Cervical stabilization with polyaxial pedicle screw and rod construct in horses: A proof of concept study.

OBJECTIVE: To evaluate safety and efficacy of a novel technique for cervical stabilization. STUDY DESIGN: In vivo experimental. ANIMALS: Four normal adult quarterhorse crossbreed horses (2-4 years of age, > 250 kg). METHODS: One mid-cervical spinal unit (C3-C4) was distracted with a porous metal interbody fusion device (IFD) and stabilized with a polyaxial pedicle screw and rod construct. Neurologic examinations were performed preoperatively and postoperatively. Radiographs of the fusion site and adjoining vertebrae were obtained preoperatively and monthly. Horses were euthanized at 8 months and spinal units were evaluated for osseointegration and implant safety via micro-computed tomography (CT), histology, and histomorphometry. RESULTS: The procedure was performed safely in all horses, without severe postoperative complications. Evaluation of radiographs revealed no implant failure, implant migration, or spinal unit instability in any of the horses. The presence of new bone formation around the screw and rod constructs was confirmed via micro-CT. No evidence of inflammation or iatrogenic damage was noted from histology. New bone was present within the IFD in all horses, with variable osseointegration on the cranial and caudal surfaces of the implant in 3 horses. CONCLUSION: The novel technique reported in the present study was safely applied to stabilize the C3-C4 spinal unit in the horses tested here and led to variable osseointegration within 8 months. CLINICAL SIGNIFICANCE: The results of this study justify evaluation of this technique in horses with a diagnosis of cervical vertebral compressive myelopathy.

Comparison of 3 suture closure techniques for pelvic flexure enterotomy in equine cadaveric large colon.

OBJECTIVE: To compare a 2-layer closure with suture line reversal for a pelvic flexure enterotomy to 1-layer and traditional 2-layer hand sewn closures. STUDY DESIGN: Ex vivo, simple randomized study. SAMPLE POPULATION: Large colon segments from adult horses (n = 18). METHODS: Pelvic flexures were harvested from 18 horses and randomly assigned to 1 of 3 closure techniques (n = 6 per technique). A 10-cm enterotomy was made in each pelvic flexure and closed with the assigned technique. Closure time, luminal diameter via contrast radiographs, and bursting pressure were recorded for each specimen and compared between techniques using 1-way ANOVA with Duncan post hoc test at P < .05. RESULTS: There was a significant difference in closure time (P = .034) with 1-layer closure faster than both the traditional 2-layer closure (P=.024) and the 2-layer closure with suture line reversal (P = .030). There was no significant difference in luminal diameter or bursting pressure between the 3 closure techniques. CONCLUSIONS: Two-layer closure with suture line reversal may be an alternative to traditional 2-layer closure for closure of the pelvic flexure based on ex vivo bursting pressure testing and closure time. A 1-layer simple continuous closure resisted bursting pressure not different to both 2-layer closure techniques. Further in vivo evaluation may be indicated.

Laparoscopic Evaluation of the Reproductive Tract in Two Female Polar Bears (Three Procedures) (Ursus maritimus).

Polar bears (Ursus maritimus) face a number of challenges that threaten the survival of the species. Captive breeding represents one essential facet of species conservation, but aspects of the polar bear's reproductive physiology, such as follicle maturation, coitus-induced ovulation, and pseudopregnancy, are poorly characterized and present challenges for enhancing natural reproductive success and the application of advanced reproductive techniques. Due to the absence of a reliable transrectal or transabdominal ultrasound method for ovarian examination in the species, the ovaries of two adult female polar bears were examined laparoscopically to evaluate the feasibility of surgical access to the ovaries, oviduct, and uterus. The minimally invasive procedure was easily and rapidly performed in both bears and all procedures. Direct visual assessment of the ovary was possible after dissection of a fatty bursal sac, which completely enclosed the ovaries. In the second bear, laparoscopic manipulation of the ovary to draw it closer to the body wall enabled transcutaneous ultrasound. Laparoscopy may be a valuable tool to aid in the application of advanced reproductive technologies in polar bears.

Outcomes after cervical vertebral interbody fusion using an interbody fusion device and polyaxial pedicle screw and rod construct in 10 horses (2015-2019).

BACKGROUND: Further development of surgical techniques for equine cervical stabilisation is necessary to make the procedure less technically demanding, reduce complications and improve outcomes. OBJECTIVE: To describe clinical outcomes and owner reports in horses undergoing placement of an interbody fusion device and polyaxial pedicle screw and rod construct for cervical vertebral fusion in horses with cervical vertebral compressive myelopathy. STUDY DESIGN: Retrospective case series. METHODS: Data were retrieved from medical records of 10 horses undergoing cervical vertebral fusion (2015-2019). Records were evaluated for signalment, duration of clinical signs, number and location of compression sites, grade of ataxia, duration of hospitalisation and complications. Long-term follow-up was obtained through clinical re-evaluation, postoperative radiographs and owner contact. RESULTS: Breeds were mixed. Median age was 24 (range 12-168) months. There were 2/10 mares, 4/10 geldings and 4/10 stallions. Preoperative grade of ataxia ranged from 1-3/5. Fusion was performed at one (n = 3) or two (n = 7) sites. Two horses were euthanised within the first year. In 6 of 8 horses with ≥1-year follow-up, ataxia improved by 1-3 grades, with an average improvement of 1.25 grades. In four horses, ataxia improved to grade 0-1. In two horses the gait was unaffected, but neck comfort improved. Complications included seroma formation (n = 9), pain (n = 5), fever (n = 4), upper respiratory tract obstruction (n = 2), azotemia (n = 2), screw breakage (n = 2), progression of neurological signs (n = 1), Horner's Syndrome (n = 1), dysphagia (n = 1), hives (n = 1), implant infection (n = 1) and nondisplaced fracture (n = 1). MAIN LIMITATIONS: Small case series, heterogeneous patient population. CONCLUSIONS: This technique resulted in ≥1 grade gait improvement in 6/10 cases operated and 6/8 cases for which ≥1-year follow-up was available, similar to other methods. Fatal complications related to implant placement did not occur. This technique may represent a safer alternative to current techniques of ventral interbody fusion with similar outcomes.

Allogeneic mesenchymal stromal cells for cartilage regeneration: A review of in vitro evaluation, clinical experience, and translational opportunities.

The paracrine signaling, immunogenic properties and possible applications of mesenchymal stromal cells (MSCs) for cartilage tissue engineering and regenerative medicine therapies have been investigated through numerous in vitro, animal model and clinical studies. The emerging knowledge largely supports the concept of MSCs as signaling and modulatory cells, exerting their influence through trophic and immune mediation rather than as a cell replacement therapy. The virtues of allogeneic cells as a ready-to-use product with well-defined characteristics of cell surface marker expression, proliferative ability, and differentiation capacity are well established. With clinical applications in mind, a greater focus on allogeneic cell sources is evident, and this review summarizes the latest published and upcoming clinical trials focused on cartilage regeneration adopting allogeneic and autologous cell sources. Moreover, we review the current understanding of immune modulatory mechanisms and the role of trophic factors in articular chondrocyte-MSC interactions that offer feasible targets for evaluating MSC activity in vivo within the intra-articular environment. Furthermore, bringing labeling and tracking techniques to the clinical setting, while inherently challenging, will be extremely informative as clinicians and researchers seek to bolster the case for the safety and efficacy of allogeneic MSCs. We therefore review multiple promising approaches for cell tracking and labeling, including both chimerism studies and imaging-based techniques, that have been widely explored in vitro and in animal models. Understanding the distribution and persistence of transplanted MSCs is necessary to fully realize their potential in cartilage regeneration techniques and tissue engineering applications.

Usefulness of caudomedial-craniolateral oblique radiographic views for the diagnosis of injury to the origin of the cranial cruciate ligament in two horses.

CASE DESCRIPTION A 12-year-old mixed-breed mare (horse 1) and 6-year-old Friesian gelding (horse 2) were examined for chronic lameness associated with the stifle joint. CLINICAL FINDINGS Lameness examination revealed effusion of the right (horse 1) or left (horse 2) femoropatellar and medial femorotibial joints and grade 3/5 (horse 1) or 4/5 (horse 2) lameness. A diagnosis of cranial cruciate ligament (CCL) injury with associated mineralization and avulsion (horse 1) or mineralization alone (horse 2) was facilitated in both horses with a caudomedial-craniolateral oblique radiographic view obtained 45° medial to the caudocranial line, which highlighted the origin of the ligament on the caudoaxial aspect of the lateral femoral condyle within the intercondylar fossa. These lesions were subsequently confirmed via CT. TREATMENT AND OUTCOME Arthroscopy of the medial and lateral femorotibial joints was performed for horse 1 and revealed the osseous fragment associated with the CCL, but the fragment could not be removed. Horse 2 was euthanized while anesthetized following CT owing to the poor prognosis. CONCLUSIONS AND CLINICAL RELEVANCE Radiography is typically the first imaging modality attempted for horses with CCL injury, particularly outside the hospital setting. A 45° caudomedial-craniolateral oblique radiographic view may aid in diagnosis of CCL injury when avulsion or mineralization is present. Although this view is not commonly included in the typical radiographic series for imaging of the stifle joint in horses, it should be considered when CCL injury is suspected.