Equine Veterinary Journal最新文献

Background: Strangulating lipoma obstruction (SLO) is the most common cause of equine small intestinal strangulation and is fatal without surgery. Currently, epidemiological information is primarily limited to signalment-related risk factors and requires further investigation.

Objectives: To identify horse-level risk factors for SLO and/or abdominal lipoma(s) (LP) formation in horses with acute colic that underwent surgery or post-mortem examination at participating equine clinics.

Study design: Prospective, international, multicentre, epidemiological study.

Methods: An epidemiological study was conducted over 27 months (January 2022-April 2024) in 8 clinics (UK n = 4, USA n = 4) to identify variables associated with altered likelihood of SLO and/or LP. Horses presenting with acute colic signs that underwent surgery or post-mortem examination were eligible. Those (i) that had SLO as the primary cause of colic, or (ii) those that had mesenteric and/or omental lipoma(ta) (LP) were compared to horses without lipomata. Signalment, adiposity, endocrine status, and lipomata deposition data were analysed using univariable and multivariable logistic regression models.

Results: Data from 392 horses was obtained (108 SLO; 190 LP). Increasing age (odds ratio [OR] 1.23) for every year increase in age 95% CI (95% CI: 1.17-1.30, p < 0.001), male sex (OR 1.78, 95% CI: 1.08-2.95, p = 0.02) and clinical indicators of Equine Metabolic Syndrome (EMS) (OR 4.77, 95% CI: 2.93-7.77, p < 0.001) were significantly associated with increased likelihood of SLO. Increasing age, clinical indicators of EMS, indicators of previous/current laminitis (hoof growth ring score), jejunal mesenteric fat score and omental fat scores were significantly associated with increased likelihood of LP.

Main limitations: Population restricted to horses with acute colic signs admitted to collaborating clinics.

Conclusions: Measures to prevent adiposity and EMS development appear important to reduce the likelihood of LP and SLO. Further investigation of differential adipose tissue deposition between male and female horses is warranted.

Background: The healthcare sector contributes significantly to global greenhouse gas (GHG) emissions, with anaesthetic gases being a notable contributor. Implementing sustainable practices in equine anaesthesia, such as low-flow anaesthesia, offers potential benefits.

Objectives: To audit oxygen and isoflurane usage in five equine hospitals, their associated GHG emissions, and the impact of anaesthesia training on mitigating these emissions.

Study design: Multi-centre clinical audit.

Methods: This audit covered two periods: study period one (1 June-30 September 2022) and study period two (1 June-30 September 2023). After period one, an anaesthesia training programme introduced low-flow techniques. Data collected retrospectively included patient signalment, anaesthetic protocol, and 5-min recordings of fresh gas flow (FGF) and vapouriser settings. GHG emissions (in carbon dioxide equivalents) and costs (in £) were calculated. Statistical analysis used a linear mixed-effects model with a significance level of p-value <0.05.

Results: A total of 414 general anaesthetics were audited. Between study period one and two, isoflurane and oxygen usage decreased by 9.6% and 17.9%, respectively, resulting in a 9.6% reduction in GHG emissions (from 14.6 to 13.2 tCO₂e). A linear mixed-effects model identified five significant predictors of GHG emissions per case: study period, oxygen usage, anaesthesia duration, average isoflurane vapouriser setting, and the interaction between oxygen usage and study period. Cases in study period two were associated with lower GHG emissions, producing on average 10.4 kgCO₂e less per case (p = 0.01), while each additional litre of oxygen consumed increased emissions by 0.12 kgCO₂e (p < 0.001).

Main limitations: Missing data from FGF and/or vapouriser settings and the minimal variability between hospitals could be perceived as limitations.

Conclusions: This audit demonstrates that practising low-flow anaesthesia can effectively reduce the environmental impact of inhalant anaesthetic agents during equine anaesthesia. Wider adoption could improve sustainability, although further research and broader professional engagement are needed.

Background: Post-anaesthetic colic (PAC) is a complication in horses undergoing general anaesthesia (GA). Various preoperative feeding strategies are used in equine practice, yet their impact on PAC remains unclear.

Objectives: To identify perioperative risk factors associated with PAC and evaluate the influence of preoperative fasting on PAC prevalence and faecal output.

Study design: Retrospective cohort study.

Methods: Medical records of horses undergoing non-abdominal surgery under GA were reviewed. Horses were categorised into fasted and non-fasted groups based on their pre-anaesthetic feeding regimen. Multivariable logistic regression was used to identify variables associated with PAC. Differences in faecal output and water intake between groups were analysed using a two-tailed hypothesis test.

Results: A total of 620 cases were included. Fasting (odds ratio [OR] 2.7, 95% CI 1.4-5.5, p = 0.005), increased surgery duration (per minute) (OR 1.01, 95% CI 1.002-1.02, p = 0.017) and increasing age (OR 1.08, 95% CI 1.02-1.15, p = 0.012) were significantly associated with PAC. Non-fasted horses passed significantly more manure post-operatively. Median (IQR) manure production per hour was 0.44 (0.31-0.61) piles in non-fasted versus 0.38 (0.25-0.50) piles in fasted horses during the first 24 h post-anaesthesia (p < 0.001) and 0.53 (0.42-0.67) versus 0.50 (0.36-0.63) in the second 24 h post-anaesthesia (p = 0.04). Water intake 12 h pre-anaesthesia was also higher in non-fasted horses (1.02 [0.73-1.75] L/h) compared to fasted horses (0.88 [0.53-1.75] L/h; p < 0.001).

Main limitations: Poor overall accuracy of the predictive model obtained. The retrospective design of the study may introduce bias due to possible inconsistencies in medical records.

Conclusion: Pre-operative fasting was associated with increased risk of PAC and reduced faecal output in horses. These findings support reconsidering fasting practices in equine anaesthesia.

Background: Significant distal interphalangeal joint (DIPJ) pathology, particularly affecting soft tissue and articular cartilage, is often not identifiable on radiographs but can be accompanied by joint capsule enthesopathy on the middle phalanx (P2), which can be readily identified.

Objectives: To explore frequency and correlations between DIPJ capsule enthesopathy identified on magnetic resonance imaging (MRI) and radiographs and DIPJ articular cartilage abnormalities and other concurrent soft tissue or osseous pathology within the foot found on MRI.

Study design: Retrospective descriptive case series.

Methods: Cases identified with DIPJ capsule enthesopathy on MRI and radiographs were retrospectively reviewed. Abnormalities were graded using a 4-point scale. Descriptive statistics and Spearman's rank correlations were used to analyse the relationship between the presence and grade of DIPJ capsule enthesopathy, lameness, and DIPJ intra-articular and collateral ligament abnormalities seen on MRI.

Results: MRI and radiographic studies of 21 feet with DIPJ capsule enthesopathy were analysed. DIPJ articular cartilage lesions were identified in 20/21 limbs (95%). There was no significant correlation between the degree of DIPJ capsule enthesopathy and the severity of articular cartilage lesions. DIPJ proliferative synovitis and osteophytes were present in the majority of limbs (91% and 95%), respectively. DIPJ collateral ligaments were abnormal in 52% of the limbs. With MRI-based assessment, DIPJ capsule enthesopathy grade was moderately positively correlated with DIPJ collateral ligaments' findings severity (r = 0.53, p = 0.01).

Main limitations: Retrospective character, no histopathology, studied cases limited to one referral centre, low case numbers and statistical power.

Conclusions: The presence of DIPJ capsule enthesopathy on radiographs is a reliable finding to rule in DIPJ damage and support further case management, particularly in cases where advanced imaging is unavailable or desired.

Background: Proximal sesamoid bone fractures (PSBFs) are a leading cause of economic losses. Post-operative racing prognosis is multi-factorial; however, recent studies are lacking.

Objectives: To provide an update on racing outcomes for horses undergoing surgical management of PSBFs, analyse variables affecting performance and compare post-operative racing performance with pre-operative data and case-matched controls.

Study design: Retrospective case series.

Methods: Thoroughbred racehorses that underwent PSBF repair (2008-2022) were included. Data retrieved included fracture type, limb, axiality, treatment, age, sex, suspensory ligament branch (SLB) injury, surgical date, date of racing return, and pre- and post-operative starts and places (1-3), which generated a performance index (PI) and PI per start (PI/S). Chi-squared assessed the effect of categorical variables (sex, limb, fracture type, axiality, SLB injury and pre-surgical racing experience) on racing outcome. Wilcoxon signed-rank test compared pre- and post-operative performance indices. Kruskal-Wallis and Mann-Whitney U tests assessed significance between categorical variables and numerical variables (age, recovery, number of starts (Nstarts), and performance indices). Binary logistical regression performed multivariable analysis. Change in PI and PI/S, and Nstarts were compared between matched controls and cases using Mann-Whitney U tests.

Results: Overall, 86/168; 51.2% (confidence interval (CI): 43.5%-58.9%) horses raced post-operatively. Of the 113 horses that raced pre-operatively, 57 raced post-operatively (50.4%, CI: 41.8%-59.3%). Forelimb fracture cases (42.3%) were less likely to race post-operatively compared with hindlimb cases (65.6%, p = 0.003). In univariable analysis, horses that underwent surgical management of mid-body fractures (15.8%) were less likely to race compared with other fracture types (apical 56.1%, abaxial 60.5% and basal 25%, p = 0.001). Horses undergoing screw-fixation were less likely to race compared with fragment-removal (17.4% vs. 56.6%, p = 0.001). Axiality, pre-operative racing and SLB injury did not affect return-to-racing. No significance was observed for post-operative Nstarts, change in PI, change in PI/S or the return-to-racing proportion between cases and controls.

Main limitation: The retrospective nature and drop-out rate limited post-operative analysis.

Conclusion: Surgical management of apical and abaxial PSBFs via fragment removal is associated with improved post-operative outcomes compared with PSBFs necessitating internal fixation. Limb is a significant determining factor for return to racing. Post-operative racers have good longevity, although reduced PI/S compared with pre-operative performance.

Background: While computed tomographic (CT) myelography is increasingly available and has been evaluated in alive horses, objective criteria for diagnosing cervical vertebral compressive myelopathy (CVCM) are lacking.

Objectives: To establish morphometric dimensions of the cervical vertebral canal and spinal cords from horses with CVCM and compare those to unaffected horses with the use of cone beam CT (CBCT).

Study design: Prospective observational study.

Methods: Four control horses and ten horses with CVCM underwent diagnostic imaging and histopathology. Morphometric measurements were obtained from cervical radiographs and radiographic and CBCT myelography. Receiver operating characteristic curves were generated to establish thresholds of measurements.

Results: Intravertebral sagittal ratios were significantly different between CVCM and control horses. Dorsal myelographic column reduction was significantly different between compressed sites and non-compressed sites. Full myelographic area, dural area, and spinal cord area were significantly smaller in the CVCM horses, and were significantly smaller at compressed sites when compared to non-compressed sites. Reductions of full myelographic area and dural area and ratios of spinal cord area to full myelographic area and dural area were significantly larger at compressed sites when compared to non-compressed sites. Diagnostic thresholds to consider for CVCM are full myelographic area <294 mm², dural area <188 mm², and spinal cord area <104 mm². Compressed sites were associated with thresholds of full myelographic area <274 mm², dural area <188 mm², or reduction of full myelographic area >9%, reduction of dural area >14%, spinal cord area: full myelographic area >36.7%, and spinal cord area: dural area >57.9%.

Main limitations: Small number of horses. CVCM horses were younger than control horses.

Conclusions: CBCT myelography provides quantitative parameters that can support a diagnosis of CVCM and should be used alongside radiographic myelography.

Background: Vitrified embryos ≤300 μm give better pregnancy rates following warming and transfer than larger ones. Embryo recovery undertaken close to when the embryo enters the uterus (Day 6-6.5) helps in the recovery of embryos ≤300 μm. However, flushing early can mean missing an embryo not yet in the uterus, whereas later can result in embryos >300 μm.

Objectives: To evaluate if repeated embryo flushing on consecutive days from Day 6.5 would increase the number of embryos ≤300μm recovered.

Study design: Retrospective case series.

Methods: Four hundred and ninety-six inseminations with cooled (n = 339) or frozen (n = 130) semen were undertaken in 91 mares over a three-year period; pre-ovulatory for cooled and post-ovulatory for frozen semen, with mares checked for ovulation daily or every 6 h, respectively. At a presumed Day 6.5 (cooled semen) or 7 (frozen semen), mares' uteri were flushed, with flushing repeated 24 and 48 h later if no embryo was recovered. Linear mixed-effects models and likelihood ratio tests were used to investigate factors potentially influencing embryo diameter, embryo grade, and oviduct transport time (e.g., semen type, ovulatory drug, stallion age, mare age, season and flush number).

Results: Using repeated flushing, 98.8% (243/246) of embryos recovered were ≤300 μm. Second and third flushes yielded 61 embryos (24.8% of recovered embryos). The only variable that influenced embryo diameter was flush number (p = 0.003); for embryo grade, no variable was significant, whereas oviduct transport time was affected by semen type (p = 0.003), ovulatory drug (p = 0.029) and stallion age (p = 0.005).

Main limitations: Noncontrolled clinical study.

Conclusions: Embryo flushing on consecutive days from the time of expected entry of the embryo into the uterus was effective in collecting embryos ≤300 μm and resulted in additional embryos being retrieved compared with a single flush. Oviductal transport time in some mares is >156 h from ovulation.

Background: Frequent premature atrial complexes (PACs) can increase the risk of atrial fibrillation or atrial tachycardia, and pharmacological therapy can be challenging.

Objective: To report the use of three-dimensional electro-anatomical mapping of PAC originating from the right atrial free wall and treatment by radiofrequency ablation in three horses.

Study design: Retrospective case report.

Case description: Frequent premature atrial complexes (PACs) were diagnosed in three horses. Twelve-lead ECG and vectorcardiography suggested an origin in the right lateral free wall in two horses and the caudal right atrium in one horse. Three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency ablation using the CARTO™ 3 system were performed. Isoprenaline or dobutamine administration allowed activating the focus of PACs during general anaesthesia. Activation mapping using Pattern Matching Filtering identified the origin of PACs at the mid portion of the right atrial free wall in all horses. In the first horse, ablation was not performed due to pacing-induced phrenic nerve stimulation at the site of earliest activation. In the second horse, PACs disappeared after the 18th energy application and were no longer inducible by dobutamine. In the last horse, ablation was not successful in eliminating PACs.

Main limitation: Small number of cases.

Conclusion: The 3D EAM identified the focus of PACs at the right atrial free wall in three horses, revealing it as a possible arrhythmogenic area. Although still challenging, radiofrequency ablation has promise as a treatment to provide a permanent solution for frequent PACs.