Computed tomography and fluoroscopy versus radiographic guidance for internal fixation of simulated dorsomedial-plantarolateral central tarsal bone fractures in nonracehorses.

OBJECTIVE: The aim of this study was to assess screw placement in simulated dorsomedial-plantarolateral central tarsal bone (CTB) fractures using two imaging guidance techniques - computed tomography (CT) with fluoroscopy compared to digital radiography alone (DR). STUDY DESIGN: Experimental study. SAMPLE POPULATION: Equine cadaver hindlimbs (n = 10 pairs). METHODS: One tarsus per pair was randomly assigned to have a 4.5 mm cortical screw placed across the CTB using CT and fluoroscopy (CT/F group) or digital radiography alone (DR group). Postoperative CT was performed on all limbs. Variables related to marker placement, procedure time, and screw positioning were recorded and compared using a paired t-test for dependent means (p < .05). RESULTS: Time for marker placement was longer for the CT/F group (p = .001), with no difference in total procedure time (p = .12). CT/F was not superior to radiography alone (p > .05) for parameters related to screw positioning. Based on the 95% CI, there was greater range in relative screw length using radiography (76.5%-91.2%) versus CT/F (78.4%-84.0%). CONCLUSION: Internal fixation of CTB fractures can be successfully performed using either technique for imaging guidance. CT and fluoroscopy did not result in faster or more accurate screw placement compared to radiographs alone, except in determining screw length. CLINICAL SIGNIFICANCE: Mild adjustments in fluoroscopic or radiographic angle appeared to be a point of variability in the perception of screw placement. While CT is recommended for improved understanding of fracture configuration and surgical planning, radiographic guidance may be a suitable alternative for internal fixation of dorsomedial-plantarolateral fractures.

Serotype-specific transduction of canine joint tissue explants and cultured monolayers by self-complementary adeno-associated viral vectors.

A formal screening of self-complementary adeno-associated virus (scAAV) vector serotypes in canine joint tissues has not been performed to date. Selecting appropriate serotypes is crucial for successful treatment due to their varying levels of tissue tropism. The objective of this study is to identify the most optimal scAAV vector serotype that maximizes transduction efficiencies in canine cell monolayer cultures (chondrocytes, synoviocytes, and mesenchymal stem cells) and tissue explant cultures (cartilage and synovium). Transduction efficiencies of scAAV serotypes 1, 2, 2.5, 3, 4, 5, 6, 8, and 9 were evaluated in each culture type in three different vector concentrations by encoding a green fluorescent protein. It was found that scAAV2 and 2.5 showed the overall highest transduction efficiency among serotypes with dose-response. Since possible immune response against conventional AAV2 was previously reported in dogs, the chimeric scAAV2.5 may be more suitable to use. Evaluation of the safety and efficacy of the scAAV2.5 vector with an appropriate therapeutic gene in vivo is indicated.

Antimicrobial Properties of Equine Stromal Cells and Platelets and Future Directions.

Increasing antimicrobial resistance in veterinary practice has driven the investigation of novel therapeutic strategies including regenerative and biologic therapies to treat bacterial infection. Integration of biological approaches such as platelet lysate and mesenchymal stromal cell (MSC) therapy may represent adjunctive treatment strategies for bacterial infections that minimize systemic side effects and local tissue toxicity associated with traditional antibiotics and that are not subject to antibiotic resistance. In this review, we will discuss mechanisms by which biological therapies exert antimicrobial effects, as well as potential applications and challenges in clinical implementation in equine practice.

Integrating data types to estimate spatial patterns of avian migration across the Western Hemisphere.

For many avian species, spatial migration patterns remain largely undescribed, especially across hemispheric extents. Recent advancements in tracking technologies and high-resolution species distribution models (i.e., eBird Status and Trends products) provide new insights into migratory bird movements and offer a promising opportunity for integrating independent data sources to describe avian migration. Here, we present a three-stage modeling framework for estimating spatial patterns of avian migration. First, we integrate tracking and band re-encounter data to quantify migratory connectivity, defined as the relative proportions of individuals migrating between breeding and nonbreeding regions. Next, we use estimated connectivity proportions along with eBird occurrence probabilities to produce probabilistic least-cost path (LCP) indices. In a final step, we use generalized additive mixed models (GAMMs) both to evaluate the ability of LCP indices to accurately predict (i.e., as a covariate) observed locations derived from tracking and band re-encounter data sets versus pseudo-absence locations during migratory periods and to create a fully integrated (i.e., eBird occurrence, LCP, and tracking/band re-encounter data) spatial prediction index for mapping species-specific seasonal migrations. To illustrate this approach, we apply this framework to describe seasonal migrations of 12 bird species across the Western Hemisphere during pre- and postbreeding migratory periods (i.e., spring and fall, respectively). We found that including LCP indices with eBird occurrence in GAMMs generally improved the ability to accurately predict observed migratory locations compared to models with eBird occurrence alone. Using three performance metrics, the eBird + LCP model demonstrated equivalent or superior fit relative to the eBird-only model for 22 of 24 species-season GAMMs. In particular, the integrated index filled in spatial gaps for species with over-water movements and those that migrated over land where there were few eBird sightings and, thus, low predictive ability of eBird occurrence probabilities (e.g., Amazonian rainforest in South America). This methodology of combining individual-based seasonal movement data with temporally dynamic species distribution models provides a comprehensive approach to integrating multiple data types to describe broad-scale spatial patterns of animal movement. Further development and customization of this approach will continue to advance knowledge about the full annual cycle and conservation of migratory birds.

Current use of biologic therapies for musculoskeletal disease: A survey of board-certified equine specialists.

OBJECTIVE: To evaluate the use of mesenchymal stem cells (MSCs), autologous conditioned serum (ACS), platelet-rich plasma (PRP), and autologous protein solution (APS) for the treatment of equine musculoskeletal disease by diplomates of the American College of Veterinary Surgery (ACVS), and American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR). STUDY DESIGN: Cross-sectional study. SAMPLE POPULATION: Diplomates (n = 423). METHODS: An email link was sent to ACVS and ACVMR diplomates. A survey contained 59 questions regarding demographics, as well as indications, frequency, adverse effects, and limitations of use. Responses were analyzed using Fisher's exact test. RESULTS: One hundred and fifty four surveys were analyzed. Years in practice and type of practice were not associated with biologic therapy use. PRP was the most used therapy (120/137; 87.5%). PRP and MSCs were most often administered intralesionally while ACS and APS were most often administered intra-articularly. ACS (50/104; 48.1%) treatment was repeated commonly within 2 weeks of initial injection. MSCs (39/90; 43.3%) and PRP (38/100; 38%) were commonly repeated 1-2 months after initial injection and APS was typically repeated >4 months after initial injection (21/53; 39.6%). Local inflammation and expense were the most common adverse effect and limitation of use. CONCLUSION: Diplomates most commonly utilized PRP and MSC intralesionally for soft-tissue injuries, and ACS and ACP intra-articularly for joint injury. Protocols for repeated administration varied widely. Local inflammation was a clinical concern with the use of biologics. CLINICAL SIGNIFICANCE: Biologic therapies are used commonly by ACVS and ACVSMR diplomates for soft tissue and joint disease.

Toll-like receptor activation of equine mesenchymal stromal cells to enhance antibacterial activity and immunomodulatory cytokine secretion.

OBJECTIVE: To evaluate effects of Toll-like and nucleotide-binding oligomerization domain (NOD)-like receptor (TLR, NLR) ligand stimulation of equine mesenchymal stromal cells (MSCs) on antibacterial and immunomodulatory properties in vitro. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Equine bone-marrow-derived MSCs (three horses). METHODS: MSCs were stimulated with TLR (polyinosinic:polycytidylic acid [pIC] and lipopolysaccharide [LPS]) and NLR agonists (γ-d-Glu-mDAP [IE-DAP]) for 2 h, and plated at 1 × 105 cells/well 24 h. MSC-conditioned media (MSC-CM) were collected and assessed for antimicrobial peptide cathelicidin/LL-37 production, bactericidal action against multidrug-resistant planktonic and biofilm Staphylococcus aureus and neutrophil phagocytosis. Bacterial growth was measured by plating bacteria and counting viable colonies, reading culture absorbance, and live-dead staining with confocal microscopy imaging. Following initial comparison of activating stimuli, TLR3-agonist pIC protocols (cell density during activation and plating, culture time, %serum) were further optimized for bactericidal activity and secretion of interleukin-8 (IL-8), monocyte-chemoattractant-protein (MCP-1), and cathelicidin/LL37. RESULTS: MSCs stimulation with pIC (p = .004) and IE-DAP (p = .03) promoted increased bactericidal activity, evidenced by reduced viable planktonic colony counts. PIC stimulation (2 × 106 cells/ml, 2 h, 10 µg/ml) further suppressed biofilm formation (p = .001), enhanced neutrophil bacterial phagocytosis (p = .009), increased MCP-1 secretion (p < .0001), and enhanced cathelicidin/LL-37 production, which was apparent when serum concentration in media was reduced to 1% (p = .01) and 2.5% (p = .05). CONCLUSION: TLR-3 pIC MSCs activation was most effective to enhance antibacterial and cytokine responses, which were affected by serum reduction. CLINICAL SIGNIFICANCE: In vitro TLR-3 activation of equine MSCs tested here may be a strategy to improve antibacterial properties of MSCs to treat antibiotic-resistant infections.

Susceptibility of canine chondrocytes and synoviocytes to antibiotic cytotoxicity in vitro.

OBJECTIVE: To evaluate relative cytotoxicity of antibiotics to normal canine joint tissues in vitro. STUDY DESIGN: Experimental in vitro study. SAMPLE POPULATION: Chondrocytes and synoviocytes (three dogs); cartilage explants (three dogs); six dogs total. METHODS: Chondrocytes and synoviocytes from normal femoropatellar joints of three dogs were plated on 24-well plates (50 000 cells/cm2 , triplicate, 48 hours) and exposed to antibiotics (ampicillin sulbactam, vancomycin, cefazolin, ceftazidime, amikacin, enrofloxacin; 0.39-25 mg/mL, 24 hours). Viability was assessed by using trypan blue dye exclusion. Antibiotic concentrations at which 50% cell death occurred (half-maximal inhibitory concentration) were determined to rank antibiotics for relative cytotoxicity. Occurrence of caspase-3 expression after antibiotic exposure was assessed as an indication of apoptosis induction. Cartilage explants from three different dogs were minced and exposed to antibiotics (amikacin, ceftazidime, cefazolin, enrofloxacin; 5 mg/mL, 72 hours). Live/dead staining was performed, and fluorescence was visualized by using confocal microscopy. Percentage of live vs dead cells was quantitated. RESULTS: Viability of chondrocytes and synoviocytes decreased with increasing antibiotic concentrations. Half-maximal inhibitory concentrations were determined for synoviocytes (vancomycin 13.77, ampicillin sulbactam 3.07, amikacin 2.26, ceftazidime 1.62, cefazolin 1.48, enrofloxacin 1.25 mg/mL) and chondrocytes (vancomycin 8.65, ampicillin sulbactam 8.63, ceftazidime 3.16, amikacin 2.74, cefazolin 1.67, enrofloxacin 0.78 mg/mL). Caspase-3 expression was upregulated, providing evidence that apoptotic pathways were active in cell death. CONCLUSION: Half-maximal inhibitory concentration data provided evidence of lower toxicity of vancomycin and ampicillin sulbactam to joint tissues in vitro. CLINICAL SIGNIFICANCE: These results provide evidence to justify future in vitro work with osteoarthritic joint tissues and in vivo clinical trials to evaluate safety and efficacy of intra-articular antibiotics to treat dogs with septic arthritis.

USE OF INTRACARPAL INTERLEUKIN RECEPTOR ANTAGONIST PROTEIN (IRAP) AND HYALURONIC ACID IN A MULTIMODAL THERAPEUTIC REGIME FOR OSTEOARTHRITIS IN AN ASIAN ELEPHANT (ELEPHAS MAXIMUS).

An approximately 41-yr-old female Asian elephant (Elephas maximus) experiencing forelimb stiffness and decreased range of motion was diagnosed with bilateral carpal osteoarthritis (OA). Standing sedation combined with local anesthesia was used to deliver ultrasound-guided carpal articular injections of an autologous conditioned serum product, interleukin receptor antagonist protein, combined with hyaluronic acid. Within 2 mo of completing therapy, improved range and speed of motion were evident. Reduced inflammation was suggested by decreased carpal articular prostaglandin E2 levels. Subjectively improved clinical signs lasted approximately 5-6 mo, at which point carpal articular injections were repeated. Joint inflammatory markers were useful in gauging response to treatment and may provide guidance in the diagnostic and therapeutic approach to elephant OA. On the basis of the positive response noted, interarticular autologous therapy combined with hyaluronic acid should be considered for carpal OA in elephants.

Long-term outcome after stifle arthroscopy in 82 Western performance horses (2003-2010).

OBJECTIVE: To report the outcome of horses engaged in Western performance disciplines after stifle arthroscopy and identify prognostic factors for return to performance. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: Eighty-two Western performance horses undergoing stifle arthroscopy. METHODS: Medical records were reviewed for horses involved in athletic performance/training for various Western performance disciplines and undergoing arthroscopy for lameness localized to the stifle. Follow-up was obtained ≥2 years postoperatively by telephone interviews with the owners. Preoperative and intraoperative findings as well as postoperative treatment were analyzed for their association with return to athletic performance as the primary outcome of interest. RESULTS: The most common disciplines represented were cutting (n = 38), Western pleasure (n = 13), and reining (n = 13). Approximately 40% (32/82) of horses returned to intended use after surgery. Increased age, higher degree of lameness, longer duration of lameness, and the presence of partial-thickness cartilage lesions decreased the odds of returning to athletic performance. Postoperative therapies (intra-articular: stem cells, corticosteroids, interleukin-1 receptor antagonist protein, hyaluronic acid/polysulfated glycosaminoglycans; systemic: nonsteroid anti-inflammatory drugs, hyaluronic acid/polysulfated glycosaminoglycans, oral joint supplements) did not affect the odds of returning to intended use. CONCLUSION: Less than half of the Western performance horses that underwent stifle arthroscopy returned to intended use. Older age, longer duration of lameness, and presence of partial-thickness cartilage lesions affected the odds of a horse returning to intended use. Postoperative therapies did not affect the outcome in this population. CLINICAL SIGNIFICANCE: The prognosis of Western performance horses undergoing stifle arthroscopy is as guarded as that previously reported in horses of other disciplines.

Proceedings of the signature series symposium "cellular therapies for orthopaedics and musculoskeletal disease proven and unproven therapies-promise, facts and fantasy," international society for cellular therapies, montreal, canada, may 2, 2018.

The Signature Series Symposium "Cellular Therapies for Orthopaedics and Musculoskeletal Disease Proven and Unproven Therapies-Promise, Facts and Fantasy" was held as a pre-meeting of the 26th International Society for Cellular Therapy (ISCT) annual congress in Montreal, Canada, May 2, 2018. This was the first ISCT program that was entirely dedicated to the advancement of cell-based therapies for musculoskeletal diseases. Cellular therapies in musculoskeletal medicine are a source of great promise and opportunity. They are also the source of public controversy, confusion and misinformation. Patients, clinicians, scientists, industry and government share a commitment to clear communication and responsible development of the field. Therefore, this symposium convened thought leaders from around the world in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value to patients with musculoskeletal conditions.

Pancarpal and partial carpal arthrodesis with 3 locking compression plates in 6 horses.

OBJECTIVE: To report the outcome of horses after pancarpal or partial carpal arthrodesis with 3 locking compression plates (LCP). STUDY DESIGN: Case series. ANIMALS: Six horses ranging in age from 8 months to 16 years and weighing 227-580 kg with severe carpal pathology including acute fractures, chronic osteoarthritis, and chronic angular limb deformity. METHODS: Pancarpal or partial carpal arthrodesis was performed with 3 LCP. Autologous cancellous bone grafts were used in 5 of 6 cases to facilitate joint arthrodesis. RESULTS: External coaptation was maintained for 4 to 6 weeks after surgery. Radiographic follow-up was available in all 6 cases, all of which reached arthrodesis and pasture soundness by 4-5 months postoperatively. One case required implant removal at 6 months because of implant exposure through the skin but returned to pasture soundness after removal. CONCLUSION: Carpal instability due to acute fractures or chronic disease was successfully stabilized with 3 short LCP, leading to pasture soundness in all 6 horses. CLINICAL SIGNIFICANCE: The use of 3 short LCP should be considered as a strategy to facilitate pancarpal or partial carpal arthrodesis by providing superior stability without placement of implants in the diaphysis of the radius and third metacarpus.

Not Missing the Future: A Call to Action for Investigating the Role of Regenerative Medicine Therapies in Pediatric/Adolescent Sports Injuries.

In August 2016, a group including sport medicine clinicians, researchers, and a bioethicist met in Vail, Colorado to discuss regenerative medicine and its potential role in youth sports injuries. There was consensus that a call to action is urgently needed to understand the current evidence base, the risks and rewards, and future directions of research and clinical practice for regenerative medicine therapies in youth sports. We present here a summary of our meeting, which was supported by the National Youth Sports Health and Safety Institute (NYSHSI), a partnership between the American College of Sports Medicine (ACSM) and Sanford Health. The group's goal is to educate practitioners and the public, and to pioneer a means of accumulating meaningful clinical data on regenerative medicine therapies in pediatric and adolescent athletes.

COMPARISON BETWEEN COMPUTED TOMOGRAPHIC ARTHROGRAPHY, RADIOGRAPHY, ULTRASONOGRAPHY, AND ARTHROSCOPY FOR THE DIAGNOSIS OF FEMOROTIBIAL JOINT DISEASE IN WESTERN PERFORMANCE HORSES.

The femorotibial joints are a common source of lameness in Western performance horses. The objective of this prospective study was to compare the radiography, ultrasonography, computed tomographic arthrography (CTA), and arthroscopy findings in horses with lameness localized to the femorotibial joints. Twenty-five stifles in 24 horses were included and were evaluated with all four of these diagnostic methods. Defects detected in femorotibial joint structures were compared between diagnostic methods using a McNemar's test to evaluate for disagreement. Cranial medial meniscotibial desmopathy was most detected on arthroscopy (in 14/25 cases) and was only detected on ultrasonography in three out of 11 (27.3%) arthroscopically observed cases, but was detected on CTA in nine out of 12 (75%) arthroscopically observed cases. Medial meniscal injury located on the craniolateral border was most detected on arthroscopy (n = 9) and was detected on CTA in five cases, but on ultrasonography in 0 cases. Detection of articular cartilage defects on the medial femoral condyle was most detected with arthroscopy (24/25, 96% cases) and was also detected on CTA in 12/20 (60%) cases with a significant disagreement identified between modalities (P = 0.02). Cranial and caudal cruciate ligament defects were detected on CTA in 6/22 (27.3%) and 7/19 (36.8%) cases, respectively, and with arthroscopy in 3/25 (12%) and 2/25 (8%) cases, respectively. The use of CTA detected more defects in the cruciate ligaments, proximal tibia, and ligament entheses than the other diagnostic methods, but was not reliable for detection of articular cartilage damage on the medial femoral condyle.

Radiofrequency Probe and Sharp Transection for Tenoscopic-Guided Desmotomy of the Accessory Ligament of the Superficial Digital Flexor Tendon.

OBJECTIVE: To compare intra and postoperative clinical features of desmotomy of the accessory ligament of the superficial digital flexor tendon (ALSDFT) using the Saber radiofrequency (SaberRF) electrosurgical probe versus sharp transection with a tenotomy knife. STUDY DESIGN: Randomized, controlled, blocked (horse) design. ANIMALS: Adult horses (n = 6). METHODS: Each horse received bilateral, tenoscopic-guided ALSDFT desmotomy with a SaberRF and tenotomy knife, randomly assigned to left, or right limb. The desmotomy duration and intraoperative hemorrhage grades were recorded. Postoperatively, the grades for surgical incision, carpal sheath effusion, carpal range of motion, flexion pain, and lameness were recorded. Light microscopy using hematoxylin and eosin, and viability staining were performed on the ALSDFT, flexor carpi radialis tendon, radial head of the deep digital flexor tendon, and the deep digital flexor tendon. Variables were compared between desmotomy methods with a paired t-test, Wilcoxon signed rank test, or a repeated measures mixed model. Statistical significance was set at P < .05. RESULTS: Desmotomy of the ALSDFT was completed in all horses. Only mild hemorrhage was observed and not different between methods (SaberRF 2/5 limbs; tenotomy knife 5/6 limbs, P = .078). Carpal sheath effusion was greater for SaberRF at Day 1 (P = .019) but not different from tenotomy knife at any later time. There was no significant difference between methods for viability staining or other measured outcomes. CONCLUSIONS: Tenoscopic-guided ALSDFT desmotomy with the SaberRF probe showed no difference in measured outcomes to sharp transection with a tenotomy knife and minimal collateral tissue damage was observed.

Clinical outcome after intra-articular administration of bone marrow derived mesenchymal stem cells in 33 horses with stifle injury.

OBJECTIVE: To report outcome of horses with femorotibial lesions (meniscal, cartilage or ligamentous) treated with surgery and intra-articular administration of autologous bone marrow derived mesenchymal stem cells (BMSCs). STUDY DESIGN: Prospective case series. ANIMALS: Horses (n = 33). METHODS: Inclusion criteria included horses that had lameness localized to the stifle by diagnostic anesthesia, exploratory stifle arthroscopy and subsequent intra-articular administration of autologous BMSCs. Case details and follow-up were gathered from medical records, owner, trainer or veterinarian. Outcome was defined as returned to previous level of work, returned to work, or failed to return to work. RESULTS: Follow-up (mean, 24 months) was obtained; 43% of horses returned to previous level of work, 33% returned to work, and 24% failed to return to work. In horses with meniscal damage (n = 24) a higher percentage in the current study (75%) returned to some level of work compared to those in previous reports (60-63%) that were treated with arthroscopy alone, which resulted in a statistically significant difference between studies (P = .038). Joint flare post injection was reported in 3 horses (9.0%); however, no long-term effects were noted. CONCLUSIONS: Intra-articular administration of BMSC postoperatively for stifle lesions appeared to be safe, with morbidity being similar to that of other biologic agents. Improvement in ability to return to work may be realized with BMSC treatment compared to surgery alone in horses with stifle injury.

Review of cellular therapies provides new insights into the potential treatment of diverse neurologic diseases in horses and dogs.

Neurological diseases and injuries in veterinary patients (horses, dogs, and cats) are complex, and effective treatment options are limited. Neuronal loss, damage to nerve conduction pathways, and inflammation and scarring associated with spinal cord injury pose major challenges in managing many neurological diseases. Furthermore, most of these neuropathologies lack definitive pharmacological treatments, driving interest and research into novel interventions. Our objective is to provide a narrative review of the current literature surrounding cellular therapies including neuronal and glial stem cells, neurotrophic factors, mesenchymal stem or stromal cells, and cells derived from induced pluripotent stem cells for the treatment of diverse neurological pathologies. Cellular therapies have the potential for cellular replacement, immune modulation, and paracrine signaling and the flexibility of being used alone or alongside surgical intervention. Mesenchymal stem or stromal cells are arguably the most researched cellular therapy and have been administered intrathecally, IV, intra-arterially, intranasally, and intraspinally with few adverse reactions. Limited clinical and experimental studies have suggested efficacy in diseases including acute spinal cord injury and intervertebral disc disease. Little is currently known about the safety and efficacy of neural stem cells, precursor cell administration, and induced pluripotent stem cell-derived treatments. Further research is necessary to determine the efficacy and long-term safety of cellular therapies. Future aims should include larger controlled clinical trials in companion animals for common neurologic conditions including acute spinal cord injury, intervertebral disc disease, peripheral nerve injury, degenerative neuropathies, and age-associated cognitive decline.

Subchondral bone sequestrum formation in the proximal intra-articular and osteochondral region of the third metatarsal bone of an Appaloosa mare treated for septic arthritis.

OBJECTIVE: To raise awareness of the potential for intra-articular subchondral bone sequestrum formation secondary to a traumatic or septic process to enable more rapid identification of this uncommon but possible outcome in future cases. ANIMAL: A client-owned 12-year-old Appaloosa mare. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The mare had a wound to the lateral aspect of the fourth metatarsal bone (MT4) that communicated with the distal tarsal joints. Radiographs revealed a displaced, comminuted fracture of MT4. TREATMENT AND OUTCOME: The horse underwent aggressive debridement of the wound and MT4 as well as, on 2 occasions, needle joint lavage. Systemic, regional, and IA antibiotic therapy was also performed together with a bone graft from the tuber coxae. The horse's comfort improved, and the wound appeared to be healing. Five weeks following discharge, the horse re-presented with a non-weight-bearing lameness and radiographs revealed marked osteomyelitis of the tarsometatarsal and distal intertarsal joints. Postmortem examination of the limb identified a sequestrum within the proximal articular surface of the third metatarsal bone. CLINICAL RELEVANCE: The present report highlights the importance of arthroscopic lavage to visualize the cartilage surface and the benefits of advanced imaging to detect associated changes within the bone earlier than conventional radiographs. To our knowledge, no reports exist of intra-articular subchondral bone sequestra in the tarsometatarsal joint in horses.

Targeted transcriptomic analysis of synovial tissues from horses with septic arthritis treated with immune-activated mesenchymal stromal cells reveals induction of T-cell response pathways.

OBJECTIVE: To investigate mechanistically the reported beneficial effects of immune-activated mesenchymal stromal cell (MSC) therapy to treat equine septic arthritis, leveraging Nanostring technology. ANIMALS: 8 Quarter Horses with induced tibiotarsal Staphylococcus aureus septic arthritis treated IA with either Toll-like receptor-3 agonist polyinosinic:polycytidylic acid-activated MSCs + vancomycin antimicrobials (TLR-MSC-VAN; n = 4) or antimicrobials (VAN; 4). METHODS: Synovial tissues were collected and fixed in neutral-buffered 10% formalin, and formalin-fixed paraffin-embedded synovial and osteochondral tissues were sequenced using a custom-designed 200-gene equine Nanostring nCounter immune panel to directly quantify expression of key immune and cartilage-related genes. Immunohistochemistry to detect CD3+ T cells was performed on synovial tissues to further quantify T-cell infiltration in TLR-MSC-VAN- versus VAN-treated joints. RESULTS: Comparison of synovial transcriptomes between groups revealed moderate changes in differential gene expression, with upregulated expression of 9 genes and downregulated expression of 17 genes with fold change ≥ 2 or ≤ -2 and a significant false discovery rate-adjusted P value of ≤ .05. The most upregulated genes in TLR-MSC-VAN-treated horses included those related to T-lymphocyte recruitment and function, while pathways related to innate immune activation and inflammation were significantly downregulated. Immunohistochemistry and quantitation of CD3+ T-cell infiltrates revealed a numerically greater infiltrate in synovial tissues of TLR-MSC-VAN-treated horses, which did not reach statistical significance in this small sample set (P = .20). CLINICAL RELEVANCE: Targeted transcriptomic analyses using an equine Nanostring immune and cartilage health panel provided new mechanistic insights into how innate and adaptive immune cells within synovial tissues respond to TLR-activated MSC treatment when used to treat septic arthritis.

Fasting horses perioperatively decreases manure production and increases time to manure output postoperatively: a controlled randomized trial.

OBJECTIVE: To compare 3 perioperative feeding regimens and their effect on anesthetic complications, manure output, and colic proportion in healthy horses. METHODS: 45 horses presenting for elective orthopedic procedures were randomly assigned to 1 of 3 groups: not fasted (NF; continuous access to hay perioperatively), fasted muzzled (FM; 10-hour preoperative fast with slow refeeding postoperatively and muzzle placement), or fasted not muzzled (FNM; same as FM without muzzle placement). Anesthetic protocol was standardized. Outcomes compared between groups included anesthesia time, arterial oxygenation, duration of hypotension, perioperative manure output, time to first passage of manure postoperatively, pain scores, and colic proportion. Comparisons were made with a mixed model and Fisher exact test with statistical significance considered at P ≤ .05. RESULTS: No differences were seen in pain scores, oxygenation, hypotension, or colic between groups. Groups FM and FNM had a significantly greater mean reduction in postoperative manure weight (-81% and -70%; P = .003) and number of manure piles (-63% and -55%; P = .005) compared to group NF (-39% and -22%; P < .001; weight and piles, respectively). Mean ± SD minutes to passage of manure postoperatively was significantly shorter in group NF (238 ± 13 minutes) than groups FM (502 ± 174 minutes; P < .001) and FNM (444 ± 171 minutes; P = .003). CLINICAL RELEVANCE: Horses with continuous access to hay prior to and following recovery from anesthesia passed more manure and passed manure sooner after surgery than their fasted counterparts without detrimental effect on anesthetic parameters and postoperative complications. Continuous access to hay perioperatively supports manure production in healthy horses without increase in anesthetic complications.

IL-1ra gene therapy in equine osteoarthritis improves physiological, anatomical, and biological outcomes of joint degeneration.

OBJECTIVE: To evaluate the effects of a gene transfer approach to IL-1ß inhibition in an equine osteochondral chip fragment model of joint injury using a self-complementary adeno-associated virus with interleukin receptor antagonist transgene cassette (scAAVIL-1ra), as posttraumatic osteoarthritis in horses, similar to people, is a significant clinical problem. ANIMALS: 16 horses were utilized for the study. METHODS: All horses had an osteochondral chip fragment induced arthroscopically in one middle carpal joint while the contralateral joint was sham operated. Eight horses received either scAAVIL-1ra or saline in the osteoarthritis joint. Horses were evaluated over 70 days clinically (lameness, imaging, and biomarker analysis) and euthanized at 70 days and evaluated grossly, with imaging and histopathology. RESULTS: The following findings were statistically significant. Injection of scAAVIL-1ra resulted in high synovial fluid levels of IL-1ra (0.5 to 9 µg/mL) throughout the duration of the experiment (70 days). Over the duration, we observed scAAVIL-1ra to improve lameness (lameness score relative improvement of 1.2 on a scale of 0 to 5), cause suppression of prostaglandin E2 (a relative decline of 30 pg/mL), and result in histological improvement in articular cartilage (decreased chondrocyte loss and chondrone formation) and subchondral bone (less osteochondral splitting and osteochondral lesions). Within the synovial membrane of scAAVIL-1ra-treated joints, we also observed perivascular infiltration with CD3-positive WBCs, suggesting lymphocytic T-cell perivascular infiltration commonly observed with viral transduction. CLINICAL RELEVANCE: These data provide support for further evaluation and optimization of scAAVIL-1ra gene therapy to treat equine osteoarthritis.