Histologic and cytologic changes in normal equine joints after injection with 2.5% injectable polyacrylamide hydrogel reveal low-level macrophage-driven foreign body response.

OBJECTIVE: The data presented in this paper are derived from an in vivo study performed to characterize the nature of the synovial integration process of a 2.5% synthetic cross-linked injectable polyacrylamide hydrogel (2.5 iPAAG) injected IA in horses. ANIMALS: 10 healthy horses not suffering from OA or signs of joint disease were administered 50 or 100 mg 2.5 iPAAG in a total of 13 metacarpophalangeal or middle carpal joints. METHODS: Injected joints were examined at 0, 14, 42, and/or 90 days postinjection. Parameters investigated included clinical examination, synoviocentesis, gross pathology, histology, and scanning electron microscopy. RESULTS: All horses remained clinically normal, with no adverse events recorded throughout the study period. Gross postmortem did not reveal any significant findings. Arthrocentesis cytology parameters remained within clinically normal levels throughout the study. Synovial histology demonstrated that cellular infiltration of macrophages, villus hyperplasia, and vascularization were significantly higher in 2.5 iPAAG-injected joints compared to controls. Scanning electron microscopy confirmed that the 2.5 iPAAG demonstrated an extensive tissue integration as a 3-D scaffolding structure with intact cross-linked strands. CLINICAL RELEVANCE: Results confirm that an IA injection of 2.5 iPAAG induces a typical foreign body response that is predominately macrophage driven with no evidence of fibrosis or mineralization. Integration of the gel is evident by 14 days, with no free gel remaining in the joint cavity at this time.

Histological tissue healing following high-power laser treatment in a model of suspensory ligament branch injury.

BACKGROUND: High-power laser therapy gained popularity recently as a regenerative treatment for tendinitis and desmitis in the horse. However, studies evaluating the effects of laser therapy on tissue repair at the histological level in large mammals are lacking. OBJECTIVES: To evaluate the effects of high-power laser therapy on suspensory desmitis healing, using a model of suspensory ligament branch injury. STUDY DESIGN: In vivo experiments. METHODS: Standardised lesions were surgically induced in all four lateral suspensory branches of 12 healthy Warmblood horses. Laser therapy (class 4, 15W) was applied daily on two of four induced lesions for four consecutive weeks. Horses were randomly assigned to either short-term study (horses were sacrificed after 4 weeks) or long-term study (6 months). Suspensory ligament samples were scored after staining with haematoxylin-eosin and immunostaining for collagen 1- collagen 3- and factor VIII. RESULTS: In the short-term study, significantly better (lower) scores for variation in density (17% above cut-off score in treated lesions vs. 31% above cut-off score in controls, P = .03), shape of nuclei (54% vs 92%, P = .02), fibre alignment (32% vs 75%, P = .003) and fibre structure (38% vs 71%, P = .02) were found in laser-treated lesions when compared to controls. Collagen 3 expression was significantly higher (32% vs 19%, P = .006) in control lesions. In both short- and long-term studies combined, parameters lesion size (44% vs 56%, P = .02) and shape of nuclei (53% vs 84%, P = .05) scored significantly better in treated lesions. Long-term, significantly better (lower) scores were found in the laser-treated group for lesion size (15% vs 45%, P = .008) and a higher percentage above cut-off score for density of the nuclei (27% vs 9%, P = .02), compared to controls. MAIN LIMITATIONS: The model of suspensory branch injury is not an exact representation of clinical overstrain lesions. CONCLUSIONS: These results suggest that high-power laser therapy enables better lesion healing than conservative treatment.

Movement asymmetries in horses presented for prepurchase or lameness examination.

BACKGROUND: The increasing popularity of objective gait analysis makes application in prepurchase examinations (PPE) a logical next step. Therefore, there is a need to have more understanding of asymmetry during a PPE in horses described on clinical evaluation as subtly lame. OBJECTIVES: The objective of this study is to objectively compare asymmetry in horses raising minor vet concerns in a PPE and in horses raising major vet concerns with that found in horses presented with subtle single-limb lameness, and to investigate the effect of age/discipline on the clinicians' interpretation of asymmetry on the classification of minor vet concerns in a PPE. STUDY DESIGN: Clinical case-series. METHODS: Horses presented for PPE (n = 98) or subjectively evaluated as single limb low-grade (1-2/5) lame (n = 24, 13 forelimb lame, 11 hindlimb lame), from the patient population of a single clinic, were enrolled in the study provided that owners were willing to participate. Horses undergoing PPE were assigned a classification of having minor vet concerns (n = 84) or major vet concerns (n = 14) based on findings during the dynamic-orthopaedic part of the PPE. Lame horses were only included if pain-related lameness was confirmed by an objective improvement after diagnostic analgesia exceeding daily variation determined for equine symmetry parameters using optical motion capture. Clinical evaluation was performed by six different clinicians, each with ≥8 years of equine orthopaedic experience. Vertical movement symmetry was measured using optical motion capture, simultaneously with the orthopaedic examination. Data were analysed using previously described parameters and mixed model analysis and least squares means were used to calculate differences between groups. RESULTS: There was no effect of age or discipline on the levels of asymmetry within PPE horses raising minor vet concerns. MinDiff and RUD of the head discriminated between forelimb lame and PPE horses raising minor vet concerns; MinDiff, MaxDiff, RUD of the Pelvis, HHDswing and HHDstance did so for hindlimb lameness. Two lameness patterns differentiated both forelimb and hindlimb lame from PPE horses with minor vet concerns: RUD Poll + MinDiff Withers - RUD Pelvis and RUD Pelvis + RUD Poll - MinDiff Withers. Correcting for vertical range of motion enabled differentiation of PPE horses with minor vet concerns from PPE horses with major vet concerns. MAIN LIMITATIONS: Objective data only based on trot on soft surface, limited number of PPE horses with major vet concerns. CONCLUSIONS: Combinations of kinematic parameters discriminate between PPE horses with minor vet concerns and subtly lame horses, though overlap exists.

Visual lameness assessment in comparison to quantitative gait analysis data in horses.

BACKGROUND: Quantitative gait analysis offers objective information to support clinical decision-making during lameness workups including advantages in terms of documentation, communication, education, and avoidance of expectation bias. Nevertheless, hardly any data exist comparing outcome of subjective scoring with the output of objective gait analysis systems. OBJECTIVES: To investigate between- and within-veterinarian agreement on primary lame limb and lameness grade, and to determine relationships between subjective lameness grade and quantitative data, focusing on differences between (1) veterinarians, (2) live vs video assessment, (3) baseline assessment vs assessment following diagnostic analgesia. STUDY DESIGN: Clinical observational study. METHODS: Kinematic data were compared to subjective lameness assessment by clinicians with ≥8 years of orthopaedic experience. Subjective assessments and kinematic data for baseline trot-ups and response to 48 diagnostic analgesia interventions in 23 cases were included. Between and within-veterinarian agreement was investigated using Cohen's Kappa (κ). Asymmetry parameters for kinematic data ('forelimb lame pattern', 'hindlimb lame pattern', 'overall symmetry', 'vector sum head', 'pelvic sum') were determined, and used as outcome variables in mixed models; explanatory variables were subjective lameness grade and its interaction with (1) veterinarian, (2) live or video evaluation and (3) baseline or diagnostic analgesia assessment. RESULTS: Agreement on lame limb between live and video assessment was 'good' between and within veterinarians (median κ = 0.64 and κ = 0.53). There was a positive correlation between subjective scoring and measured asymmetry. The relationship between lameness grade and objective asymmetry differed slightly between (1) veterinarians (for all combined parameters, p-values between P < .001 and 0.04), (2) between live and video assessments ('forelimb lame pattern', 'overall symmetry', both P ≤ .001), and (3) between baseline and diagnostic analgesia assessment (all combined parameters, between P < .001 and .007). MAIN LIMITATIONS: Limited number of veterinarians (n = 4) and cases (n = 23), only straight-line soft surface data, different number of subjective assessments live vs from video. CONCLUSIONS: Overall, between- and within-veterinarian agreement on lame limb was 'good', whereas agreement on lameness grade was 'acceptable' to 'poor'. Quantitative data and subjective assessments correlated well, with minor though significant differences in the number of millimetres, equivalent to one lameness grade between veterinarians, and between assessment conditions. Differences between baseline assessment vs assessment following diagnostic analgesia suggest that addition of objective data can be beneficial to reduce expectation bias. The small differences between live and video assessments support the use of high-quality videos for documentation, communication, and education, thus, complementing objective gait analysis data.

High-Power Laser Therapy Improves Healing of the Equine Suspensory Branch in a Standardized Lesion Model.

High-power laser therapy is often used as a treatment for human sport injuries but controlled standardized studies on its efficacy are lacking. The technique has also been introduced in the equine field and recently promising results were reported in a retrospective study focusing on 150 sporthorses suffering from tendinopathy and desmopathy of the SDFT, DDFT, suspensory ligament, and suspensory branches. The goal of the present study was to evaluate the effect of high-power laser in a standardized lesion model in horses. Lesions were created in all lateral suspensory branches of 12 warmblood horses. In each horse, 2 of the 4 lesioned branches were treated daily with a multi-frequency high-power laser for 4 weeks. Color Doppler ultrasonography was performed during and after the treatment period. Six horses were euthanized 4 weeks post-surgery (short-term) and 6 were further rehabilitated until 6 months and then euthanized (long-term). High-field MRI evaluation was performed on all cadaver limbs. On ultrasound, transverse size of the lesion was significantly smaller after 2- and 3 months (p = 0.026 and p = 0.015) in the treated branches. The expected post-surgery enlargement of the lesion circumference and cross-sectional area (CSA) over time, was significantly lower in the short-term laser treated group (p = 0.016 and p = 0.010). Treated lesions showed a significantly increased Doppler signal during treatment (p < 0.001) compared with control. On MRI, in the short and long-term group, the CSA of the lesions was significantly smaller (p = 0.002), and the mean signal significantly lower in the treatment groups (p = 0.006). This standardized controlled study shows that multi-frequency high-power laser therapy significantly improves healing of a suspensory branch ligament lesion.

Postoperative complications in equine elective, clean orthopaedic surgery with/without antibiotic prophylaxis.

OBJECTIVE: Retrospective analysis of postoperative complications in equines after clean, orthopaedic surgical procedures in order to detect differences between animals treated with antibiotics and horses without receiving these drugs. MATERIAL AND METHODS: Details on 652 patients, surgical procedures and surgery-associated complications were compiled from horses being operated between June 2011 and January 2015. Antibiotic-receiving patients (n = 259) were tested for differences in complication rates and characteristics to controls (n = 393). RESULTS: The total complication rate was 39.1 %. Increased swelling was observed most often (25.6 %), followed by exudation (7.5 %), fever without incisional alterations (2.3 %), suture dehiscence (1.8 %), and seroma (0.8 %). Seven patients (five treated, two controls) developed septic arthritis within a total of 463 arthroscopies (1.5 %). There were no significant differences in the development of postoperative complications, which were seen in 97/259 (37.5 %) antibiotic receiving patients and in 158/393 (40.2 %) controls. The application of perioperative antibiotics was significantly influenced by surgeon (p < 0.0001) and type of surgery (p = 0.0007) and increased with the number of surgical lesions (p = 0.03). In patients undergoing tendovaginoscopy/ bursoscopy, fasciotomy and neurectomy (n = 98), antibiotic prophylaxis was initiated less frequently than in other surgeries, e. g. combinations of surgeries, splint bone extraction, tenotomy, and arthroscopy (n = 554). CONCLUSION: Severe complications in equine clean orthopaedic surgery are rare and complication rates in patients either receiving perioperative antibiotics or not were not significantly different. CLINICAL RELEVANCE: Based on the results the use of antibiotics appears to be non-essential in uncomplicated elective orthopaedic interventions in the horse.

An international multi-centre prospective study on the efficacy of an intraarticular polyacrylamide hydrogel in horses with osteoarthritis: a 24 months follow-up.

BACKGROUND: Polyacrylamide hydrogel (PAAG) was evaluated recently to treat osteoarthritis (OA) in horses with highly encouraging results; however no long term field-study was done to explore its clinical efficacy and lasting effect. The objective of this study was to evaluate the efficacy of PAAG in improving clinical signs of OA in horses. We hypothesized that lameness grade would significantly improve and the effect would last at least 2 years in osteoarthritic joints treated with PAAG. Forty three horses older than 2 years with OA in only one joint based on clinical evaluation, intra-articular anaesthesia and imaging (radiography) were included in this study. Horses were injected with 2 ml of PAAG into the affected joint and were followed up at 1, 3, 6, 12 and 24 months. Efficacy of PAAG was evaluated by blinded clinical assessment of lameness. Adverse reactions to joint injection were assessed. Data relating to case details, type of activity, joint and limb involved, lameness duration, lameness grading, previous joint treatment, joint effusion grading, radiographic grading, and owner assessment were recorded. Factors associated with the outcome measure "lameness grading" were analyzed using generalized linear mixed model for logistic regression. RESULTS: At 1, 3, 6, 12 and 24 months follow-up, 59%, 69%, 79%, 81/% and 82.5% of horses were non-lame respectively. Reduction of joint effusion was observed over time. No side effect was observed in the treated joints. There was a significant decrease in lameness grade from baseline to 1, 3, 6, 12 and 24 months (P < 0.0001) and a significant positive association with joint effusion (P < 0.0001). Estimates for odds ratio (OR) showed that the effect of treatment increased over time (OR for lower lameness from month 1 to month 24 relative to baseline increased from 20 to 58). CONCLUSIONS: PAAG significantly alleviated lameness and joint effusion in osteoarthritic joints. PAAG is a safe and lasting (at least 24 months) OA treatment in horses. PAAG is a promising new treatment for OA in horses.

The influence of temperature and age on the T1 relaxation time of the equine distal limb.

The extent of fat suppression using short tau inversion recovery (STIR) imaging is variable between horses. Our aim was to determine if patient's age and/or hoof temperature have an influence on the T(1) relaxation time of bone marrow in the equine distal limb, thereby affecting the suppression of fat signal. Magnetic resonance imaging was conducted on standing horses and cadaver samples using a low-field magnet (0.27 T). The hoof temperature was measured at the lateral side of the coronary band. A modified inversion recovery fast spin-echo (IR-FSE) sequence was used to measure the signal intensity for a range of inversion times (TIs) at six different regions of interest (ROI): (1) distal aspect of the proximal phalanx, (2) proximal aspect of the middle phalanx, (3) distal aspect of the middle phalanx, (4) navicular bone, (5) proximal aspect of the distal phalanx, and (6) distal aspect of the distal phalanx. The T(1) of the bone marrow in the equine distal limb was calculated from the results and was found to increase by 3.13 ± 0.08 (SE) ms/°C. There was no significant effect of age (2-16 years) but the T(1) values measured from the limbs of young (< 1 year) animals were considerably longer (32.6 ± 1.7 (SE) ms). Similar effects of temperature and age were found for all measured ROIs but there were significant differences in the mean values of T(1) , ranging from +7.7 (distal aspect of the distal phalanx) to -13.2 ms (distal aspect of the proximal phalanx).