Giselle Hosgood

Objective
To determine the effect of plate–bone distance and screw number on 2.0-mm locking compression plate (LCP) torsional stiffness and plate strain for a fixed working length in a diaphyseal fracture gap model.


Study Design
In vitro biomechanical study.


Methods
The LCP was tested with nine different combinations of plate–bone distance (PBD) (1, 1.5, and 3 mm) and screw number (SN) (two, three, or four screws per fragment) across the same working length. Six replicates per group were tested. Constructs were subjected to quasi-static, non-destructive torsion producing overall construct stiffness data (Nm/degree). Plate surface strain data were recorded from three-dimensional digital image correlation during testing for all constructs.


Results
A greater PBD and a low SN resulted in lower construct stiffness (p = 0.015, and P > 0.0001, respectively) in torsion. Across all PBD, there was significantly less stiffness for constructs with two screws per fragment, compared with three screws or four screws. No significant difference was detected in plate strain for any combination of PBD and SN.


Conclusion
In this model, incrementally increasing the PBD and decreasing the SN resulted in less construct stiffness in torsion, with marked reduction in torsional stiffness in constructs with two screws per fragment compared with three or four screws per fragment.

Background
Reliable assessment of foot conformation is essential for podiatric management in Miniature Horses and Ponies, yet reference ranges and the reliability of radiographic measurements remain poorly defined.

Aims/objectives
This study quantified radiographic measurements of foot conformation in sound, skeletally mature Miniature Horses and Ponies and evaluated their agreement, reliability, and precision.

Methods
Standardised lateromedial and dorsopalmar/plantarodorsal radiographs were obtained from 30 Miniature Horses and Ponies. Two observers took 60 measurements from 10 sets of projections on three occasions. Reliability and precision were quantified using intraclass correlation coefficients (ICC) and within-subject coefficients of variation (CV), and agreement was assessed against ±5 % limits of agreement (LOA). These measurements were then obtained by a single observer from 30 horses. The median and 95 % confidence intervals (CI) of each measurement were calculated.

Results
Most linear and angular measurements had moderate to excellent reliability (median ICC 0.86, interquartile range [IQR] 0.22) and precision (median CV 4 %, IQR 7 %) but exceeded ±5 % LOA. Hoof wall thickness ratios had good reliability (minimum ICC 0.69, 95 % CI 0.49–0.96), excellent precision (maximum CV 9 %, 95 % CI 2–11 %), and acceptable agreement (maximum LOA ±4.7 %, 95 % CI −0.11–0.09). Marginal means (95 %CIs) were: dorsal, forefeet 0.245 (0.237–0.253), hindfeet 0.240 (0.232–0.248); lateral, forefeet 0.186 (0.180–0.194), hindfeet 0.180 (0.173–0.186); medial, pre-trim 0.177 (0.171–0.183), post-trim 0.169 (0.163-0.175).

Conclusion
Hoof wall ratios provide consistent, repeatable radiographic measurements suitable for clinical use in skeletally mature Miniature Horses and Ponies, supporting objective laminitis screening and monitoring.

The consequences of large-volume hepatectomy on the remaining liver in the dog are not documented. This case report documents a progressive hepatopathy after central division hepatectomy in a 10-year-old female Lhasa Apso dog. Serum biochemistry at presentation for chronic urinary incontinence indicated a hepatopathy, with a liver mass identified on subsequent ultrasound. Referral for computed tomography (CT) (day 76) demonstrated a central division liver mass (~204cm
). A central division hepatectomy (right medial and quadrate lobes; gallbladder) was performed, with microscopic examination confirming a hepatocellular carcinoma. Serial biochemistry over a three-and-a-half-year follow-up documented progressive hepatopathy. Serial CT hepatic volumetry (day 76, 136, 1041) documented gross enlargement of the residual right lateral liver lobe and gross reduction of the residual left medial and lateral liver lobes. Biopsies of the left and right liver (day 187) demonstrated disparate pathology with microscopic features consistent with regeneration in the right liver and elevated portal vein pressure (PVP) in the left liver. This report documents progressive hepatopathy evidenced by serum biochemistry, disparate and persistent gross liver changes on posthepatectomy CT, and microscopic changes consistent with elevated PVP. Findings from this case demonstrate similarities to posthepatectomy liver failure (PHLF) and small-for-size-and-flow syndrome (SFSS) as reported in people and animal models. The progressive hepatopathy posthepatectomy in this case prompts consideration and further investigation for the development of PHLF and SFSS in the dog.

This report is the first to document chylothorax after patent ductus arteriosus (PDA) ligation in a dog with a persistent left cranial vena cava (PLCVC), highlighting potential complications arising from concurrent cardiovascular anomalies. A nine-month-old female desexed Pomeranian was referred for PDA. Echocardiography confirmed a left-to-right shunt with mild left-sided cardiac changes from volume overload. At left fourth intercostal thoracotomy, an aberrant vein (5 mm) coursing over the PDA within the mediastinum was retracted proximally to facilitate PDA ligation. Retraction was released before thoracotomy closure, and the vein remained grossly unaltered. The dog represented 3 days postoperative for dyspnoea and had bilateral chylous pleural effusion. Thoracic computed tomography with intravenous contrast identified a complete PLCVC, which was continuous with the left brachiocephalic vein and inserted into the right atrium without any venous connection to the normal right cranial vena cava. A thoracostomy tube was placed, and the chylothorax resolved spontaneously. Repeat echocardiogram eight weeks postoperative showed normal laminar trans-pulmonic flow and reversal of cardiac changes. It is hypothesised that an acute increase in hydrostatic venous pressure from transient obstruction of the PLCVC during intraoperative retraction impeded thoracic duct emptying into the venous system. This in turn may have caused chyle leakage through afferent lymphatics with chylothorax. It is unlikely PLCVC thrombosis was a cause given chylothorax was transient and the PLCVC was normal on computed tomography (CT); nor iatrogenic thoracic duct damage given the surgical approach was left-sided and the duct courses through the right.

Objective
To document the prevalence and incidence rate of infection in dogs undergoing partial tarsal arthrodesis (PTA). For context, findings were compared with the prevalence of infection following tibial plateau leveling osteotomy (TPLO) at the same institution. Independent variables associated with infection were also identified.

Study design
Case–control study.

Animals
Eighty-nine dogs underwent PTA; 292 dogs underwent TPLO.

Methods
Medical records for dogs that underwent PTA from 2017 to 2023 and dogs that underwent TPLO between January 2022 and December 2022 were reviewed. The prevalence, incidence rate, odds and incidence rate ratio of infection were calculated.

Results
The prevalence of infection following PTA was 43%; following TPLO it was 13%. The incidence rate of infection was 0.00276 (95% CI: 0.00198–0.00375) and 0.00010 (95% CI: 0.00007–0.00013) infections per dog-week, respectively. The odds ratio and incidence rate ratio for infection following PTA were 5.0 (95% CI: 3.1–9.0) and 28.2 (95% CI: 17.7–45.0), respectively.

Conclusion
The prevalence and incidence rate of infection were higher following PTA than TPLO. Dogs that underwent PTA were five times more likely to develop infection than dogs that underwent TPLO, and developed infection at 28 times the rate of dogs that underwent TPLO. Dogs with open wounds, no postoperative bandage, and treated with a combined medial and lateral approach, had a higher point prevalence of infection.

Objective:
To explore changes in urinary biomarkers of acute kidney injury (AKI) in healthy dogs experiencing intra-operative hypotension and explore the relationship between blood pressure and urinary biomarkers.

Study Design:
Observational cohort study.

Animals:
A group of 50 client owned dogs.

Methods:
Urine and blood samples were collected prior to anaesthesia (T0), within 24 hours after anaesthesia (T1) and 10 days post-surgery (T10). During anaesthesia, the lowest mean arterial pressure (MAP) in each dog. Impact of duration was explored by categorising according to arbitrary thresholds of MAP < 50, < 60, < 70 and < 80 mmHg and calculating duration (minutes) within each category Serum creatinine (Cr) and validated biomarkers of AKI including urinary gamma-glutamyl transferase (uGGT), urinary neutrophil gelatinase-associated lipocalin (uNGAL), and urinary cystatin C (uCystatin C) were measured. Biomarker measurements were standardised to urinary Cr. The frequency of dogs with proportional increases between T1 and T0 and between T10 and T0 was recorded. Multiple regression analysis was performed to determine the simplest subset of independent variables (lowest MAP, duration with each MAP category) to best explain the variance in the proportional change of each biomarker.

Results:
Hypotension, defined as MAP < 60 mmHg was observed in 38/50 (76 %) of the dogs. Between T1 and T0, increases in uGGT/Cr, uCystatin C/Cr, and uNGAL/Cr were observed in 37 (82%), 17 (41 %) and 19 (35%) of 50 dogs, respectively. Of the variance observed in uGGT/Cr at T1/T0, 62% could be explained by the lowest MAP recorded when combined with duration MAP < 50mmHg (adjusted R2 0.62).

Conclusion and clinical relevance:
In this clinical model of intra-operative hypotension uGGT/Cr demonstrated potential for diagnosis of early AKI in healthy dogs. Increases in validated biomarkers uCystatin C/Cr, and uNGAL/Cr support their use in future studies investigating different causes or severity of AKI.

Introduction
Atelectasis is a common occurrence during anesthesia, and positive end-expiratory pressure (PEEP) ventilation and recruitment maneuvers (RM) can be used to mitigate this. However, both techniques may be associated with side effects in healthy lungs, and close monitoring is indicated. This study aimed to evaluate the effects of PEEP and RM in healthy dogs and to compare functional lung monitoring methods by electrical impedance tomography (EIT), volumetric capnography (VCap), and blood gas analysis with the gold-standard anatomical monitoring provided by computed tomography (CT).

Methods and materials
Nine healthy Beagle dogs underwent anesthesia and mechanical ventilation three times. After 35 min using zero end-expiratory pressure (ZEEP), CT images, VCap, EIT measurements, and arterial blood gas samples were taken. Thereafter, either (1) ZEEP was continued, (2) PEEP initiated or (3) an RM was performed followed by PEEP. Ten minutes after changing the ventilation mode all measurements were repeated. Only one ventilation mode was employed during each anesthesia.

Results
During RM, we found a significant increase in the percentage of overaerated lung (Vhyper) (p < 0.001), while the amount of normally aerated lung (Vnormal), poorly aerated lung and non-aerated lung decreased (p ≤ 0.001). VCap showed an increase in airway dead space (VDaw/VT) (p = 0.002), and a decrease in alveolar dead space (VDalv/VTalv). For PEEP, an increase in airway dead space (p = 0.003) was found. For both groups, the amount of carbon dioxide exhaled per breath (VTCO2,br) decreased (p = 0.001), and EIT showed a shift of the center of ventilation to the dependent lung areas (p = 0.021 and p = 0.046, respectively). Oxygenation was superior in RM compared to ZEEP (p = 0.033). The arterial partial pressure of carbon dioxide decreased in RM (p = 0.012). Positive associations were found between Vhyper and VDaw/VT (p = 0.004), Vhyper and VDaw/VT (p = 0.004), Vhyper and Vnormal with VTCO2,br (p = 0.002 for both). Negative associations were found between Vhyper and VDalv/VTalv (p = 0.004) and non-dependent silent spaces (p = 0.050), and Vnormal with oxygenation (p = 0.030).

Conclusion
While RM may be effective in improving gas exchange, it appears to be not benign in healthy lungs, and PEEP might be the preferable strategy to avoid lung collapse during anesthesia. Functional monitoring – EIT, VCap, blood gas analysis – does not detect changes corresponding to anatomical findings on CT.

Objective: Data from two-plane electrical impedance tomography (EIT) can be reconstructed into various slices of functional lung images, allowing for more complete visualisation and assessment of lung physiology in health and disease. The aim of this study was to confirm the ability of 3d EIT to visualise normal lung anatomy and physiology at rest and during increased ventilation (represented by rebreathing).

Approach: Two-plane EIT data, using two electrode planes 20cm apart, were collected in 20 standing sedate horses at baseline (resting) conditions, and during rebreathing. EIT data were reconstructed into 3d EIT whereby tidal impedance variation (TIV), ventilated area, and right-left and ventral-dorsal centres of ventilation (CoVRL and CoVVD, respectively) were calculated in cranial, middle and caudal slices of lung, from data collected using the two planes of electrodes.

Main results: There was a significant interaction of time and slice for TIV (p < 0.0001) with TIV increasing during rebreathing in both caudal and middle slices. The ratio of right to left ventilated area was higher in the cranial slice, in comparison to the caudal slice (p = 0.0002). There were significant effects of time and slice on CoVVD whereby the cranial slice was more ventrally distributed than the caudal slice (p < 0.0009 for the interaction).

Significance: The distribution of ventilation in the three slices corresponds with topographical anatomy of the equine lung. This study confirms that 3d EIT can accurately represent lung anatomy and changes in ventilation distribution during rebreathing in standing sedate horses.

Objective: To describe a modified closed sacculectomy technique for non‐neoplastic anal sac disease in dogs, and to describe the management and short‐term outcomes in dogs undergoing sacculectomy by the described technique.

Study design: Retrospective case series. Sample population A total of 50 dogs.

Methods: Electronic medical records were reviewed to identify dogs undergoing bilateral anal sacculectomy for non‐neoplastic anal sac disease using the described closed technique between January 1, 2013 and February 1, 2024.

Results: A total of 50 dogs underwent bilateral anal sacculectomy for non‐neoplastic anal sac disease. Intraoperative anal sac perforation was reported in five dogs (10%). A total of 43 dogs were available for two‐week follow‐up. Grade 1 complications were reported in 14/43 dogs (32%), grade 2 complications in 2/43 dogs (5%), and grade 3B in 2/43 dogs (5%). At two‐weeks postoperatively, 13/14 dogs (93%) had resolution of grade 1 complications. Both dogs with grade 2 complications had resolution reported at two weeks postoperatively, and both dogs with grade 3B complications had resolution reported at two weeks following revision surgery.

Conclusion: Intraoperative complications consisted of anal sac perforation without further complication. Minor postoperative complications were mostly self‐limiting, supporting previous literature. Major complications were infrequent and resolved following single revision surgery.

Clinical significance: The technique reported provides an alternative to excise intact and non‐neoplastic anal sacs in dogs. The key features of this technique are immediate anal sac identification by following the anatomic path of the duct, minimal peri‐saccular dissection, no requirement for packing of the anal sac, and complete removal of the duct and anal sac.

The abstract sentence “strain was significantly, incrementally, higher as working length was extended” remains true. Strain was higher in the long working length (LWL) constructs than the short (SWL) and medium working length (MWL) constructs. Higher measured strain at a longer working length in our study can be described as a direct relationship. We specifically used the term incremental in our results to highlight that we have measured at three distinct working lengths and have not made inferences about strain assessment between these measured working lengths...