Longitudinal in vivo cationic contrast-enhanced computed tomography classifies equine articular cartilage injury and repair.

Cationic contrast-enhanced computed tomography (CECT) capitalizes on increased contrast agent affinity to the charged proteoglycans in articular cartilage matrix to provide quantitative assessment of proteoglycan content with enhanced images. While high resolution microCT has demonstrated success, we investigate cationic CECT use in longitudinal in vivo imaging at clinical resolution. We hypothesize that repeated administration of CA4+ will have no adverse side effects or complications, and that sequential in vivo imaging assessments will distinguish articular cartilage repair tissue from early degenerative and healthy cartilage in critically sized chondral defects. In an established equine translational preclinical model, lameness and synovial effusion scores are similar to controls after repeated injections of CA4+ (eight injections over 16 weeks) compared to controls. Synovial fluid total protein, leukocyte concentration, and sGAG and PGE2 concentrations and articular cartilage and synovial membrane scores are also equivalent to controls. Longitudinal in vivo cationic CECT attenuation in repair tissue is significantly lower than peripheral to (adjacent) and distantly from defects (remote sites) by 4 weeks (p < 0.001), and this difference persists until 16 weeks. At the 6- and 8-week time points, the adjacent locations exhibit significantly lower cationic CECT attenuation compared with the remote sites, reflecting peri-defect degeneration (p < 0.01). Cationic CECT attenuation at clinical resolution significantly correlates with cationic CECT (microCT) (r = 0.69, p < 0.0001), sGAG (r = 0.48, p < 0.0001), and ICRS II histology score (r = 0.63, p < 0.0001). In vivo cationic CECT imaging at clinical resolution distinguishes fibrous repair tissue from degenerative and healthy hyaline cartilage and correlates with molecular tissue properties of articular cartilage.

Survey of equine veterinarians regarding primary equine back pain in the United States.

Back pain is a common complaint, clinical finding and performance limiting factor in sport horses. This study sought to gather current veterinary trends in the diagnosis, treatment and management of primary equine back pain in the United States. A 22 question survey was distributed electronically to equine practitioners through AAEP and ACVSMR listservs and through closed social media groups. The survey was open from April 20, 2022 to July 5, 2022. Responses were analyzed using Microsoft excel pivot tables. Ninety-seven survey responses were obtained and analyzed. Respondents reported the clinical signs most frequently relayed to them by the owner/rider/trainer of horses diagnosed with primary back pain were behavioral issues and poor performance. Most common diagnostic tests reported were radiography of the spinous processes, thoraco-lumbar vertebral bodies, and transcutaneous ultrasound of the thoraco-lumbar region. Most common pathologies reported were impinging dorsal spinous processes, degenerative sacro-iliac joint disease, and osteoarthritis in lumbar or thoracic articular process joints. In regards to impinging spinous process ("kissing spine") treatments, 72.2% of respondents recommended surgery only after non-surgical treatments failed, and 14.6% of respondents never recommended surgery. The majority (82%) of respondents reported some level of improvement in clinical signs of primary back pain with rehabilitation alone. To date, there has been no consensus or discussion about common abnormalities, diagnostic tests, treatments or management options for primary equine back pain in the United States. Results of this survey are a starting point showing current trends in diagnosis, treatment and management of primary equine back pain among equine practitioners in the United States showing 82% of practitioners using rehabilitation as a component of treatment.

Blind Versus Ultrasound-Guided Low-Volume Perineural Injection of Tibial and Fibular Nerves in Equine Cadaver Limbs.

Techniques for local anesthesia of the tibial (TN) and superficial and deep fibular nerves (FNs) in horses are well established. Ultrasound-guided perineural blocks can identify the nerve location, reduce the anesthetic volume needed and avoid needle misplacement. The aim of this research was to compare the success of blind perineural injection technique (BLIND) to ultrasound-guided technique (USG). Fifteen equine cadaver hindlimbs were divided into two groups. Perineural injection of the TN and FNs was performed using a mixed solution of radiopaque contrast, saline and food dye. BLIND (n = 8) used 15 mL for the TN and 10 mL for each fibular nerve. USG (n = 7) used 3 mL for the TN and 1.5 mL for each fibular nerve. The limbs were radiographed immediately after injections and sectioned transversally to evaluate the diffusion and presence of the injectate adjacent to the TN and FNs. The presence of dye immediately adjacent to the nerves was considered a successful perineural injection. No statistically significant difference was observed between groups for success. Distal diffusion of injectate following perineural injection of the TN was significantly less for USG compared to BLIND. Proximal, distal and medial diffusion of injectate following perineural injection of FNs was significantly less for USG compared to BLIND. Low-volume USG results in less diffusion but similar success compared to BLIND leaving it up to veterinarian preference when selecting a technique.

Examining the Effects of the Oral Supplement Biota orientalis in the Osteochondral Fragment-Exercise Model of Osteoarthritis in the Horse.

Osteoarthritis (OA) is a common problem in horses. Several oral supplements have been proposed as treatments for horses with OA. The object of this study was to evaluate the use of the oil extract from the seeds of Biota orientalis (BO) for the treatment of experimentally induced OA in horses. OA was induced in 16, 2-5 year old horses in one middle carpal joint on Day 0; the other limb underwent a sham operation. Once daily oral treatment with BO or placebo was initiated on Day 0 and continued to Day 70. All horses were exercised 5 days a week starting on Day 14 through Day 70. The horses were evaluated every other week for lameness and serum GAG concentration as well as weekly synovial fluid assessment. Magnetic resonance imaging was performed on Day 7 and 70. Radiographic changes were assessed on Day 0, 14, and 70. On Day 70 tissue from the middle carpal joint was assessed macroscopically and histologically. All outcome parameters were compared between treatment groups to identify effects of treatment. Compared to placebo a significant decrease was found in synovial fluid prostaglandin E2 concentration and white blood cell counts in horses treated with BO. There was a significant reduction in radiographic scores for subchondral lysis of the radial carpal bone, osteophyte formation, subchondral sclerosis of the radial carpal bone, and total radiographic score for the horses treated with BO. There was no significant difference between treatment groups in clinical lameness findings, MRI findings, macroscopic grading or histologic grading. This study suggests a significant anti-inflammatory effect from oral BO that should be further investigated in clinical OA.

Effects of a Bio-Electromagnetic Energy Regulation Blanket on Thoracolumbar Epaxial Muscle Pain in Horses.

Back pain and inflammation of the epaxial musculature is a significant problem in all equine athletes. Treatment of back pain can be challenging and often requires a multimodal approach. In humans, bio-electromagnetic energy regulation therapy (BEMER) has been reported to be effective in pain modulation. With its increased use in people comes a similar robust application in veterinary medicine unfortunately, there is unsubstantiated evidence for this type of therapy in horses. Objectives of this study were to assess analgesic responses and biomechanical outcome variables using a bio-electromagnetic energy regulation therapy blanket, and to evaluate serum biomarkers as a method to monitor the treatment effects in horses with thoracolumbar epaxial muscle pain. Cohort study of 8 horses treated for 3 consecutive days. Horses with naturally-occurring thoracolumbar epaxial muscle pain were used in this study. Objective outcome variables were recorded daily for 5 days, which included spinal evaluation, mechanical nociceptive thresholds, electromyography, kinematics, kinetics, and serum biomarkers. BEMER blanket therapy significantly improved thoracolumbar epaxial muscle nociceptive thresholds. Center of pressure displacement as a measure of postural stability was significantly improved as well as significant gains in spinal flexibility were demonstrated at study completion. A significant treatment effect was not appreciated in measures of muscle tone, ground reaction forces or serum biomarkers. Limitations include the lack of a control group and a definitive structural diagnosis of thoracolumbar epaxial muscle pain. The BEMER blanket produced significant clinical and biomechanical effects in horses with back pain.

Retrospective analysis of horses with ultrasound evaluation of the sacroiliac region and response to local corticosteroid injection: 42 cases.

Local injection of corticosteroids is commonly performed in horses with sacroiliac (SI) region pain and/or dysfunction, ,and ultrasound findings of normal horses and those with SI pain have also been well described. However, no studies have been performed that have evaluated if ultrasound findings, injection technique, or medications injected affect prognosis for return to function. The objectives of the current study are to determine if findings on ultrasound, injection technique, or medications injected are predictive of return to function in horses with SI region pain and/or dysfunction. Medical records were evaluated for horses that had ultrasound exam of the SI region as well as local injection with corticosteroids. A client survey was sent to determine the horse's return to performance. Logistic regression was performed to determine which variables were predictive of horses with SI pain and/or dysfunction returning to performance. A return to the same or higher level of work was found in 26 of 42 (62%) of horses after SI injections, 4 of 42 (10%) of horses returned to a lower level of work, and 12 of 42 (28%) did not return to work at any level. Horses that were injected with methylprednisolone were 4.2 times more likely to return to performance than horses injected with triamcinolone. Factors evaluated on ultrasound of the SI region did not predict whether a horse would return to performance following SI region injection.

Extracorporeal Shockwave Therapy Increases Growth Factor Release from Equine Platelet-Rich Plasma In Vitro.

INTRODUCTION: Extracorporeal shockwave therapy (ESWT) and platelet-rich plasma (PRP) are common treatments for soft tissue injuries in horses. Shockwave triggers cell specific responses to promote healing. Growth factors released from PRP also promote healing. It has been hypothesized that greater growth factor release would amplify the healing process. The combination of ESWT and PRP could promote healing in injured tendons and ligaments in the horse. The objective of this study was to determine if application of shockwaves to PRP samples increases the concentration of transforming growth factor-ß1 (TGF-ß1) and platelet-derived growth factor ßß (PDGF-ßß) released from the platelets in vitro. MATERIALS AND METHODS: PRP was produced from blood drawn from six horses. The PRP from each horse was exposed to the following treatments: (1) positive control (freeze-thaw cycle), (2) untreated negative control, or shockwaves with either (3) a "standard probe" (ESWT-S) with a 2 cm focal width and medium energy density or (4) a "power probe" (ESWT-P) with a 1 cm focal width and high energy density. After each treatment, the samples were centrifuged, and the supernatant was harvested. The supernatant was then used for growth factor quantification via commercially available ELISA kits for TGF-ß1 and PDGF-ßß. RESULTS: Concentrations of TGF-ß1 and PDGF-ßß in PRP that underwent a freeze-thaw cycle were significantly increased compared with all other treatments. Both ESWT-S and ESWT-P resulted in significantly increased TGF-ß1 concentrations, 46 and 33%, respectively, when compared with the negative control. Both ESWT-S and ESWT-P resulted in significantly increased PDGF-ßß concentrations, 219 and 190%, respectively, when compared with the negative control. DISCUSSION: These data indicate that the application of ESWT to PRP increases the expression of growth factors in vitro. This suggests that the combination therapy of local PRP injection followed by ESWT may stimulate release of growth factors from platelets after they have been injected into the area of injury. CONCLUSION: The combination of PRP and ESWT might result in synergism of two modalities previously utilized individually for tendon and ligament injuries in horses.

A comparison of peritoneal fluid values in mares following bilateral laparoscopic ovariectomy using a vessel sealing and dividing device versus placement of two ligating loops.

The objective of this study was to determine the effect of bilateral laparoscopic ovariectomy on peritoneal fluid values in mares and compare how this effect was modified by the method of ovarian vessel hemostasis used. Ten mares undergoing standing bilateral laparoscopic ovariectomy were used in a randomized clinical study. During surgery, blood vessels within the mesovarium were either: (1) sealed and transected with a vessel sealing and dividing device (VSDD), or (2) ligated using two loops placed proximal to each ovary and then the mesovarium transected using laparoscopic scissors. The ovaries were removed through the ipsilateral body wall. Abdominocentesis was performed before surgery and 24 h and 72 h after surgery. Markers of peritoneal inflammation, as measured by total nucleated cell count, total protein (TP) and red blood cell count via abdominocentesis, were consistently increased for all groups compared to pre-operative values. The mean (range) of TP for the VSDD group was 4.14 (3.9-4.5) g/dL, and that for the ligating loop group was 3.18 (2.7-3.5) g/dL. Use of the VSDD resulted in significantly greater TP concentrations in the abdominal fluid at 24 h and 72 h post-operatively when compared to a ligating loop (P <0.001 and 0.04, respectively).

Urogenital surgery performed with the mare standing.

Many urogenital procedures of the mare are commonly performed with the mare standing. Ovariectomy via colpotomy was described as early as 1903, and the Caslick vulvoplasty was first described in 1937. As knowledge expands and instruments become more specialized, techniques will improve. With the introduction of laparoscopy, clinicians have not only been able to improve the previously described urogenital procedures but also to devise new procedures. This article describes multiple surgeries of the female urogenital tract, all of which can be performed with the mare standing, and describes a variety of approaches to some portions of the female urogenital tract.

Comparison of peritoneal fluid values after laparoscopic cryptorchidectomy using a vessel-sealing device (Ligasure™) versus a ligating loop and removal of the descended testis.

OBJECTIVE: To determine the effect of unilateral laparoscopic cryptorchidectomy and removal of the descended testis on peritoneal fluid values, and to compare effect between 2 methods for cryptorchid testis vessel hemostasis. STUDY DESIGN: Randomized clinical study. ANIMALS: Stallions (n = 10) with unilateral abdominal cryptorchid testis. METHODS: During standing laparoscopic cryptorchidectomy, blood vessels within the mesorchium of the cryptorchid testis were either sealed and transected with the LigaSure Atlas™ or 2 ligating loops were placed proximal to the testis and the tissue transected with laparoscopic scissors. The testis was removed through the body wall. After laparoscopic cryptorchidectomy, stallions were anesthetized and the descended testis was removed using a closed technique leaving the scrotal incision open. Abdominocenteses were performed before surgery, and 24, and 72 hours after surgery. RESULTS: Values for peritoneal total nucleated cell count (TNCC), total protein concentration (TP), and red blood cell count (RBCC) were all elevated at 24 and 72 hours when compared with baseline. Median TNCC for LigaSure™ (59,780 cells/µL) was nearly twice that of the ligating loop (32,880 cells/µL) at 24 hours postoperatively. There was no statistically significant difference in TNCC, TP, or RBCC between groups. CONCLUSIONS: TNCC, TP, and RBCC increase appreciably from baseline 24 hours after laparoscopic cryptorchidectomy and closed castration but are markedly reduced by 72 hours.

Effect of sequential removal of parts of the second metacarpal bone on the biomechanical stability of the equine carpus.

OBJECTIVE: To quantify changes in biomechanical stability and stiffness within the equine carpus after removal of 50%, 80%, and 100% of the second metacarpal bone (MC2). STUDY DESIGN: In vitro biomechanical study. METHODS: Cadaveric equine forelimbs (n = 16) were evaluated. Intact constructs were loaded in axial compression from 0 to 5000 N and compression + torsion (5000 N ± 20°) for 5 cycles. This was repeated after removal of 50%, 80%, and 100% of MC2. The primary biomechanical outcome variables were the compressive stiffness and compressive + torsional stiffness of the carpus. Relative kinematic motion was also evaluated between the second carpal bone (C2) and the radial carpal bone (RC), C2 and the third metacarpal bone (MC3) and C2 and the third carpal bone (C3). RESULTS: A significant decrease in compressive + torsional stiffness was found after 100% removal of MC2. Compressive stiffness of the carpus did not change after 100% MC2 removal. A significant increase in relative rotation around the z-axis (rotation around the long axis) was observed for C2 versus MC3 and C2 versus C3 when 100% of MC2 was removed as compared to 80%, 50%, and 0% removal. No significant difference in relative rotation between C2 and RC was detected. CONCLUSIONS: The biomechanical results reported here suggest that the torsional stability of the equine carpus is significantly decreased only after complete resection of MC2.

Assessment of the tissue diffusion of anesthetic agent following administration of a low palmar nerve block in horses.

OBJECTIVE: To investigate tissue diffusion of anesthetic agent following administration of low palmar nerve blocks (LPBs) in horses. DESIGN: Randomized clinical trial. ANIMALS: 12 adult horses. PROCEDURES: In 9 horses, mepivacaine hydrochloride-iohexol (50:50 dilution) injections were administered bilaterally (2 or 4 mL/site) to affect the medial and lateral palmar and palmar metacarpal nerves (4 sites). Lateral radiographic views of both metacarpal regions were obtained before and at 5, 15, 30, 60, 90, and 120 minutes after block administration; proximal and distal extents of contrast medium (and presumably anesthetic agent) diffusion from palmar and palmar metacarpal injection sites were measured and summed to determine total diffusion. Methylene blue solution was injected in forelimbs of 3 other horses that were subsequently euthanized to determine the potential route of anesthetic agent diffusion to the proximal suspensory ligament region. RESULTS: Mean extents of proximal and total contrast medium diffusion were 4.0 and 6.6 cm, respectively, for the palmar metacarpal nerves and 4.3 and 7.1 cm, respectively, for the palmar nerves. Subtle proximal diffusion secondary to lymphatic drainage was evident in 17 of the 18 limbs. Contrast medium was detected in the metacarpophalangeal joint or within the digital flexor tendon sheath in 8 and 7 limbs, respectively. In the cadaver limbs, methylene blue solution did not extend to the proximal suspensory ligament region. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, LPBs resulted in minimal proximal diffusion of anesthetic agent from the injection sites. Limbs should be aseptically prepared prior to LPB administration because inadvertent intrasynovial injection may occur.