joints at predetermined sites. Histologic examination of all samples was performed, with samples classified as negative or positive for osteoarthritis, and results were compared between sample collection methods. Results-Histologic examination revealed osteoarthritic lesions in 29% (7/24) of centrodistal joints with the predetermined method and in 63% (15/24) with the image-guided method. Significant associations were identified between histologic osteoarthritis detection and the summed image-guided sample collection site image grades, central osteophytes, articular cartilage thickness abnormalities, grade 2 articular mineralization front defects, and grade 2 marginal osteophytes. Conclusions and Clinical Relevance-CT and MRI aided the detection of focal changes suggestive of early-stage osteoarthritis in the centrodistal joints of equine cadavers and may be useful for detection of similar disease in live horses. The first morphological changes of centrodistal joint osteoarthritis were suspected to be in the articular cartilage and the articular mineralization front regions.

Objective: To assess differences in sagittal plane joint kinematics and ground reaction forces between lean and obese adult dogs of similar sizes at 2 trotting velocities. Animals: 16 adult dogs. Procedures: Dogs with body condition score (BCS) of 8 or 9 (obese dogs; n = 8) and dogs with BCS of 4 or 5 (lean dogs; 8) on a 9-point scale were evaluated. Sagittal plane joint kinematic and ground reaction force data were obtained from dogs trotting at 1.8 and 2.5 m/s with a 3-D motion capture system, a force platform, and 12 infrared markers placed on bony landmarks. Results: Mean stride lengths for forelimbs and hind limbs at both velocities were shorter in obese than in lean dogs. Stance phase range of motion (ROM) was greater in obese dogs than in lean dogs for shoulder (28.2° vs 20.6°), elbow (23.6° vs 16.4°), hip (27.2° vs 22.9°), and tarsal (38.9° vs 27.9°) joints at both velocities. Swing phase ROM was greater in obese dogs than in lean dogs for elbow (61.2° vs 53.7°) and hip (34.4° vs 29.8°) joints. Increased velocity was associated with increased stance ROM in elbow joints and increased stance and swing ROM in hip joints of obese dogs. Obese dogs exerted greater peak vertical and horizontal ground reaction forces than did lean dogs. Body mass and peak vertical ground reaction force were significantly correlated. Conclusions and Clinical Relevance: Greater ROM detected during the stance phase and greater ground reaction forces in the gait of obese dogs, compared with lean dogs, may cause greater compressive forces within joints and could influence the development of osteoarthritis.

There is evidence that vitamin E (VE) has anti-inflammatory and analgesic properties in human osteoarthritis (OA). This double-blinded and randomized pilot study used a broad spectrum of clinical and laboratory parameters to investigate whether such beneficial effects could be detected in a canine experimental OA model. Dogs were divided into 2 groups: control (n = 8), which received a placebo, and test group (n = 7), which received 400 IU/animal per day of VE for 55 d, starting the day after transection of the cranial cruciate ligament. Lameness and pain were assessed using a visual analogue scale (VAS), numerical rating scale (NRS), and electrodermal activity (EDA) at day 0, day 28, and day 55. Cartilage and synovial inflammation lesions were assessed. One-side comparison was conducted at an alpha-threshold of 10%. At day 56, dogs were euthanized and concentrations of prostaglandin E2 (PGE2), nitrogen oxides (NOx), and interleukin-1 beta (IL-1β) were measured in synovial fluid. Concentrations of NOx and PGE2 in synovial fluid were lower in the test group (P < 0.0001 and P = 0.03, respectively). Values of VAS, NRS, and EDA showed a consistent trend to be lower in the test group than in the control, while statistical significance was reached for VAS at day 55 and for EDA at day 28 (adjusted P = 0.07 in both cases). Histological analyses of cartilage showed a significant reduction in the scores of lesions in the test group. This is the first time that a study in dogs with OA using a supplement with a high dose of vitamin E showed a reduction in inflammation joint markers and histological expression, as well as a trend to improving signs of pain.

Objective-To evaluate the effect of underwater treadmill exercise on static postural sway in horses with experimentally induced carpal joint osteoarthritis under various stance conditions. Animals-16 horses. Procedures-On day 0, osteoarthritis was induced arthroscopically in 1 randomly selected middle carpal joint of each horse. Beginning on day 15, horses were assigned to either underwater or overground (without water) treadmill exercise at the same speed, frequency, and duration. Two serial force platforms were used to collect postural sway data from each horse on study days −7, 14, 42, and 70. Horses were made to stand stationary on the force platforms under 3 stance conditions: normal square stance, base-narrow placement of the thoracic limbs, and removal of visual cues (blindfolded) during a normal square stance. The mean of 3 consecutive, 10-second trials in each condition was calculated and used for analysis. Results-Displacement of the center of pressure differed significantly depending on the stance condition. Among horses exercised on the underwater treadmill, postural stability in both the base-narrow and blindfolded stance conditions improved, compared with findings for horses exercised on the overground treadmill. Horses exercised on the overground treadmill were only successful at maintaining a stable center of pressure during the normal square stance position. Conclusions and Clinical Relevance-Variations in stance position had profound effects on the mechanics of standing balance in horses with experimentally induced carpal joint osteoarthritis. Underwater treadmill exercise significantly improved the horses’ postural stability, which is fundamental in providing evidence-based support for equine aquatic exercise.

Objective-To determine whether tepoxalin alters kidney function in dogs with chronic kidney disease (CKD). Animals-16 dogs with CKD (International Renal Interest Society stage 2 or 3) and osteoarthritis. Procedures-Kidney function was assessed via serum biochemical analysis, urinalysis, urine protein-to-creatinine concentration ratio, urine γ-glutamyl transpeptidase-to-creatinine concentration ratio, iohexol plasma clearance, and indirect blood pressure measurement twice before treatment. Dogs received tepoxalin (10 mg/kg, PO, q 24 h) for 28 days (acute phase; n = 16) and an additional 6 months (chronic phase; 10). Recheck examinations were performed weekly (acute phase) and at 1, 3, and 6 months (chronic phase). Kidney function variables were analyzed via repeated-measures ANOVA. Results-There was no difference over time for any variables in dogs completing both phases of the study. Adverse drug events (ADEs) resulting in discontinuation of tepoxalin administration included increased serum creatinine concentration (1 dog; week 1), collapse (1 dog; week 1), increased liver enzyme activities (1 dog; week 4), vomiting and diarrhea (1 dog; week 8), hematochezia (1 dog; week 24), and gastrointestinal ulceration or perforation (1 dog; week 26). Preexisting medical conditions and concomitant drug use may have contributed to ADEs. Kidney function was not affected in the latter 5 dogs. Discontinuation of tepoxalin administration stabilized kidney function in the former dog and resolved the ADEs in 4 of the 5 latter dogs. Conclusions and Clinical Relevance-Tepoxalin may be used, with appropriate monitoring, in dogs with International Renal Interest Society stage 2 or 3 CKD and osteoarthritis.

Objective-To assess effects of in vitro meloxicam exposure on metabolism in articular chondrocytes from dogs with naturally occurring osteoarthritis Sample-Femoral head cartilage from 16 dogs undergoing total hip replacement Procedures-Articular cartilage samples were obtained. Tissue sulfated glycosaminoglycan (SGAG), collagen, and DNA concentrations were measured. Collagen, SGAG, chondroitin sulfate 846, NO, prostaglandin E2 (PGE2), and matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, and MMP-13 concentrations in culture medium were analyzed. Aggrecan, collagen II, MMP-2, MMP-3, MMP-9, MMP-13, ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS)-4, ADAMTS-5, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, TIMP-3, interleukin-1β, tumor necrosis factor-α, cyclooxygenase-1, cyclooxygenase-2, and nducible nitric oxide synthase gene expression were evaluated. Comparisons between tissues cultured without (control) and with meloxicam at concentrations of 0.3, 3.0, and 30.0 μg/mL for up to 30 days were performed by means of repeated-measures analysis. Results-Meloxicam had no effect on chondrocyte SGAG, collagen, or DNA concentrations. Expression of ADAMTS-5 was significantly decreased in all groups on all days, compared with the day 0 value. On day 3, culture medium PGE2 concentrations were significantly lower in all meloxicam-treated groups, compared with values for controls, and values remained low. Culture medium MMP-3 concentrations were significantly lower on day 30 than on day 3 in all meloxicam-treated groups. Conclusions and Clinical Relevance-Results suggested that in vitro meloxicam treatment of osteoarthritic canine cartilage for up to 30 days did not induce matrix degradation or stimulate MMP production. Meloxicam lowered PGE2 release from this tissue, and effects on tissue chondrocyte content and matrix composition were neutral.