Intravenous magnesium sulfate (MgSO4) is used in equine practice to treat hypomagnesemia, dysrhythmias, neurological disorders, and calcium dysregulation. MgSO4 is also used as a calming agent in equestrian events. Hypercalcemia affects calcium-regulating hormones, as well as plasma and urinary electrolytes; however, the effect of hypermagnesemia on these variables is unknown. The goal of this study was to investigate the effect of hypermagnesemia on blood parathyroid hormone (PTH), calcitonin (CT), ionized calcium (Ca2+), ionized magnesium (Mg2+), sodium (Na+), potassium (K+), chloride (Cl-) and their urinary fractional excretion (F) after intravenous administration of MgSO4 in healthy horses. Twelve healthy female horses of 4-18 years of age and 432-600 kg of body weight received a single intravenous dose of MgSO4 (60 mg/kg) over 5 minutes, and blood and urine samples were collected at different time points over 360 minutes. Plasma Mg2+ concentrations increased 3.7-fold over baseline values at 5 minutes and remained elevated for 120 minutes (P < 0.05), Ca2+ concentrations decreased from 30-60 minutes (P < 0.05), but Na+, K+ and Cl- concentrations did not change. Serum PTH concentrations dropped initially to rebound and remain elevated from 30 to 60 minutes, while CT concentrations increased at 5 minutes to return to baseline by 10 minutes (P < 0.05). The FMg, FCa, FNa, FK, and FCl increased, while urine osmolality decreased from 30-60 minutes compared baseline (P < 0.05). Short-term experimental hypermagnesemia alters calcium-regulating hormones (PTH, CT), reduces plasma Ca2+ concentrations, and increases the urinary excretion of Mg2+, Ca2+, K+, Na+ and Cl- in healthy horses. This information has clinical implications for the short-term effects of hypermagnesemia on calcium-regulation, electrolytes, and neuromuscular activity, in particular with increasing use of Mg salts to treat horses with various acute and chronic conditions as well as a calming agent in equestrian events.

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO4 ) to healthy horses. MgSO4 is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO4 at 60 mg/kg of body weight over 5 min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg2+ ). Objective data were analyzed using the Wilcoxon rank-sum test with p < .05 used as a determination for significance. Plasma concentrations of Mg2+ increased nearly fivefold, ionized calcium (Ca2+ ) decreased by nearly 10%, and the Ca2+ to Mg2+ ratio declined more than 3.5-fold and remained different than baseline until 24 hr (p < .05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca2+ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO4 .

Chapter 4 Lameness of the Distal Limb NAVICULAR REGION/PALMAR FOOT Randy B. Eggleston, Randy B. EgglestonSearch for more papers by this authorGary M. Baxter, Gary M. BaxterSearch for more papers by this authorJames Belknap, James BelknapSearch for more papers by this authorAndy Parks, Andy ParksSearch for more papers by this authorKaty Dern, Katy DernSearch for more papers by this authorAshlee E. Watts, Ashlee E. WattsSearch for more papers by this authorMatt Brokken, Matt BrokkenSearch for more papers by this authorKyla F. Ortved, Kyla F. OrtvedSearch for more papers by this authorAlicia L. Bertone, Alicia L. BertoneSearch for more papers by this author Randy B. Eggleston, Randy B. EgglestonSearch for more papers by this authorGary M. Baxter, Gary M. BaxterSearch for more papers by this authorJames Belknap, James BelknapSearch for more papers by this authorAndy Parks, Andy ParksSearch for more papers by this authorKaty Dern, Katy DernSearch for more papers by this authorAshlee E. Watts, Ashlee E. WattsSearch for more papers by this authorMatt Brokken, Matt BrokkenSearch for more papers by this authorKyla F. Ortved, Kyla F. OrtvedSearch for more papers by this authorAlicia L. Bertone, Alicia L. BertoneSearch for more papers by this author Book Editor(s):Gary M. Baxter VMD, MS, DIPLOMATE ACVS, Gary M. Baxter VMD, MS, DIPLOMATE ACVS Associate Dean for Clinical Services Director Veterinary Teaching Hospital, University of Georgia, Athens, GA, USASearch for more papers by this author First published: 12 May 2020 https://doi.org/10.1002/9781119276715.ch4 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary Navicular disease or syndrome remains one of the most controversial and common causes of intermittent forelimb lameness in horses between 4 and 15 years of age. It is estimated that the syndrome is responsible for one-third of all chronic forelimb lameness in horses. Navicular disease/syndrome has been defined as a chronic forelimb lameness associated with pain arising from the navicular bone and closely related structures including the collateral suspensory ligaments of the navicular bone, distal sesamoidean impar ligament, navicular bursa, and the deep digital flexor tendon. With the vascular theory, thrombosis of the navicular arteries within the navicular bone, partial or complete occlusion of the digital arteries at the level of the pastern and fetlock, and a reduction in the distal arterial blood supply due to atherosclerosis was thought to result in ischemia of the navicular bone. Adams and Stashak's Lameness in Horses, Seventh Edition RelatedInformation

Background There is a need to improve therapies for osteoarthritis in horses. Objectives To assess the efficacy of equine allogeneic chondrogenic-induced mesenchymal stem cells combined with equine allogeneic plasma as a novel therapy for osteoarthritis in horses. Study design Randomised, double-blinded, placebo-controlled experiment. Methods In 12 healthy horses, osteoarthritis was induced in the metacarpophalangeal joint using an osteochondral fragment-groove model. Five weeks after surgery, horses were randomly assigned to either an intra-articular injection with chondrogenic-induced mesenchymal stem cells + equine allogeneic plasma (= intervention) or with 0.9% saline solution (= control). From surgery until the study end, horses underwent a weekly joint and lameness assessment. Synovial fluid was collected for cytology and biomarker analysis before surgery and at Weeks 5, 5 + 1d, 7, 9 and 11. At Week 11, horses were subjected to euthanasia, and the metacarpophalangeal joints were evaluated macroscopically and histologically. Results No serious adverse events or suspected adverse drug reactions occurred during the study. A significant improvement in visual and objective lameness was seen with the intervention compared with the control. Synovial fluid displayed a significantly higher viscosity and a significantly lower glycosaminoglycan concentration in the intervention group. Other biomarkers or cytology parameters were not significantly different between the treatment groups. Significantly less wear lines and synovial hyperaemia were present in the intervention group. The amount of cartilage oligomeric matrix protein, collagen type II and glycosaminoglycans were significantly higher in the articular cartilage of the intervention group. Main limitations This study assessed the short-term effect of the intervention on a limited number of horses, using an osteoarthritis model. This study also included multiple statistical tests, increasing the risk of type 1 error. Conclusions Equine allogeneic chondrogenic-induced mesenchymal stem cells combined with equine allogeneic plasma may be a promising treatment for osteoarthritis in horses. The is available in Spanish - see Supporting Information

The objective of this study was to characterize the pharmacokinetics and pharmacodynamics of intravenous administration of magnesium sulfate to horses using a novel radio-telemetry system for physiologic signal capture. Five Horses were surgically implanted with a radio-telemetric carotid catheter. Implants were paired with a non-invasive telemetric unit which acquired a six lead ECG and 3-axis acceleration to assess activity acquired wirelessly in real-time for future analysis. Horses were exposed to a new stall environment before (baseline) and after 60 mg/kg (30 mL) of magnesium sulfate (MgSO4), or the same volume of 0.9% saline, administered intravenously in a blinded, random crossover design. Blood for pharmacokinetics, telemetric data, and body temperature were recorded serially for 24 h. Data were analyzed across time and between treatments. Significance was set at P < 0.05. Ionized magnesium concentration (Mg2+) increased and the Ca2+ to Mg2+ ratio decreased and persisted for 5 h after MgSO4 administration. Heart rate (HR) increased and mean arterial blood pressure (MAP) decreased for at least 6 h. Electrocardiogram (ECG) intervals (RR) decreased and (PR and QTc) increased in duration compared to controls indicating an increase in heart rate, and slower myocardial conduction in the MgSO4 group. Acceleration in all planes was less in the MgSO4 group compared to controls indicating decreased locomotion. This novel method permitted collection of physiologic signals without interference by handlers or animal restraint. An intravenous bolus of MgSO4 produced cardiac variable changes associated with the reduction of locomotion in these horses, and in a direction that may be causal. Locomotion was decreased when horses were first introduced into a new environment which reflects the calming effect desired in sport horses. Telemetric monitoring can be used as a model to elucidate the behavior and physiologic effects of other drugs. The administration of MgSO4 may be detected for regulatory purposes with the monitoring of Mg2+ and Ca2+ concentrations and their ratio.

BACKGROUND:Manual palpation of rabbit spine levels has been used to assess fusion status. This method of testing is subject to inter-observer differences in assessment. We attempted to quantify fusion based on the amount of movement between rabbit vertebrae at the level of fusion.METHODS:Rabbits were divided into three groups. The first underwent a sham surgery; the second underwent a unilateral spinal fusion; and the third underwent a bilateral spinal fusion. All groups were sacrificed at either 5- or 10-week post-procedure. Each spine was tested for fusion using standard manual palpation techniques. The spines were also placed on a specially designed apparatus and moved through 10°, 20°, and 30° of extension/flexion.RESULTS:Out of 10 rabbits, 2 underwent sham surgery, 2 underwent a fusion procedure at L4-L5 and 6 underwent a fusion at L5-L6. We only included rabbits that underwent a L5-L6 fusion surgery. Our apparatus did not always rotate the spine the intended amount with up to 30% error. When rabbits graded as fused were compared to sham rabbits, there was a trend towards reduction in percent of overall measured angle within the fused group as compared to the sham group (8.77% vs. 13.84%, P=0.14).CONCLUSIONS:Our model attempted to quantify the amount of displacement between vertebrae during the manual palpation exam. There is a trend towards reduced measured angle between vertebrae between fused and non-fused spines and no statistically significant difference in overall measured angle between unilaterally and bilaterally fused spines.

This chapter describes the fractures of the distal phalanx in foals. Distal phalanx fractures are classified into seven types depending on breed and type of athletic activity. Palmar process fractures are nonarticular fractures of the palmar or plantar process of the distal phalanx. Parasagittal oblique fractures are oblique, articular fractures of the palmar or plantar process of the distal phalanx. Sagittal or axial fractures are articular midsagittal fractures of the distal phalanx. Extensor process fractures are articular fracture fragments involving variable portions of the extensor process of the distal phalanx. Comminuted fractures are comminuted or multiple, and generally secondary to osteomyelitis and sequestra formation. Solar margin fractures are nonarticular solar margin fractures of the distal phalanx. Palmar process fractures in foals are nonarticular fractures of the palmar or plantar process of the distal phalanx. The treatment of fractures of the distal phalanx depends on the fracture type.

OBJECTIVE To evaluate lameness and morphological changes associated with an osteochondral fragment-groove procedure as a means of experimental induction of metacarpophalangeal (MCP) joint osteoarthritis within an 11-week period in horses. ANIMALS 6 nonlame adult warmbloods. PROCEDURES The right MCP joint of each horse underwent an osteochondral fragment-groove procedure (day 0). After 1 week of stall rest (ie, starting day 7), each horse was trained daily on a treadmill. Weekly, horses underwent visual and inertial sensor-based assessments of lameness. Both MCP joints were assessed radiographically on days 0 (before surgery), 1, 35, and 77. A synovial fluid sample was collected from the right MCP joint on days 0 (before surgery), 35, 36, 49, 63, and 77 for cytologic and biomarker analyses. On day 77, each horse was euthanized; both MCP joints were evaluated macroscopically and histologically. RESULTS Right forelimb lameness was detected visually and by the inertial sensor system when horses were moving on a straight line after distal forelimb flexion or circling left on days 14 to 77. Compared with presurgical values, synovial fluid interleukin-6, prostaglandin E2, hyaluronic acid, and interleukin-1 receptor antagonist protein concentrations were increased at 2 or 3 time points, whereas tumor necrosis factor-α and interleukin-10 concentrations were decreased at 1 time point. Gross examination of all right MCP joints revealed synovitis and wear lines; synovitis was confirmed histologically. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a combined osteochondral fragment-groove procedure can be used to induce clinically and grossly observable early MCP joint osteoarthritis during an 11-week period in horses.

Objective The aim of this study was to evaluate the injection of a bone substitute material (BSM) into an impact lesion in the palmar condyle of the third metacarpal bone. Study Design This was anin vivocontrolled study performed on six horses. Materials and Methods Medial metacarpal condyles were exposed via arthrotomy and a compressive lesion created in anaesthetized horses using 80 psi (27.6 MPa) onto the articular surface (n = 12). Paired limbs were randomly selected as a control or for extra-articular injection of BSM towards the subchondral bone near the compressive lesion. Parameters of the surgical techniques and BSM distribution outcomes were evaluated using magnetic resonance imaging analysis, histology and histomorphometry. Results Injection of the BSM required significant pressure, as well as the use of a pilot hole. The BSM was visible in all magnetic resonance imagings in treatment limbs. Post-impact treatment limbs had greater average grey scale values than controls (p = 0.041), and greater average grey scale values than pre-impact treatment limbs (p = 0.004). Histology demonstrated haemorrhage and microfractures at the site of compression with no evidence of bone disruption from BSM injection. Conclusion Injection of BSM into the dense subchondral bone of the equine palmar condyle could be targeted to a site of injury, distributed subchondrally and without further injury to bone or cartilage. Clinical Significance This procedure has potential for the treatment of clinical impact injury or osteoarthritis in horses, and long-term studies are warranted.

Background: Currently, platelet-poor plasma (PPP) is a discarded waste product of platelet-rich plasma (PRP) and may contain valuable proteins. Purpose/Hypothesis: The study’s goal was to evaluate the concentration of plasma as a potential additive biotherapy for the treatment of osteoarthritis. We hypothesized that a novel polyacrylamide concentration device would efficiently concentrate insulin-like growth factor–1 (IGF-1) from PPP and be additive to PRP or autologous protein solution (APS). Study Design: Descriptive laboratory study. Methods: A laboratory study was conducted with human and equine whole blood from healthy volunteers/donors. Fresh samples of blood and plasma were processed and characterized for platelet, white blood cell, and growth factor/cytokine content and then quantified by enzyme-linked immunosorbent assays specific for IGF-1, transforming growth factor–β, interleukin-1β, and interleukin-1 receptor antagonist as representatives of cartilage anabolic and inflammatory mediators. Results: A potent cartilage anabolic protein, IGF-1, was significantly concentrated by the polyacrylamide concentration device in both human and equine PPP. The polyacrylamide device also substantially increased plasma proteins over whole blood, most dramatically key proteins relevant to the treatment of osteoarthritis, including transforming growth factor–β (29-fold over blood) and interleukin-1 receptor antagonist (70-fold over plasma). Conclusion: Concentrated PPP is a unique source for biologically relevant concentrations of IGF-1. PRP and APS can produce greater concentrations of other anabolic and anti-inflammatory proteins not found in plasma. Clinical Relevance: The polyacrylamide device efficiently concentrated PPP to create a unique source of IGF-1 that may supplement orthopaedic biologic therapies.

Osteoarthritis (OA) is a progressive disease associated with cartilage injury and its inherently limited repair capability. Synovium-based cellular constructs (sConstructs) are proposed as possible treatments. Equine sConstructs were produced from decellularized synovium-based extracellular matrix scaffolds (sECM) seeded with synovium-derived mesenchymal stem cells (sMSC), and engineered to express green fluorescent protein (GFP), or bone morphogenetic protein-2 (BMP-2). Survival, distribution, and chondrogenic potential of the sConstructs in vitro and in vivo were assessed. sConstructs in co-culture with chondrocytes increased chondrocyte proliferation, viability, and Col II production, greatest in BMP-2-sConstructs. Chondrocyte presence increased the production of hyaluronic acid (HA), proteoglycan (PG), and BMP-2 by the sConstructs in a positive feedback loop. sECM alone, or GFP- or BMP-2-sConstructs were implanted in synovium adjacent to clinically created full-thickness rat-knee cartilage lesions. At 5 weeks, the lesion area and implants were resected. Gross anatomy, adjacent articulate cartilage growth and subchondral bone repair were scored; and peripheral, central and cartilage lesion measurements taken. For all scores and measurements, sConstruct implants were significantly greater than controls, greatest with the BMP-2-sConstructs. Immunohistochemistry demonstrated migration of endogenous cells into the sECM, with greater cellularity in the constructs with intense positive GFP staining confirming engraftment of implanted sMSC and continued gene expression. In summary, exposing cartilage to sConstructs was chondrogenic in vitro and in vivo, and resulted in substantially increased growth in vivo. This effect was mediated, in part, by soluble ECM and cell factors and upregulation of anabolic growth proteins, such as BMP-2. This work is "proof of concept" that sConstructs surgically implanted adjacent to cartilage damage can significantly improve cartilage and subchondral bone repair, and potentially prevent the progression of OA.

s of the Special Session at the ACVS Surgical Summit; American College of Veterinary Sports Medicine and Rehabilitation Annual Meeting. October 26, 2018, Phoenix, AZ, USA.

OBJECTIVE To create a bioactive synovium scaffold by infusing decellularized synovial-derived extracellular matrix (synECM) with synovial-derived mesenchymal stem cells (synMSCs). SAMPLE Synovium from the femoropatellar and medial femorotibial joints of equine cadavers. PROCEDURES The synMSCs were cultured in monolayer and not treated or cotransduced to enhance expression of green fluorescent protein (GFP) and human bone morphogenetic protein (BMP)-2. The synECM was decellularized with 0.1% peracetic acid and then seeded with synMSCs (0.5 × 106 cells/0.5 mL) by use of a 30% serum gradient. Samples were evaluated on days 0, 3, 7, and 14. Cell migration, differentiation, and distribution into the synECMs were determined by cell surface marker CD90, viability, histologic morphology, and fluorescence microscopy results and expression of GFP, BMP-2, hyaluronan (HA), and proteoglycan (PG). RESULTS At day 14, synMSCs were viable and had multiplied 2.5-fold in the synECMs. The synECMs seeded with synMSCs had a significant decrease in CD90 expression and significant increases in HA and PG expression. The synECMs seeded with synMSCs cotransduced with GFP, or BMP-2 had a significant increase in BMP-2 expression. CONCLUSIONS AND CLINICAL RELEVANCE The synECM seeded with synMSCs or synMSCs cotransduced with GFP, or BMP-2 yielded a bioactive synovial scaffold. Expression of BMP-2 by synMSCs cotransduced to enhance expression of BMP-2 or GFP and an accompanying increase in both HA and PG expression indicated production of anabolic agents and synoviocyte differentiation in the scaffold. Because BMP-2 can promote repair of damaged cartilage, such a bioactive scaffold could be useful for treatment of injured cartilage.

Concentration of functional proteins has used methods such as dialysis, precipitation, and freeze-drying, which are poorly scalable, not compatible with cell viability, and often damages proteins. Currently, platelet-poor-plasma (PPP) is a discarded waste product of platelet-rich plasma (PRP) and may contain valuable chondrogenic proteins. PURPOSE: to determine the efficiency of a novel patient-side method of concentrating plasma and platelet- and white blood cell (WBC)-rich plasma as a potential adjunctive therapy for OA. METHODS: A laboratory study was conducted, with IRB and IACUC approval, using residual human clinical plasma (PPP) and equine blood samples. Samples and products were characterized for platelet, WBC, and total protein content then quantified by enzyme-linked immunosorbent assays specific to IGF-1, TGF- ß, IL-1ra, and IL-1 ß as anabolic and inflammatory mediators to cartilage. RESULTS: Plasma total and IGF-1 protein were concentrated by the device in both human (P<0.001) and equine (P<0.0001) plasma. TGF- ß, IL-1 and IL-1ra were very low in plasma. The polyacrylamide concentrator device highly concentrated platelets, WBCs, and plasma proteins over PRP and whole blood, most dramatically TGF- ß (P<0.001; 29-fold over blood) and IL-1ra (P<0.001; 70-fold over plasma) resulting in a > 2000-fold increase in IL-1/Il-1ra ratio over plasma (P<0.001) and 1668-fold increase over PRP (P<0.001). Interestingly, patients with OA had a lower anabolic protein profile (IGF-1 and TGF- ß) and a higher inflammatory-related protein profile (IL-1 ß and IL-1ra) compared to healthy equine athletes without OA. This work identified concentrated plasma as a unique resource for IGF-1 not found in PRP and that further protein concentration of PRP can produce greater platelet proteins such as TGF- ß and greater anti-inflammatory proteins such as IL-1ra. CONCLUSION: the polyacrylamide device efficiently concentrated plasma and PRP proteins and is commercially available as an injectable biotherapy.

Magnesium sulfate (MgSO4 ) was administered to calm competition horses. We evaluated the impact of regulatory requirements for the handling of blood samples on plasma ionized magnesium (iMg), ionized calcium (iCa), the iMg to iCa ratio, and pH. We hypothesized that iCa, iMg. and iMg/iCa would be similar among storage and collection methods. Four blood samples were collected from each of 50 horses on the same day: Group 1 - collection in a heparinized syringe and processed within hours in a clinical laboratory; Group 2 - collection into a plasma separator tube (PST) centrifuged just prior to analysis, and plasma processed as in (1); Group 3 - collection into a PST, refrigerated, shipped via overnight carrier to the United States Equestrian Federation (USEF) Equine Drug Testing and Research laboratory, centrifuged just prior to analysis, and plasma processed; and Group 4 - as in Group 3, but stored frozen at -80°C for 90 days, thawed, and plasma processed as in Group 3. Results for iMg/iCa are unit-less, adjusted iMg for potential influence of plasma protein and iCa, and highly correlated with iMg pH (r = -.933; P < 0.01). Samples processed immediately in a clinical reference laboratory had the greatest iMg/iCa. Both iMg/iCa and pH predictably decreased after freezing (P < 0.001). These data suggest that the iMg/iCa mirrors alterations in iMg regardless of storage and collection methods. This understanding can facilitate the development of a regulatory threshold for the control of the nefarious use of magnesium sulfate in competing horses, and an understanding of potential changes to iMg/iCa with storage of B samples.

Objective To assess if injection of allogeneic dental pulp tissue particles would improve lameness in horses with naturally occurring osteoarthritis (OA) or soft tissue (ST) injury. Design Prospective, randomized, blinded, and controlled clinical trial and client survey assessment. Animals Forty lame client-owned horses. Procedures Sterile dental pulp, recovered from otherwise healthy foals that perish during dystocia, was processed under good manufacturing processing to produce mechanically manipulated, unexpanded pulp tissue particles containing viable cells surrounded in extracellular matrix. Forty lame client-owned horses with confirmed OA (n = 20), or ST injury (desmitis or tendonitis) received a 2 mL intra-articular (n = 20 OA) or intra-lesional (n = 20) injection of control transport vehicle (n = 20) or 10 × 106 dental pulp tissue particles (n = 20). Acclimatized horses had baseline measurements performed and were then injected on day 0. Horses were treadmill exercised for 2 weeks, evaluated by clinical parameters, lameness score, edema (score and circumference), pain on flexion (OA) or pressure (ST), and clients’ scores for pain and discomfort before and through 45 days after pulp injection. Twenty horses were available for >2.5-year follow-up. Results Pulp-treated horses showed decrease in lameness compared to baseline (P < 0.009) or placebo controls (P < 0.013) for at least 2 weeks. Client assessments of comfort were improved between before and 45 days after pulp injection (P < 0.001). Clinical improvement with ST injury was significantly greater than OA (P < 0.001). At >2.5-year follow-up, at least 10 horses were in work. Conclusion and clinical relevance Dental pulp tissue particles can be considered as a treatment option for equine lameness due to OA, desmitis, or tendonitis.

Selective inhibition of Cathepsin K (CatK) has a promising therapeutic potential for diseases associated with bone loss and osseous inflammation, such as osteoarthritis, periodontitis, and osteoporosis. In horses, stress-related bone injuries are common and accompanied by bone pain and inflammation resulting in excessive bone resorption and periostitis. VEL-0230 is a highly selective inhibitor of CatK that significantly decreased bone resorption and increased bone formation biomarkers. The goal of this study was to demonstrate the presence of CatK in equine bone and a simultaneous influence on the bone marrow cellular components including function and differentiation. Our objectives were: 1) to investigate the tissue localization of CatK protein in equine bone using immunohistochemistry, and 2) to determine the effect of CatK inhibition on osteoclastogenic, chondrogenic and osteogenic differentiation potential of equine stem and progenitor cells in vitro using histochemical staining and differentiation-related gene expression analyses. Bone biopsies, harvested from the tuber coxae and proximal phalanx of six healthy horses, were processed for immunostaining against CatK. Sternal bone marrow aspirates were cultured in 0, 1, 10, or 100 μM of VEL-0230 and subsequent staining scoring and gene expression analyses performed. All cells morphologically characterized as osteoclasts and moderate number of active bone lining osteoblasts stained positive for CatK. Histochemical staining and gene expression analyses revealed a significant increase in the osteoclastogenic, chondrogenic and osteogenic differentiation potential of equine bone marrow cells, which was VEL-0230-concentration dependent for the latter two. These results suggested that CatK inhibition may have anabolic effects on bone and cartilage regeneration that may be explained as a feedback response to CatK depletion. In conclusion, the use of CatK inhibition to reduce inflammation and associated bone resorption in equine osseous disorders may offer advantages to other therapeutics that would require further study.

OBJECTIVE To investigate effects of hyaluronic acid (HA) or HA combined with chondroitin sulfate (CS) and N-acetyl-d-glucosamine (NAG) by use of a lipopolysaccharide (LPS) in vitro method. SAMPLE Monolayer cultures of synovial cells from 4 adult horses. PROCEDURES Synovial cell cultures were untreated or treated with HA alone or HA-CS-NAG for 24 hours, subsequently unchallenged or challenge-exposed with 2 LPS concentrations (20 and 50 ng/mL) for 2 hours, and retreated with HA or HA-CS-NAG for another 24 hours. Cellular morphology of cultures was evaluated at 0, 24 (before LPS), 26 (after LPS), and 50 (24 hours after end of LPS) hours. At 50 hours, cell number and viability and prostaglandin (PG) E2, interleukin (IL)-6, matrix metalloproteinase (MMP)-3, and cyclooxygenase (COX)-2 production were measured. RESULTS LPS challenge exposure induced a significant loss of characteristic synovial cell morphology, decrease in cell viability, and increases in concentrations of PGE2, IL-6, MMP-3, and COX-2. Cells treated with HA or HA-CS-NAG had significantly better viability and morphology scores and lower concentrations of PGE2, MMP-3, IL-6, and COX-2 than untreated LPS challenge-exposed cells. Cells treated with HA had significantly better morphology scores at 50 hours than cells treated with HA-CS-NAG. Cells treated with HA-CS-NAG had significantly superior suppression of LPS-induced production of PGE2, IL-6, and MMP-3 than cells treated with HA alone. CONCLUSIONS AND CLINICAL RELEVANCE HA and HA-CS-NAG protected synovial cells from the effects of LPS. Treatment with HA-CS-NAG had the greatest anti-inflammatory effect. These results supported the protective potential of HA and HA-CS-NAG treatments.

There are several animal models routinely used for study of the spinal fusion process and animal selection largely depends on the scientific question to be answered. This review outlines the advantages and disadvantages of various animal models used to study spinal fusion and describes the New Zealand White (NSW) rabbit which is the most popular preclinical model to study spinal fusion. We outline critical steps required in planning and performing spinal fusion surgery in this model. This includes determination of the required animal number to obtain statistical significance, an outline of appropriate technique for posterolateral fusion and other components of completing a study. As advances in drug delivery move forward and our understanding of the cascade of gene expression occurring during the fusion process grows, performing and interpreting preclinical animal models will be vital to validating new therapies to enhance spinal fusion.