Trained to cut? A literature review of veterinary surgical resident training.

A surgical residency trains veterinary graduates to a higher level of expertise in surgical procedures than is possible during veterinary school and prepares a resident to pursue board certification in surgery. The education of veterinary surgical residents has changed minimally since its inception in the twentieth century, and there are insufficient studies to determine if residency programs are producing surgeons with competence in each of the necessary procedural categories. The aims of this review were to report the current theory and methods used to provide surgical education to residents, to discuss the training most likely to create a competent, board-certified surgeon and to review assessment methods used during training. Several literature searches using broad terms such as "veterinary surgery residency," "veterinary surgery resident," and "veterinary surgical training" were performed using PubMed, CAB abstracts, and Google Scholar. Literature pertinent to theory, methods, training, and assessment of veterinary surgical residents was included. The reviewed literature demonstrated the need for research-based learning curves for specific procedures. Simulation training is known to facilitate deliberate practice and should be leveraged where possible to reach competency. The creation of validated assessment methods should be pursued as it enables assessment of competency instead of inferring its development from case logs. Understanding and supporting learner cognition and providing sufficient feedback remain important issues in the field. Surgical educators are urged to continue to search for innovative and evidence-based ways to train competent surgical residents.

Simulating Ovariohysterectomy: What Type of Practice Promotes Short- and Long-Term Skills Retention?

Simulation-based surgical training allows students to learn skills through deliberate practice without the patient risk and stress of operating on a live animal. This study sought to determine the ideal distribution of training sessions to improve short- and long-term retention of the skills necessary to perform a simulated ovariohysterectomy (OVH). Fourth-semester students (n = 102) were enrolled. Students in the weekly instruction group (n = 57) completed 10 hours of training on the OVH simulator, with sessions held at approximately weekly intervals. Students in the monthly instruction group (n = 45) completed the same training with approximately monthly sessions. All students were assessed 1 week (short-term retention test) and 5 months following the last training session (long-term retention test). Students in the weekly instruction group scored higher on their short-term assessment than students in the monthly instruction group (p < .001). However, students' scores in the weekly instruction group underwent a significant decrease between their short- and long-term assessments (p < .001), while the monthly group did not experience a decrease in scores (p < .001). There was no difference in long-term assessment scores between weekly and monthly instruction groups. These findings suggest that if educators are seeking maximal performance at a single time point, scheduling instructional sessions on a weekly basis prior to that time would be superior to monthly sessions, but if educators are concerned with long-term retention of skills, scheduling sessions either on a weekly or monthly basis would accomplish that purpose.

Self-Efficacy and Student Satisfaction in a Clinical-Year Diagnostic Imaging Course Using an Online Instruction Format.

Accurate interpretation of radiographic images is critical to diagnosing clinical patients. Remote instruction in radiology has become more common at veterinary colleges as academic institutions struggle to fill open veterinary radiologist positions and as a result of the COVID-19 pandemic. This study sought to gather the feedback of fourth-year veterinary students via pre- and post-study surveys (n = 45) and focus groups (n = 7) about a newly implemented 2-week long radiology rotation. Ninety-eight percent of students reported having taken an online course before, and on both pre- and post-study surveys, students commonly reported feeling interested, determined, and attentive. On average, students reported that they were neither more nor less engaged than they would have been in an in-person course and that they understood the material neither better nor worse than they would have in an in-person course. Students reported that the key to their success was primarily hard work; secondarily, instructor availability and student ability were important. Students did not rate luck as having much influence on their success. Although diagnostic imaging can be a challenging subject to master, students effectively learned this subject through online instruction. They provided feedback for the course's continued improvement; their comments centered around improved interactivity, including providing automated quiz questions' answers and increased instructor availability. Data collected in this study will help to guide further development of the radiology course.

Online Case-Based Course in Veterinary Radiographic Interpretation Generates Better Short- and Long-Term Learning Outcomes than a Virtual Lecture-Based Course.

Accurate interpretation of radiographs is necessary for the correct diagnosis and treatment of patients. Research has shown that active learning methods, including case-based learning, are superior to passive learning methods, such as lectures.1,2 Short-term learning outcomes were compared between two groups by enrolling 80 fourth-semester veterinary students in either an online case-based radiology course (n = 40) or a virtual lecture-based course (n = 40). Long-term learning outcomes were compared among three groups: one group completed case-based instruction in the fourth semester, followed by lecture-based instruction in the fourth semester (n = 19); the second group completed only lecture-based instruction in the fourth semester (n = 22), and the third group completed lecture-based instruction in the fourth semester, followed by case-based instruction in the fifth semester (n = 9). Learning was assessed using a multiple-choice examination and two independently written small animal radiograph reports. In the fourth semester, students completing the case-based course had higher examination scores and radiograph report scores than students who took the lecture-based course. Students completing the lecture-based course in the fourth semester and the case-based course in the fifth semester wrote better radiograph reports than students who completed both courses in the fourth semester; both groups wrote better reports than students who did not take the case-based course. A case-based diagnostic imaging course may be better than a lecture-based course for both short- and long-term retention of knowledge; however, there is a significant loss of knowledge following an instructional gap, and spaced refreshers may boost retention.

What's the evidence? A review of current instruction and assessment in veterinary surgical education.

Veterinary surgical education is improved by studying the relevant literature. The aim of this literature review was to report the theory and methods used to provide surgical education to veterinary students; to discuss the training most likely to create a competent general practitioner; and to review assessment methods for simulated and live surgeries. The literature reviewed demonstrates that new graduates are expected to perform small animal sterilization, dental extraction, onychectomy, abscess treatment, aural hematoma repair, and mass removal with little or no supervision. Students require repetitive practice to reach competence; some practice can take place in a clinical skills laboratory on models or cadavers. When training novices, distributing practice over a longer time improves retention, but months without practice causes skills to decay. Suturing skills may be taught on models at a ratio of 1 instructor per 10 students. Veterinary students require 6-10 repetitions of each small animal sterilization surgery to reach competence; however, learning curves for other surgeries have not been established. Assessment of surgical skills has been undertaken using objective structured clinical examinations (OSCEs) and observed model and live surgeries. Additional validated rubrics are needed in the field. Surgical educators are urged to continue to search for innovative ways to foster deliberate practice, assess skill, and provide feedback for students.

Remote Assessment of Veterinary Clinical Skills Courses During the COVID-19 Pandemic.

In spring 2020, the COVID-19 pandemic forced educators to adjust the delivery and assessment of curriculum. While didactic courses moved online, laboratory courses were not amenable to this shift. In particular, assessment of clinical skills courses through common methods including objective structured clinical examinations (OSCEs) became inadvisable. This article describes decisions made for first-, second-, and third-year veterinary students (n = 368) with respect to clinical skills at one US college. This includes the remote completion of a surgical skills curriculum using instructional videos and models and the delaying of laboratory sessions deemed impossible to deliver remotely. First- and third-year students were subsequently assessed using modified remote OSCEs. Second-year students were assessed using the standard surgical skills examination, video-recorded. All first- and third-year students successfully passed their OSCE upon either first attempt or remediation. Two second-year students failed their remediation examination and were offered additional faculty tutoring and another remediation attempt at the start of the fall semester. The remediation rate on the surgical skills examination was not different from that of previous years. One incident of suspected academic dishonesty occurred in the first-year OSCE. Students learned surgical skills successfully at home by practicing on models and receiving feedback of their skills on video recordings. While disappointing, one case of academic dishonesty among the 368 total students tested was not surprising. Remote assessment using modified OSCEs and surgical skills exams appears feasible and fair when in-person testing is not possible.

If you build it, they will learn: A review of models in veterinary surgical education.

Surgical skills are learned through deliberate practice, and veterinary educators are increasingly turning to models for teaching and assessing surgical skills. This review article sought to compile and review the literature specific to veterinary surgical skills models, and to discuss the themes of fidelity, educational outcomes, and validity evidence. Several literature searches using broad terms such as "veterinary surgery model," "veterinary surgical model," and "veterinary surgical simulator" were performed using PubMed, CAB abstracts, and Google scholar. All articles describing a model created and utilized for veterinary surgical training were included. Other review articles were used as a source for additional models. Commercially available models were found using review articles, internet browser searches, and communication with veterinary clinical skills educators. There has been an explosion of growth in the variety of small animal surgical task trainers published in the last several decades. These models teach orthopedic surgery, ligation and suturing, open celiotomy and abdominal surgery, sterilization surgeries, and minimally invasive surgeries. Some models were published with accompanying rubrics for learner assessment; these rubrics have been noted where present. Research in veterinary surgical models is expanding and becoming an area of focus for academic institutions. However, there is room for growth in the collection of validity evidence and in development of models for teaching large animal surgery, training surgical residents, and providing continuing education to practitioners. This review can assist with evaluation of current surgical models and trends, and provide a platform for additional studies and development of best practices.

The impact of gel fingernail polish application on the reduction of bacterial viability following a surgical hand scrub.

OBJECTIVE: To determine the effect of gel nail polish application on the reduction of bacterial viability immediately after a surgical hand scrub. STUDY DESIGN: Randomized controlled trial. SAMPLE POPULATION: Ten fingernails each from 40 female health care professionals and students. METHODS: Participants' fingernails were randomized to receive no polish or gel nail polish during a manicure from a licensed manicurist. One day and 14 days after manicure, participants' fingernails were sampled before and after a surgical hand scrub with chlorhexidine gluconate. The samples for each fingernail were serially diluted, plated on a Trypsin sheep blood agar and MacConkey's agar plate, and incubated for 36 h. For each plate, bacterial colony forming units (CFU)/ml were determined. Mixed linear models were used to assess factors associated with the logarithmic reduction of viable bacterial counts from pre- to post-surgical scrub. RESULTS: In the final model, no association was detected between gel nail polish and reduction of viable bacterial count (p = .09). On Day 14, among longer nail lengths (2 to <3-mm and ≥3-mm), surgical scrubs resulted in greater reduction in bacterial counts in left-handed than right-handed participants (p < .01). Increasing nail length was correlated with increased CFU/ml post-scrubbing (p < .001). CONCLUSION: Application of gel nail polish did not seem to affect the ability of surgical scrub to reduce bacterial viability 1 and 14 days after a manicure. CLINICAL IMPACT: This study does not provide evidence to prevent application of gel nail polish on short fingernails in surgeons prior to surgical hand scrub with chlorhexidine gluconate.

Evaluation of an evidence-based veterinary medicine exercise for instruction in clinical year of veterinary medicine program.

INTRODUCTION: Evidence-based veterinary medicine (EBVM) is a fundamental core competency for new graduates. Our objectives were to evaluate clinical students' use, understanding of, and confidence in EBVM before undertaking an exercise consisting of an hour seminar in conjunction with a medical librarian, followed by a journal club and to evaluate students' knowledge of and ability to apply EBVM following the exercise. METHODS: In this cohort study, students undertaking a large animal ambulatory rotation completed questionnaires before the seminar, following the journal club, and at graduation. Students took a Fresno test evaluating EBVM knowledge at the end of the rotation. RESULTS: Prior to the seminar, 94% of students defined EBVM at least somewhat accurately, and 51% reported EBVM was at least 'quite important'. During previous rotations, 71% of students had performed literature searches to answer a clinician-assigned question; 89% had done this to answer their own questions. Students with previous research or EBVM training were more likely to perform self-directed literature searches. The most frequently used resource was textbooks. Eighty-seven per cent and 90% of students found the seminar and journal club, respectively, at least moderately useful in improving EBVM knowledge. CONCLUSIONS: Our results support the inclusion of an EBVM exercise during the clinical year and suggest spaced repetition may be helpful in teaching this topic.

Influence of instructor-to-student ratio for teaching suturing skills with models.

OBJECTIVE: To evaluate the influence of instructor to student ratio on the effectiveness and efficiency of teaching suturing skills to veterinary students. STUDY DESIGN: Prospective randomized study. SAMPLE POPULATION: Second-year veterinary students (N = 121). METHODS: Students were randomly divided into three groups to participate in four 2-hour skills laboratory sessions in which suturing of the subcutaneous tissue was taught by using a simple continuous pattern, suturing of the skin was taught by using continuous patterns, suturing of the skin was taught by using interrupted patterns, and suturing of hollow organs was taught by using inverting patterns. For each laboratory, the groups were taught by using instructor-to-student ratios of 1:6, 1:8, and 1:10 on a rotating basis. Students were surveyed at the end of each laboratory, and underwent individual performance assessments at the end of each laboratory session and again at the end of the semester in an objective structured clinical examination (OSCE). RESULTS: For each of the four in-laboratory assessments and the OSCE, no difference in performance was detected between groups. When they were surveyed, students in all groups reported that there was an adequate number of instructors in the laboratory and that they received help in a timely fashion when help was requested (median for all groups = agree). CONCLUSION: For students with prior surgical skills education and with the use of prelaboratory instructional videos, teaching at the 1:10 instructor-to-student ratio was efficient and effective. CLINICAL SIGNIFICANCE: Good educational outcomes may be reached with a 1:10 instructor-to-student ratio or, potentially, fewer instructors, depending on the educational aids present in the laboratory and students' prior level of experience.

The Impact of Extracurricular Surgical Experience on Veterinary Students' Performance of Canine Ovariohysterectomy and Orchidectomy in a Clinical Skills Curriculum.

Veterinary students may pursue extracurricular surgical experiences before performing ovariohysterectomy or orchidectomy in their veterinary curriculum. We sought to evaluate the impact of these experiences on student confidence and subsequent surgical performance during students' first canine ovariohysterectomy or orchidectomy during their veterinary school curriculum. We enrolled 69 third-year veterinary students to complete pre- and post-operative surveys reporting their confidence to perform surgery and self-assessing their performance. Students had all completed five semesters of surgical skills training on models and cadavers but varied in their participation in extracurricular surgical experiences. A subset of students (n = 27) were digitally recorded while performing ovariohysterectomy (16) or orchidectomy (11). Digital recordings were scored by a blinded rater using task-specific rubrics and a global rating scale, and time to perform the procedure was recorded. The number of extracurricular surgeries students had performed was positively correlated with their confidence to perform orchidectomy (r = .78) but not ovariohysterectomy (r = -.17). There was no correlation between extracurricular surgeries performed and subsequent rubric scores or surgical times for the first ovariohysterectomy (r = -.01 and r = -.14, respectively) or orchidectomy (r = .09 and r = -.18, respectively) performed as part of their veterinary curriculum. Our results suggest that extracurricular surgical experiences may not impart a long-term improvement on performance scores or surgical time during students' first surgery of their veterinary curriculum. Additional research is necessary to clarify how model training and extracurricular surgical experiences on live animals interact to affect students' subsequent surgical performance.

Development and Validation of a Bovine Castration Model and Rubric.

Veterinary students require deliberate practice to reach competence in surgical bovine castration, but animal availability limits opportunities for practice. We sought to create and validate a surgical bovine castration model consisting of a molded silicone scrotum and testicles to allow students to practice this skill without the use of live animals. We sought to validate the model and associated scoring rubric for use in a veterinary clinical skills course. A convenience sample of third-year veterinary students (n = 19) who had never castrated a bovine were randomized into two groups. The traditionally trained (T) group performed castration on a live bull calf after a 50-minute instructional lecture. The model-trained (M) group received the same lecture and a 2-hour clinical skills session practicing bovine castration using the model. All students were subsequently digitally recorded while castrating a live bull calf. Performance recordings were scored by an investigator blinded to group. Survey data were collected from the students and from expert veterinarians testing the model (n = 8). Feedback from both groups was positive. The M group had higher performance scores than the T group (M group, M = 80.6; T group, M = 68.2; p = .005). Reliability of rubric scores was adequate at .74. No difference was found in surgical time (M group, M = 4.5 min; T group, M = 5.5 min; p = .12). Survey feedback indicated that experts and students considered the model useful. Model training improved students' performance scores and provided evidence for validation of the model and rubric.

Educational Research Report Comparison of Three Canine Models for Teaching Veterinary Dental Cleaning.

Veterinary dental cleaning prevents and treats periodontal disease, one of the most common diagnoses in small animal practice. Students learn to perform dental cleaning through deliberate practice, which can be gained through working on models. This study compared educational outcomes after students (n = 36) were randomized to practice on one of three dental cleaning models: a low-fidelity ceramic tile, a mid-fidelity three-dimensional (3D) printed canine skull model, or a high-fidelity canine head model. Students provided survey feedback about their model and later performed a dental cleaning on a canine cadaver head while being video-recorded. Experts (n = 10) provided feedback on each model. Experts agreed that all models were suitable for teaching dental cleaning, but the 3D skull and full head models were more suitable for assessing student skill (p = .002). Students were also more positive about the realism and features of those two models compared to the tile model. Students practicing on each of the models were equally effective at removing calculus from the cadavers' teeth. Students who learned on the tile model were a median of 4 minutes slower to remove calculus from their cadaver's teeth than students who trained on the canine head model. Although students may be more accepting of the 3D skull and full head models, all three models were equally effective at teaching the skill. Experts approved all models for teaching, but recommended the 3D skull or full head model if student skills were to be assessed. Low-fidelity models remain effective training tools with comparable learning outcomes.

Depletion of pulmonary intravascular macrophages rescues inflammation-induced delayed neutrophil apoptosis in horses.

The objective of this study was to determine the effect of pulmonary intravascular macrophage depletion on systemic inflammation and ex vivo neutrophil apoptosis using an experimental model of intestinal ischemia and reperfusion injury in horses. Neutrophils were isolated before and after surgery from horses that were randomized to three treatment groups, namely, sham celiotomy (CEL, n = 4), intestinal ischemia and reperfusion (IR, n = 6), and intestinal ischemia and reperfusion with gadolinium chloride treatment to deplete pulmonary intravascular macrophages (PIMs, IRGC, n = 6). Neutrophil apoptosis was assessed with Annexin V and propidium iodide staining quantified with flow cytometry and caspase-3, caspase-8, and caspase-9 activities in neutrophil lysates. All horses experienced a systemic inflammatory response following surgery. Following surgery, ex vivo neutrophil apoptosis was significantly delayed after 12 or 24 h in culture, except in IRGC horses (12 h: CEL: P = 0.03, IR: P = 0.05, IRGC: P = 0.2; 24 h: CEL: P = 0.001, IR: P = 0.004, IRGC: P = 0.3). Caspase-3, caspase-8, and caspase-9 activities were significantly reduced in neutrophils isolated after surgery and cultured for 12 h in IR horses, but not in IRGC horses (IR caspase-3: P = 0.002, IR caspase-8: P = 0.002, IR caspase-9: P = 0.04). Serum TNF-α concentration was increased in IRGC horses for 6-18 h following jejunal ischemia. Following surgery, ex vivo equine neutrophil apoptosis was delayed via downregulation of caspase activity, which was ameliorated by PIM depletion potentially via upregulation of TNF-α.

Does virtual reality training improve veterinary students' first canine surgical performance?

BACKGROUND: Virtual reality (VR) applications are effective tools in many educational disciplines. A minimally interactive VR application allowing stereoscopic viewing of surgical videos has been developed to aid veterinary students learning to perform surgery. We sought to describe how students used the VR application while preparing to perform their first canine sterilisation surgery and compare surgical performance of students who prepared using traditional methods with students who also used VR. METHODS: Third-year veterinary students (n=44) were randomised into control and VR groups in a parallel superiority randomised controlled trial. All were given lectures, videos and skills practice on models. VR group students were also given a VR application and headset to view stereoscopic surgical videos. Blinded raters scored a subset of students (n=19) as they performed their first canine ovariohysterectomy. RESULTS AND CONCLUSIONS: Groups spent similar time preparing to perform surgery, potentially because of the rigour of students' non-surgical course load. When VR training was added to an already comprehensive surgical skills curriculum, students watched VR videos for a median of 90 min. Groups did not differ in surgical performance scores or time. A larger study of the VR application with prescribed use guidelines would be a helpful subsequent study.

Development and Validation of a Canine Castration Model and Rubric.

Veterinary educators use models to allow repetitive practice of surgical skills leading to clinical competence. Canine castration is a commonly performed procedure that is considered a Day One competency for a veterinarian. In this study, we sought to create and evaluate a canine pre-scrotal closed castration model and grading rubric using a validation framework of content evidence, internal structure evidence, and relationship with other variables. Veterinarians (n = 8) and students (n = 32) were recorded while they performed a castration on the model and provided survey feedback. A subset of the students (n = 7) then performed a live canine castration, and their scores were compared with their model scores. One hundred percent of the veterinarians and 91% of the students reported that the model was helpful in training for canine castration. They highlighted several areas for continued improvement. Veterinarians' model performance scores were significantly higher than students', indicating that the model had adequate features to differentiate expert from novice performance. Students' performance on the model strongly correlated with their performance of live castration (r = .82). Surgical time was also strongly correlated (r = .70). The internal consistency of model and live rubric scores were good at .85 and .94, respectively. The framework supported validation of the model and rubric. The canine castration model facilitated cost-efficient practice in a safe environment in which students received instructor feedback and learned through experience without the risk of negatively affecting a patient's well-being. The strong correlation between model and live animal performance scores suggests that the model could be useful for mastery learning.

Comparison of 2 canine celiotomy closure models for training novice veterinary students.

OBJECTIVE: To compare a low-fidelity foam and fabric (FF) model to a high fidelity silicone (SI) model for teaching canine celiotomy closure. STUDY DESIGN: Prospective blinded comparison of learning outcomes. SAMPLE POPULATION: Second-year veterinary students who had never performed surgery as a primary surgeon (n = 46) and veterinarians experienced in performing canine celiotomy (n = 10). METHODS: Veterinary students performed a digitally recorded celiotomy closure on a canine cadaver before and after participation in 4 facilitated laboratory training sessions on their randomly assigned model. Recordings were scored by masked, trained educators with an 8-item task-specific rubric. Students completed surveys evaluating the models. Experienced veterinarians tested the models and provided feedback on their features. RESULTS: Completed pretest and posttest recordings were available for 38 of 46 students. Students' performance improved regardless of the model used to practice (P = .04). The magnitude of improvement did not differ between the 2 groups (P = .10). All students (n = 46) described their models favorably. Ninety percent of veterinarians thought both models were helpful for training students and gave similar ratings on all measures except for realism, which was rated higher for the SI model's skin (median, agree) compared with the FF model (median, neutral, P = .02). CONCLUSION: Model-based training was effective at improving students' surgical skills. Less experienced learners achieved similar skill gains after practicing with FF or SI models. CLINICAL SIGNIFICANCE: The acquisition of surgical skills required to perform celiotomy closure in companion animals occurs similarly well on models made of foam and fabric or of silicone, providing flexibility in model selection.

Characteristics of parasitic egg shedding over a 1-year period in foals and their dams in 2 farms in central Saskatchewan.

The goals of this study were to report the seasonal shedding patterns of strongyle and Parascaris spp. eggs in repeated fecal samples for mares (n = 38) and foals (n = 39), and to evaluate the efficacy of ivermectin treatment in mares from 2 selected horse breeding farms in central Saskatchewan. Median strongyle fecal egg counts (FEC) peaked in July and August in adult horses. The farms differed significantly (P = 0.0005) in regard to strongyle shedding categories (< 200; 200 to 500; and > 500 eggs/g) over time, but for each individual horse (both farms combined) these categories did not differ over time (P = 0.13) on samples collected in grazing season. When evaluating 3 samples collected fall, summer and fall in 2 consecutive grazing seasons, 94% of horses that shed < 200 eggs/g on 2 initial samples, remained in the same category on the third sample. Mares on each farm didn't differ statistically in shedding categories when comparing September samples from 2 consecutive years (Farm A: P = 0.56, Farm B: P = 0.06). Peak strongyle shedding occurred late fall in the first year of life for foals on Farm A, and in July in the second year of life for foals on Farm B. Parascaris spp. FEC were greatest in foals ≤ 6 months of age, with peak observed when foals were 5 to 6 months old. Ivermectin was 100% effective at reducing strongyle FEC 2 weeks after treatment in adult horses. Horses in Saskatchewan had relatively high strongyle shedding levels, which were significantly different between the farms, and high prevalence of Oxyuris equi. Strongyle shedding consistency was observed for FECs collected from mares in grazing season (July to September).

Caractéristiques de l'excrétion des oeufs de parasites pendant une période de 1 an chez les poulains et leurs mères dans deux fermes du centre de la Saskatchewan. Cette étude avait pour but de dresser un rapport sur les tendances d'excrétion saisonnière des oeufs des strongyles et de Parascaris spp. dans des prélèvements fécaux répétés pour les juments (n = 38) et les poulains (n = 39) et d'évaluer l'efficacité du traitement à l'ivermectine chez deux juments provenant de deux fermes d'élevage de chevaux dans le centre de la Saskatchewan. Les comptes médians d'oeufs fécaux des strongyles ont culminé en juillet et en août chez les chevaux adultes. Les fermes présentaient des différences significatives (P = 0,0005) à l'égard des catégories d'excrétion des strongyles (< 200; de 200 à 500; et > 500 oeufs/g) dans le temps, mais, pour chaque cheval individuel (les deux fermes combinées), ces catégories ne présentaient pas de différences à la longue (P = 0,13) pour les échantillons prélevés durant la saison de pâturage. Lors de l'évaluation des reois échantillons prélevés à l'automne, à l'été et à l'automne pendant deux saisons de pâturage consécutives, 94 % des chevaux qui avaient excrété < 200 oeufs/g pour deux prélèvements initiaux, sont demeurés dans la même catégorie pour le troisième échantillon. Les juments de chaque ferme ne présentaient pas de différences statistiques pour les catégories d'excrétion lorsque l'on comparait les échantillons de septembre provenant de deux années consécutives (Ferme A : P = 0,56, Ferme B : P = 0,06). L'excrétion des strongyles a culminé à la fin de l'automne pendant la première année de vie pour les poulains de la Ferme A et en juillet de la deuxième année de vie pour les poulains de la Ferme B. Les comptes d'oeufs fécaux de Parascaris spp. étaient les plus importants chez les poulains âgés de ≤ 6 mois et le point culminant était observé lorsque les poulains étaient âgés de 5 ou 6 mois. L'ivermectine était efficace à 100 % pour réduire les comptes d'oeufs fécaux 2 semaines après le traitement chez les chevaux adultes. Les chevaux de la Saskatchewan ont présenté des taux d'excrétion relativement élevés de strongyles, qui étaient significativement différents entre les fermes, et une forte prévalence d'Oxyuris equi. La constance de l'excrétion des strongyles a été observée pour les comptes d'oeufs fécaux obtenus auprès des juments pendant la saison de pâturage (de juillet à septembre).(Traduit par Isabelle Vallières).

Role of toll-like receptor 4 and caspase-3, -8, and -9 in lipopolysaccharide-induced delay of apoptosis in equine neutrophils.

OBJECTIVE To evaluate the effect of lipopolysaccharide (LPS) on apoptosis of equine neutrophils in vitro. SAMPLE Venous blood samples from 40 adult horses. PROCEDURES Neutrophils were isolated from blood samples and cultured with or without LPS from Escherichia coli O55:B5 for 12 or 24 hours. Neutrophil apoptosis was assessed by use of cytologic examination, annexin V and propidium iodide staining quantified with flow cytometry, coincubation with inducers of intrinsic and extrinsic apoptosis or a toll-like receptor (TLR) 4 inhibitor, and measurement of caspase-3, -8, and -9 activities. RESULTS Treatment with LPS resulted in a significant delay in apoptosis after incubation for 12 and 24 hours (neutrophils from blood samples of 40 horses). There was a significant correlation between increases in LPS dose and decreases in apoptosis after incubation for 24 hours (3 experiments, each of which involved neutrophils obtained from the same 3 horses at 3 separate times). Caspase-9 activity, but not caspase-3 or -8 activity, was significantly reduced in LPS-treated neutrophils after incubation for 12 hours (neutrophils from blood samples of 17 horses). Treatment with a TLR4 inhibitor or intrinsic and extrinsic inducers of apoptosis prevented LPS-delayed apoptosis. CONCLUSIONS AND CLINICAL RELEVANCE LPS treatment delayed apoptosis of equine neutrophils in vitro for up to 24 hours in a dose-dependent manner by alteration of the intrinsic pathway of apoptosis and was dependent on TLR4 signaling. Increased neutrophil life span may contribute to the development of a systemic inflammatory response syndrome in endotoxemic horses.

Equine neutrophils and their role in ischemia reperfusion injury and lung inflammation.

Horses are susceptible to a multitude of inflammatory conditions that are characterized by a strong neutrophilic response. Here, we review basic equine neutrophil biology and explore the role of neutrophils in inflammatory conditions with emphasis on intestinal ischemia and reperfusion injury and lung inflammation. In addition, unique aspects of equine neutrophil biology have been highlighted. Neutrophils comprise the highest proportion of circulating white blood cells in equine blood. The concentration of circulating equine neutrophils is a primary indicator of systemic inflammation. Additionally, equine neutrophils exposed to various stimulants develop "toxic" changes characterized as cytoplasmic basophilia, presence of Döhle bodies, cytoplasmic vacuolation and toxic granulation. In contrast to human neutrophils, equine neutrophils fail to undergo chemotaxis in response to the peptide N-formyl-methionyl-leucyl-phenylalanine and are dependent on the addition of arachidonic acid due to reduced activity of phospholipase A2 to synthesize leukotrienes as part of the arachidonic acid pathway. Understanding the biologic function of neutrophils in horses is integral to developing methods to modulate inflammation associated with ischemia reperfusion injury and lung disease.