Background Investigation of image quality in clinical equine magnetic resonance (MR) imaging may optimise diagnostic value. Objectives To assess the influence of field strength and anaesthesia on image quality in MR imaging of the equine foot in a clinical context. Study design Analytical clinical study. Methods Fifteen equine foot studies (five studies per system) were randomly selected from the clinical databases of three MR imaging systems: low‐field standing (LF St), low‐field anaesthetised (LF GA) and high‐field anaesthetised (HF GA). Ten experienced observers graded image quality for entire studies and seven clinically important anatomical structures within the foot (briefly, grade 1: textbook quality, grade 2: high diagnostic quality, grade 3: satisfactory diagnostic quality, grade 4: non‐diagnostic). Statistical analysis assessed the effect of anaesthesia and field strength using a combination of the Pearson chi‐square test or Fisher’s exact test and Mann‐Whitney test. Results There was no difference in the proportion of entire studies of diagnostic quality between LF St (90%, 95% CI 78%‐97%) and LF GA (88%, 76‐95%, P = .7). No differences were evident in the proportion of diagnostic studies or median image quality gradings between LF St and LF GA when assessing individual anatomical structures (both groups all median grades = 3). There was a statistically significant difference in the proportion of entire studies of diagnostic quality between LF GA and HF GA (100%, 95% CI lower bound 94%, P = .03). There were statistically significant differences in median image quality gradings between LF GA (all median grades = 3) and HF GA (median grades = 1 (5/7 structures) or 2 (2/7 structures) for all individual anatomical structures (all P < .001). The reasons reported for reduced image quality differed between systems. Main limitations Randomised selection of cases from clinical databases. Individual observer preferences may influence image quality assessment. Conclusions Field strength is a more important influencer of image quality than anaesthesia for magnetic resonance imaging of the equine foot in clinical patients.

SummaryAn 18‐year‐old Warmblood gelding was presented for investigation of a large, firm mass over the medial and plantar aspect of the left distal metatarsal and fetlock region. The mass was first identified 4 months prior to referral, following a traumatic incident, and had over time gradually increased in size. Clinical examination and diagnostic imaging revealed a large soft tissue mass adjacent to the metatarsophalangeal joint and digital flexor tendon sheath, with no overt involvement of underlying bone. The mass was surgically excised under general anaesthesia using a harmonic scalpel with limited margins to avoid compromise of adjacent anatomical structures. Following histology, the mass was diagnosed as a fibrosarcoma. Twelve months after surgical resection, no signs of recurrence were evident. This report demonstrates that fibrosarcoma of the equine distal limb may be successfully managed with surgical excision. The use of a harmonic scalpel should be considered as an alternative to sharp excision when treating fibrosarcoma or other infiltrative tumours, particularly those located in regions where only limited surgical margins may be achieved.

Summary Background Synovial sepsis of unknown origin is a rare cause of lameness in the adult horse, and a haematogenous pathogenesis has been proposed in previous cases. Objectives To describe the features and outcome of synovial sepsis of unknown origin in adult Thoroughbred racehorses. Study design Retrospective case series. Methods Hospital records for admissions between 2005 and 2015 were reviewed to identify adult horses diagnosed with synovial sepsis of unknown origin. Presentation, clinicopathological, microbiological and diagnostic imaging findings were recorded. Treatment methods, surgical findings, complications and long‐term outcome were evaluated. Results Eleven cases were identified over the study period. Diagnosis was established from clinical examination and clinicopathologic findings, which were comparable to other aetiologies of synovial sepsis. Affected structures included synovial joints, tendon sheaths and bursae. Concurrent osteochondritis dissecans or articular cartilage lesions were evident during arthroscopic surgery in three cases. Significant intrasynovial haemorrhage was not identified. Microbial culture of synovial fluid or synovial biopsy was positive in 6/11 of cases, with all isolates being Gram‐positive cocci. Of the 6 positive microbial cultures, all isolates demonstrated in vitro sensitivity to a cephalosporin antimicrobial agent. A concurrent remote wound was present in a single case. No other potential origins of bacteraemia were identified. Treatment methods included endoscopic surgery, standing multineedle lavage, intravenous regional limb perfusion, intrasynovial medication and/or systemic antimicrobial administration. All horses survived to hospital discharge. For the 6/11 cases that raced following synovial sepsis, the median period for return to racing was 221 days. Main limitations A small study population, which was retrospectively reviewed. Conclusions Synovial sepsis of unknown origin is rare in the adult Thoroughbred racehorse and can affect a range of synovial structures. A concurrent potential source of bacteraemia is rarely identified. With appropriate management, the prognosis to return to racing is fair.

Summary Respiratory distress due to acute upper respiratory tract obstruction is an uncommon emergency in equine practice. However, clinicians should be confident with the approach to this truly life‐threatening scenario. Clinical signs are obvious at rest and include increased respiratory effort, loud respiratory noise and recumbency as asphyxiation progresses. Many cases of upper respiratory tract obstruction involve the pharynx or larynx, though obstruction in other regions of the upper respiratory tract and other causes of respiratory distress should be considered. Generally, the obstruction can be bypassed by placing a nasotracheal tube under endoscopic guidance or by making a temporary tracheotomy to ensure a patent airway. Following this stabilisation, further investigation into the cause of airway obstruction can be performed. Endoscopy is usually the most valuable diagnostic tool, though other imaging modalities can be useful. Further empirical treatment is often required, though the specific management will vary depending on the pathology present.

Objective: To document variations in the application of equine prosthetic laryngoplasty among equine surgeons.Study design: Cross-sectional survey. Sample population: Six hundred and seventy-eight equine surgeons performing prosthetic laryngoplasty. Methods: An online questionnaire was sent to equine surgeons, including diplomates of the American College of Veterinary Surgeons and European College of Veterinary Surgeons. Questions focused on participant profile, surgical technique, antimicrobial therapy, and concurrent procedures. Descriptive statistical analysis was performed on the survey output. Results: Complete responses were received from 128/678 individuals, mostly from experienced surgeons. Most participants used 2 prostheses (106/128, 82.8%) and a single loop was the most common method used to anchor the prosthesis in the cricoid (95/128, 74.2%) and arytenoid (125/128, 97.7%) cartilages. Use of general anesthesia was common, although 46/128 (35.9%) participants now performed most laryngoplasty surgery with standing sedation. The material used as a prosthesis varied among surgeons, although participants typically aimed to achieve grade 2 intraoperative arytenoid abduction. Participants most commonly administered perioperative systemic antimicrobial therapy for 1-3 days (57/128, 44.5%) and 48/128 (37.5%) used local antimicrobial therapy. Conclusion: Most surgeons performed laryngoplasty with 2 prostheses, a single loop construct at the muscular process of the arytenoid cartilage and systemic antimicrobial therapy. There was variation in the preferred method of surgical restraint, prosthesis material selection, and use of local antimicrobial therapy.

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Regulation of cytosolic pH is vital for normal cellular function. Pathological microenvironments are associated with acid loading and cell metabolic processes generate acid equivalents. Cells have therefore evolved several mechanisms for proton extrusion, including plasmalemmal H+ATPase (active. when cells are acid loaded) and the Na/H+ antiporter (which in HPBMs is activated during formylmethionyl-leucyl phenylalanine induces acidosis. We have shown that inhibition of H+ATPase is associated with a mild intracellular acidosis (approx. 00.2-0.3 pH unit below physiological pH) in HAMs and that this is associated with reduced Fc mediated phagocytosis. The aim of these experiments was to assess the role of H+ATPase in HPBM pH regulation and phagocytosis and assess its role in the generation of intracellular reactive oxygen species (a vital cytotoxic mechanism) in HAMs and HPBM. PH changes were monitored flow cytometrically using pH sensitive intracellular probes. Respiratory burst was assessed by the reduction of dihydrorhodamine. Fc mediated phagocytosis was assessed flow cytometrically following exposure to Fc opsonised FITC labelled E.Coli HPBMs failed to recover physiological pH following acid loading in the presence of a specific H+ATPase inhibitor bafilomycin A 1 (0.002 pH units/min(baf) vs 0.21 pH units/min, p<0.05), but recovery was insensitive to the antiporter inhibitor amiloride. Bafilomycin reduced Fc mediated phagocytosis (mean channel fluorescence (mcf) vs 465, p<0.005. Respiratory burst was reduced in HAMs (mcf 379 vs 480, p<0.05) and in HPBMs (224 vs 302, p<0.05). These results suggest a critical role for H+ATPases in regulation of cytosolic pH and effector function of these cells.

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