Comparison of postweaning bovine respiratory disease treatment rates between non-vaccinated control beef calves and calves variably primed and boosted using commercially available bovine coronavirus vaccines.

Objective: Bovine respiratory disease (BRD) and overall postweaning treatment rates were compared among 3 groups of calves either differentially primed and boosted with commercially available bovine coronavirus (BCoV) vaccine or not vaccinated against BCoV. Animals: Commercial heifer and steer beef calves born in April and May 2022. Procedure: In June 2022, calves were randomly enrolled into 3 treatment groups. Those in 2 groups [V1 (n = 160) and V2 (n = 160)] were administered a mucosal priming dose of 1 of 2 commercial BCoV vaccines; those in the 3rd group [CTL (n = 151)] were unvaccinated against BCoV. The V1 and V2 groups were boosted by intramuscular injection pre-weaning with the same vaccine used for priming. Weaning occurred 3 wk after the last preweaning processing day. Ranch staff used a BRD case definition provided by their herd veterinarian to identify, treat, and record treatments for 45 d post-weaning. Results: Postweaning BRD treatment rates for V1, V2, and CTL were 7%, 9%, and 14%, respectively. The CTL calves had 2.2× greater odds of receiving treatment for BRD than V1 calves. There were no differences in odds of treatment between CTL and V2 calves or V1 and V2 calves. Conclusion: In a herd with previously diagnosed BCoV BRD cases, prime-boost vaccination of calves is associated with a difference in odds of BRD treatment post-weaning compared to not vaccinating calves against BCoV. Clinical relevance: Prime-boost vaccination with commercial BCoV vaccine may be an important management tool for herds with known BCoV BRD outbreaks.

Comparaison des taux de traitement des maladies respiratoires bovines après le sevrage entre des veaux de boucherie témoins non vaccinés et des veaux vaccinés amorce-rappel de manière variable à l'aide de vaccins contre le coronavirus bovin commercialement disponibles. Objectif: La maladie respiratoire bovine (BRD) et les taux globaux de traitement post-sevrage ont été comparés parmi 3 groupes de veaux soit vaccinés de manière différentielle et avec un rappel avec le vaccin contre le coronavirus bovin (BCoV) disponible commercialement, soit non vaccinés contre le BCoV. Animaux: Génisses et veaux de boucherie commerciaux nés en avril et mai 2022. Procédure: En juin 2022, les veaux ont été randomisés lors du recrutement dans 3 groupes de traitement. Ceux des 2 groupes [V1 (n = 160) et V2 (n = 160)] ont reçu une dose d'amorce par voie muqueuse de l'un des deux vaccins commerciaux BCoV; ceux du 3ème groupe [CTL (n = 151)] n'étaient pas vaccinés contre le BCoV. Les groupes V1 et V2 ont eu un rappel par injection intramusculaire avant le sevrage avec le même vaccin que celui utilisé pour l'amorçage. Le sevrage a eu lieu 3 semaines après le dernier jour de conditionnement pré-sevrage. Le personnel du ranch a utilisé une définition de cas de BRD fournie par le vétérinaire de leur troupeau pour identifier, traiter et enregistrer les traitements pendant 45 jours après le sevrage. Résultats: Les taux de traitement BRD post-sevrage pour V1, V2 et CTL étaient respectivement de 7 %, 9 % et 14 %. Les veaux CTL avaient 2,2 fois plus de chances de recevoir un traitement contre la BRD que les veaux V1. Il n'y avait aucune différence dans les probabilités de traitement entre les veaux CTL et V2 ou entre les veaux V1 et V2. Conclusion: Dans un troupeau avec des cas de BRD causés par le BCoV déjà diagnostiqués, la vaccination amorce-rappel des veaux est associée à une différence de probabilité de traitement par le BRD après le sevrage par rapport à la nonvaccination des veaux contre le BCoV. Pertinence clinique: La vaccination amorce-rappel avec le vaccin commercial BCoV peut être un outil de gestion important pour les troupeaux présentant des foyers connus de BCoV BRD.(Traduit par Dr Serge Messier).

Identification of genetic markers of resistance to macrolide class antibiotics in Mannheimia haemolytica isolates from a Saskatchewan feedlot.

Mannheimia haemolytica is a major contributor to bovine respiratory disease (BRD), which causes substantial economic losses to the beef industry, and there is an urgent need for rapid and accurate diagnostic tests to provide evidence for treatment decisions and support antimicrobial stewardship. Diagnostic sequencing can provide information about antimicrobial resistance genes in M. haemolytica more rapidly than conventional diagnostics. Realizing the full potential of diagnostic sequencing requires a comprehensive understanding of the genetic markers of antimicrobial resistance. We identified genetic markers of resistance in M. haemolytica to macrolide class antibiotics commonly used for control of BRD. Genome sequences were determined for 99 M. haemolytica isolates with six different susceptibility phenotypes collected over 2 years from a feedlot in Saskatchewan, Canada. Known macrolide resistance genes estT, msr(E), and mph(E) were identified in most resistant isolates within predicted integrative and conjugative elements (ICEs). ICE sequences lacking antibiotic resistance genes were detected in 10 of 47 susceptible isolates. No resistance-associated polymorphisms were detected in ribosomal RNA genes, although previously unreported mutations in the L22 and L23 ribosomal proteins were identified in 12 and 27 resistant isolates, respectively. Pangenome analysis led to the identification of 79 genes associated with resistance to gamithromycin, of which 95% (75 of 79) had no functional annotation. Most of the observed phenotypic resistance was explained by previously identified antibiotic resistance genes, although resistance to the macrolides gamithromycin and tulathromycin was not explained in 39 of 47 isolates, demonstrating the need for continued surveillance for novel determinants of macrolide resistance.IMPORTANCEBovine respiratory disease is the costliest disease of beef cattle in North America and the most common reason for injectable antibiotic use in beef cattle. Metagenomic sequencing offers the potential to make economically significant reductions in turnaround time for diagnostic information for evidence-based selection of antibiotics for use in the feedlot. The success of diagnostic sequencing depends on a comprehensive catalog of antimicrobial resistance genes and other genome features associated with reduced susceptibility. We analyzed the genome sequences of isolates of Mannheimia haemolytica, a major bovine respiratory disease pathogen, and identified both previously known and novel genes associated with reduced susceptibility to macrolide class antimicrobials. These findings reinforce the need for ongoing surveillance for markers of antimicrobial resistance to support improved diagnostics and antimicrobial stewardship.

Complete circular assembly of Histophilus somni PDS1537697-81-1 genome and phenotypic characterization of its antibiotic susceptibility.

A Histophilus somni isolate from a clinically healthy, fall-placed calf was obtained upon arrival to a commercial feedlot. Fall-placed calves are commonly viewed to be at high risk for the development of bovine respiratory disease. The isolate was phenotyped for antimicrobial susceptibility and sequenced to obtain a complete, circular, genome assembly.

Bacterial enrichment prior to third-generation metagenomic sequencing improves detection of BRD pathogens and genetic determinants of antimicrobial resistance in feedlot cattle.

Introduction: Bovine respiratory disease (BRD) is one of the most important animal health problems in the beef industry. While bacterial culture and antimicrobial susceptibility testing have been used for diagnostic testing, the common practice of examining one isolate per species does not fully reflect the bacterial population in the sample. In contrast, a recent study with metagenomic sequencing of nasal swabs from feedlot cattle is promising in terms of bacterial pathogen identification and detection of antimicrobial resistance genes (ARGs). However, the sensitivity of metagenomic sequencing was impeded by the high proportion of host biomass in the nasal swab samples. Methods: This pilot study employed a non-selective bacterial enrichment step before nucleic acid extraction to increase the relative proportion of bacterial DNA for sequencing. Results: Non-selective bacterial enrichment increased the proportion of bacteria relative to host sequence data, allowing increased detection of BRD pathogens compared with unenriched samples. This process also allowed for enhanced detection of ARGs with species-level resolution, including detection of ARGs for bacterial species of interest that were not targeted for culture and susceptibility testing. The long-read sequencing approach enabled ARG detection on individual bacterial reads without the need for assembly. Metagenomics following non-selective bacterial enrichment resulted in substantial agreement for four of six comparisons with culture for respiratory bacteria and substantial or better correlation with qPCR. Comparison between isolate susceptibility results and detection of ARGs was best for macrolide ARGs in Mannheimia haemolytica reads but was also substantial for sulfonamide ARGs within M. haemolytica and Pasteurella multocida reads and tetracycline ARGs in Histophilus somni reads. Discussion: By increasing the proportion of bacterial DNA relative to host DNA through non-selective enrichment, we demonstrated a corresponding increase in the proportion of sequencing data identifying BRD-associated pathogens and ARGs in deep nasopharyngeal swabs from feedlot cattle using long-read metagenomic sequencing. This method shows promise as a detection strategy for BRD pathogens and ARGs and strikes a balance between processing time, input costs, and generation of on-target data. This approach could serve as a valuable tool to inform antimicrobial management for BRD and support antimicrobial stewardship.

Variation in Pen-Level Prevalence of BRD Bacterial Pathogens and Antimicrobial Resistance Following Feedlot Arrival in Beef Calves.

Antimicrobials are crucial for treating bovine respiratory disease (BRD) in beef feedlots. Evidence is needed to support antimicrobial use (AMU) decisions, particularly in the early part of the feeding period when BRD risk is highest. The study objective was to describe changes in prevalence and antimicrobial susceptibility of BRD bacterial pathogens at feedlot processing (1 day on feed (1DOF)), 12 days later (13DOF), and for a subset at 36DOF following metaphylactic antimicrobial treatment. Mixed-origin steer calves (n = 1599) from Western Canada were managed as 16 pens of 100 calves, receiving either tulathromycin (n = 1199) or oxytetracycline (n = 400) at arrival. Deep nasopharyngeal swabs collected at all time points underwent culture and antimicrobial susceptibility testing (AST). Variability in the pen-level prevalence of bacteria and antimicrobial susceptibility profiles were observed over time, between years, and metaphylaxis options. Susceptibility to most antimicrobials was high, but resistance increased from 1DOF to 13DOF, especially for tetracyclines and macrolides. Simulation results suggested that sampling 20 to 30 calves per pen of 200 reflected the relative pen-level prevalence of the culture and AST outcomes of interest. Pen-level assessment of antimicrobial resistance early in the feeding period can inform the evaluation of AMU protocols and surveillance efforts and support antimicrobial stewardship in animal agriculture.

Laboratory tools for the direct detection of bacterial respiratory infections and antimicrobial resistance: a scoping review.

Rapid laboratory tests are urgently required to inform antimicrobial use in food animals. Our objective was to synthesize knowledge on the direct application of long-read metagenomic sequencing to respiratory samples to detect bacterial pathogens and antimicrobial resistance genes (ARGs) compared to PCR, loop-mediated isothermal amplification, and recombinase polymerase amplification. Our scoping review protocol followed the Joanna Briggs Institute and PRISMA Scoping Review reporting guidelines. Included studies reported on the direct application of these methods to respiratory samples from animals or humans to detect bacterial pathogens ±ARGs and included turnaround time (TAT) and analytical sensitivity. We excluded studies not reporting these or that were focused exclusively on bioinformatics. We identified 5,636 unique articles from 5 databases. Two-reviewer screening excluded 3,964, 788, and 784 articles at 3 levels, leaving 100 articles (19 animal and 81 human), of which only 7 studied long-read sequencing (only 1 in animals). Thirty-two studies investigated ARGs (only one in animals). Reported TATs ranged from minutes to 2 d; steps did not always include sample collection to results, and analytical sensitivity varied by study. Our review reveals a knowledge gap in research for the direct detection of bacterial respiratory pathogens and ARGs in animals using long-read metagenomic sequencing. There is an opportunity to harness the rapid development in this space to detect multiple pathogens and ARGs on a single sequencing run. Long-read metagenomic sequencing tools show potential to address the urgent need for research into rapid tests to support antimicrobial stewardship in food animal production.

Antimicrobial resistance in generic E. coli isolated from western Canadian cow-calf herds.

Objective: To examine antimicrobial resistance (AMR) in commensal fecal Escherichia coli (E. coli) from extensively managed beef calves and cows in western Canada and describe the differences among cows and calves in the spring and fall. Animal: Beef cattle, cow-calf. Procedure: Antimicrobial susceptibility testing was conducted on generic E. coli isolates collected from 388 calves and 387 cows from 39 herds following calving in 2021, 419 calves from 39 herds near weaning, and 357 cows from 36 herds at pregnancy testing. Minimum inhibitory concentrations were measured with the NARMS CMV5AGNF plate for Gram-negative bacteria and interpreted using Clinical and Laboratory Standards Institute standard breakpoints for humans. Results: Only 16% (242/1551) of all isolates from 97% (38/39) of herds were resistant to ≥ 1 antimicrobial. Generic E. coli isolates were most commonly resistant to sulfisoxazole (11%, 175/1551), followed by tetracycline (9.3%, 145/1551) and chloramphenicol (3.5%, 55/1551). Isolates from calves in the spring were more likely to be resistant to sulfisoxazole, tetracycline, and chloramphenicol than those from cows in the spring or calves in the fall. Multiclass-resistant isolates were identified in 5% (39/807) of calves. Only 2 isolates recovered from cows were resistant to antimicrobials of very high importance for human health. Conclusion and clinical relevance: Most generic E. coli isolates were pansusceptible. The observed resistance patterns were consistent with earlier studies of AMR from commensal E. coli in this region. Baseline AMR data for cow-calf herds are not currently collected as part of routine surveillance, but are essential to inform antimicrobial use policy and stewardship.

Résistance aux antimicrobiens chez E. coli générique isolé dans des troupeaux vache-veau de l'Ouest canadien. Objectif: Examiner la résistance aux antimicrobiens (RAM) chez Escherichia coli de la flore fécale commensale (E. coli) provenant de veaux et de vaches de boucherie en élevage extensif dans l'ouest du Canada et décrire les différences entre les vaches et les veaux au printemps et à l'automne. Animal: Bovins de boucherie, vache-veau. Procédure: Des tests de sensibilité aux antimicrobiens ont été effectués sur des isolats génériques d'E. coli collectés auprès de 388 veaux et 387 vaches de 39 troupeaux après le vêlage en 2021, de 419 veaux de 39 troupeaux à l'approche du sevrage et de 357 vaches de 36 troupeaux lors des tests de gestation. Les concentrations minimales inhibitrices ont été mesurées avec la plaque NARMS CMV5AGNF pour les bactéries à Gram négatif et interprétées à l'aide des seuils standard pour les humains du Clinical and Laboratory Standards Institute. Résultats: Seulement 16 % (242/1 551) de tous les isolats provenant de 97 % (38/39) des troupeaux étaient résistants à ≥ 1 antimicrobien. Les isolats génériques d'E. coli étaient le plus souvent résistants au sulfisoxazole (11 %, 175/1 551), suivi de la tétracycline (9,3 %, 145/1 551) et du chloramphénicol (3,5 %, 55/1 551). Les isolats provenant des veaux au printemps étaient plus susceptibles d'être résistants au sulfisoxazole, à la tétracycline et au chloramphénicol que ceux provenant des vaches au printemps ou des veaux à l'automne. Des isolats résistants à plusieurs classes ont été identifiés chez 5 % (39/807) des veaux. Seuls deux isolats récupérés chez des vaches étaient résistants à des antimicrobiens de très haute importance pour la santé humaine. Conclusion et pertinence clinique: La plupart des isolats génériques d'E. coli étaient sensibles à l'ensemble des antimicrobiens. Les profils de résistance observés concordaient avec les études antérieures sur la RAM provenant d'E. coli commensal dans cette région. Les données de base sur la RAM pour les troupeaux vache-veau ne sont pas actuellement recueillies dans le cadre de la surveillance de routine, mais elles sont essentielles pour éclairer la politique et la gestion de l'utilisation des antimicrobiens.(Traduit par Dr Serge Messier).

Antimicrobial resistance in Enterococcus isolated from western Canadian cow-calf herds.

BACKGROUND: Data on antimicrobial resistance (AMR) in cow-calf herds is limited and there have been no Canadian studies examining AMR in Enterococcus in cow-calf herds. Enterococcus is a ubiquitous Gram-positive indicator of AMR for enteric organisms that is also important in human health. The objective of this study was to describe AMR in specific Enterococcus species of interest from cow-calf herds; highlighting differences in AMR among isolates from cows and calves and samples collected in the spring and fall. Isolates (n = 1505) were examined from 349 calves and 385 cows from 39 herds in the spring of 2021 and 413 calves from 39 herds and 358 cows from 36 herds in the fall of 2021. Enterococcus species were identified using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight mass spectrometry (MALDI-TOF MS) and antimicrobial susceptibility testing was completed based on a prioritization scheme for importance to human health and using the National Antimicrobial Resistance Monitoring System (NARMS) Gram positive Sensititre broth microdilution panel. RESULTS: Resistance was observed to at least one antimicrobial in 86% (630/734) of isolates from the spring and 84% (644/771) of isolates from the fall. The most common types of resistance across all species were: lincomycin, quinupristin/dalfopristin, daptomycin, ciprofloxacin, and tetracycline. However, the proportion of isolates with AMR varied substantially based on species. Multiclass resistance, defined as resistance to ≥3 antimicrobial classes after excluding intrinsic resistance, was highest in isolates from calves in the spring (6.9%) (24/349) and cows in the fall (6.7%) (24/357). Differences in resistance were seen between cows and calves in the spring and fall as well as across seasons, with no differences seen between cows and calves in the fall. CONCLUSIONS: While most Enterococcus isolates were resistant to at least one antimicrobial, questions remain regarding species differences in intrinsic resistance and the accuracy of certain antimicrobial breakpoints for specific Enterococcus spp. As a result, some species-specific AMR profiles should be interpreted with caution. Despite these constraints, Enterococcus species are important indicator organisms for AMR and resulting data can be used to inform stewardship initiatives.

Producer attitudes regarding antimicrobial use and resistance in Canadian cow-calf herds.

Objective: To describe producer attitudes toward antimicrobial use (AMU) and antimicrobial resistance (AMR), identify factors associated with attitudes, and inform stewardship initiatives. Animal: Beef cattle, cow-calf. Procedure: Cow-calf producers from the Canadian Cow-Calf Surveillance Network (C3SN) completed a survey (n = 146) on producers' attitudes toward AMU, AMR, and impacts of recent regulatory changes requiring a prescription for the purchase of medically important antimicrobials (MIA). Results: Most producers (78%, 114/146) reported being aware of initiatives to improve antimicrobial stewardship within the beef industry and 67% (97/146) indicated that AMR was a highly important issue to the industry and producers personally. Almost half of producers reported concerns that AMR development has impacted AMU decisions on their operations. Overall, veterinarians were producers' primary source of information regarding AMU, including treatment protocols, stewardship programs, and regulatory changes. Following introduction of the 2018 prescription-only regulations, 95% (138/146) of producers reported no change in AMU on their operations. Similarly, 77% (112/146) of producers reported no change in antimicrobial product access, whereas 63% (91/146) reported no change in cost. Conclusion: Most producers reported little change in access to antimicrobials and in AMU following the introduction of regulations requiring a prescription for MIA. Clinical relevance: Producers rely on veterinarians as their primary source of information regarding antimicrobial regulations and AMU. It is therefore important for veterinarians to understand their role as educators for beef cow-calf producers. Ultimately, veterinarians and producers need to work together to ensure that the health and welfare of animals are protected while using antimicrobials in a responsible manner.

Attitudes des producteurs à l'égard de l'utilisation des antimicrobiens et de la résistance dans les troupeaux vache-veau canadiens. Objectif: Décrire les attitudes des producteurs à l'égard de l'utilisation des antimicrobiens (AMU) et de la résistance aux antimicrobiens (RAM), identifier les facteurs associés à ces attitudes et les informations sur les initiatives de gouvernance. Animal: Bovins de boucherie, vache-veau. Procédure: Les producteurs naisseurs du Réseau canadien de surveillance vache-veau (C3SN) ont répondu à une enquête (n = 146) sur les attitudes des producteurs à l'égard de l'AMU, de la RAM et des impacts des récents changements réglementaires exigeant une ordonnance pour l'achat d'antimicrobiens médicalement importants (MIA). Résultats: La plupart des producteurs (78 %, 114/146) ont déclaré être au courant des initiatives visant à améliorer la gouvernance des antimicrobiens au sein de l'industrie du bœuf et 67 % (97/146) ont indiqué que la RAM était un problème très important pour l'industrie et les producteurs personnellement. Près de la moitié des producteurs ont fait part de leurs inquiétudes quant au fait que le développement de la RAM ait un impact sur les décisions d'AMU sur leurs opérations. Dans l'ensemble, les médecins vétérinaires étaient la principale source d'information des producteurs concernant l'AMU, y compris les protocoles de traitement, les programmes de gouvernance et les changements réglementaires. À la suite de l'introduction de la réglementation sur prescription uniquement en 2018, 95 % (138/146) des producteurs n'ont signalé aucun changement dans l'AMU de leurs opérations. De même, 77 % (112/146) des producteurs n'ont signalé aucun changement dans l'accès aux produits antimicrobiens, tandis que 63 % (91/146) n'ont signalé aucun changement dans le coût. Conclusion: La plupart des producteurs ont signalé peu de changements dans l'accès aux antimicrobiens et dans l'AMU par suite de l'introduction de réglementations exigeant une prescription pour le MIA. Pertinence clinique: Les producteurs comptent sur les médecins vétérinaires comme principale source d'information concernant la réglementation antimicrobienne et l'AMU. Il est donc important que les médecins vétérinaires comprennent leur rôle d'éducateurs auprès des producteurs de vaches-veaux de boucherie. En fin de compte, les médecins vétérinaires et les producteurs doivent travailler ensemble pour garantir la protection de la santé et du bien-être des animaux tout en utilisant les antimicrobiens de manière responsable.(Traduit par Dr Serge Messier).

Vaccine use in Canadian cow-calf herds and opportunities for improvement.

Vaccinations are one of the most impactful tools available to cow-calf producers to control within herd disease and later, in feedlots. While vaccine use has been studied across Canada, inconsistent and variable regional data makes analysis and interpretation difficult. The objective of this study was to describe vaccination protocols and factors associated with vaccine use in Canadian cow-calf herds and define associations between vaccine use and productivity outcomes. Surveys describing vaccine use in 2020 were collected from 131 cow-calf herds (40 eastern, 91 western), recruited through a national beef cattle surveillance program. Ninety-two percent of cows and replacement heifers, and 72% of bulls were vaccinated with Infectious Bovine Rhinotracheitis (IBR), Bovine Viral Diarrhea Virus (BVDV), Parainfluenza3 Virus (PI3), and Bovine Respiratory Syncytial Virus (BRSV). At least half of cows and bulls were vaccinated for clostridial pathogens and cows and heifers for viral calf scours. Clostridial vaccines were significantly more likely to be used in western Canada compared to eastern Canada. While 92% of producers vaccinated suckling calves against IBR/BRSV/PI3, only 47% provided a second vaccine prior to weaning; 78% of calves were also vaccinated at least once for BVDV before weaning. Producers who vaccinated calves against IBR/BRSV/PI3 before 3 months of age provided a second dose prior to weaning more often than producers who administer the first IBR/BRSV/PI3 vaccine later. Vaccine use has increased across Canada, particularly in calves, prior to weaning. Relative to label recommendations for annual vaccination, clostridial vaccines were generally underutilized in cows and bulls, and by producers in eastern Canada as compared to western Canada. Opportunities also exist to improve adherence to label recommendations for the booster dose of scours vaccine when used in bred replacement heifers. Protocols including product choices, the timing and boosting of respiratory vaccines in nursing calves vary widely across herds. Use of intranasal vaccines in neonatal calves less than 2 weeks old has increased in western Canada compared to previous reports. There is a need to better understand how timing of vaccination in nursing calves contributes to effectiveness, for respiratory disease in nursing and weaned calves.

Complete genome sequence of Mannheimia bovis isolated from a healthy feedlot calf in Saskatchewan, Canada.

A lack of whole genome sequences for Mannheimia spp. other than Mannheimia haemolytica complicates their identification. Here, we present the genome sequence of Mannheimia bovis 39324.S-11, isolated from a healthy calf on a feedlot in Saskatchewan, Canada, and compare it to ZY190616T, which is currently the only other isolate of M. bovis for which sequence is publicly available.

Antimicrobial Use in Canadian Cow-Calf Herds.

Despite growing concern surrounding antimicrobial use (AMU) and the importance of cow-calf herds to the Canadian livestock industry, surveillance of AMU in cow-calf herds to inform antimicrobial stewardship programs has been sporadic. Producers from the Canadian Cow-Calf Surveillance Network (87%, 146/168) provided data and almost all reported AMU in at least one animal (99%, 145/146 herds) in 2019-2020. The most common reasons for AMU were treatment of respiratory disease in nursing calves in 78% of herds and neonatal diarrhea in 67% of herds, as well as for lameness in cows in 83% of herds. However, most herds treated <5% of animals for these reasons. Less than 2.5% of herds treated more than 30% of calves for either bovine respiratory disease or neonatal diarrhea and no herds treated more than 30% of cows for lameness. The most frequently reported antimicrobial was oxytetracycline in 81% of herds, followed by florfenicol in 73% of herds. Antimicrobials with very high importance to human health, such as ceftiofur, were used at least once by 20% of herds but were only used in >30% of nursing calves from one herd. Similarly, while 56% of herds used macrolides at least once, within-herd use was the highest in nursing calves where <4% of herds reported use in >30% of animals. Herds using artificial insemination and calving in the winter were more likely (p = 0.05) to treat >5% of nursing calves for respiratory disease, suggesting the importance of vaccination programs for herds at risk. Overall, AMU was similar to previous Canadian studies; however, the percentage of herds using macrolides had increased from a comparable study in 2014.

Factors associated with antimicrobial resistant enterococci in Canadian beef cattle: A scoping review.

Introduction: Antimicrobial resistance (AMR) is a global health concern, occurring when bacteria evolve to render antimicrobials no longer effective. Antimicrobials have important roles in beef production; however, the potential to introduce AMR to people through beef products is a concern. This scoping review identifies factors associated with changes in the prevalence of antimicrobial-resistant Enterococcus spp. applicable to the Canadian farm-to-fork beef continuum. Methods: Five databases (MEDLINE, BIOSIS, Web of Science, Embase, and CAB Abstracts) were searched for articles published from January 1984 to March 2022, using a priori inclusion criteria. Peer-reviewed articles were included if they met all the following criteria: written in English, applicable to the Canadian beef production context, primary research, in vivo research, describing an intervention or exposure, and specific to Enterococcus spp. Results: Out of 804 screened articles, 26 were selected for inclusion. The included articles discussed 37 factors potentially associated with AMR in enterococci, with multiple articles discussing at least two of the same factors. Factors discussed included antimicrobial administration (n = 16), raised without antimicrobials (n = 6), metal supplementation (n = 4), probiotics supplementation (n = 3), pen environment (n = 2), essential oil supplementation (n = 1), grass feeding (n = 1), therapeutic versus subtherapeutic antimicrobial use (n = 1), feeding wet distiller grains with solubles (n = 1), nutritional supplementation (n = 1) and processing plant type (n = 1). Results were included irrespective of their quality of evidence. Discussion: Comparability issues arising throughout the review process were related to data aggregation, hierarchical structures, study design, and inconsistent data reporting. Findings from articles were often temporally specific in that resistance was associated with AMR outcomes at sampling times closer to exposure compared to studies that sampled at longer intervals after exposure. Resistance was often nuanced to unique gene and phenotypic resistance patterns that varied with species of enterococci. Intrinsic resistance and interpretation of minimum inhibitory concentration varied greatly among enterococcal species, highlighting the importance of caution when comparing articles and generalizing findings. Systematic Review Registration: [http://hdl.handle.net/1880/113592].

Changes in the phenotypic susceptibility of Mannheimia haemolytica isolates to macrolide antimicrobials during the early feeding period following metaphylactic tulathromycin use in western Canadian feedlot calves.

Cattle at high-risk for bovine respiratory disease on entry to western Canadian feedlots are often treated metaphylactically with antimicrobials from the macrolide class. High levels of resistance to macrolides have been reported in Mannheimia haemolytica isolates from clinical samples, but it is less clear whether this trend extends to the broader feedlot population. The objective was to describe near-term [< 40 days on feed (DOF)] changes in the recovery and susceptibility of M. haemolytica isolates from healthy feedlot calves after metaphylactic exposure to tulathromycin. Eight cohorts of 100 calves (n = 800) were sampled via deep nasopharyngeal swab at entry processing (i.e., before metaphylaxis, at 1 DOF) and again at 13 DOF. Ten calves from each cohort (n = 80) were randomly sampled a third time at 36 DOF. Recovery of M. haemolytica isolates across all cohorts increased over the study period, from 33% (95% CI: 26.5 to 40.2%) at 1 DOF to 75% (95% CI: 71.4 to 78.3%) at 36 DOF. A significant shift in the minimum inhibitory concentration (MIC) distribution of tulathromycin from 1 DOF (MIC90 ≤ 8 µg/mL) to 13 DOF (MIC90 > 64 µg/mL) was observed. A subset of 36 isolates from 13 DOF screened for macrolide resistance genes via multiplex polymerase chain reaction all harbored the msrE and mphE genes. Recovery of M. haemolytica at 13 and 36 DOF did not decline in response to metaphylactic use of tulathromycin; conversely, we inferred the potential for rapid inter-pen spread of a macrolide-resistant clone by 13 DOF in 6 of 8 pens under selective pressure from antimicrobial use.

Changements dans la sensibilité phénotypique des isolats de Mannheimia haemolytica aux a ntibiotiques de la classe des macrolides au début de la période d'alimentation après l'utilisation m étaphylactique de tulathromycine chez les veaux des parcs d'engraissement de l'Ouest canadien. Les bovins à risque élevé de maladies respiratoires bovines à leur entrée dans les parcs d'engraissement de l'Ouest canadien sont souvent traités métaphylactiquement avec des antimicrobiens de la classe des macrolides. Des taux élevés de résistance aux macrolides ont été signalés chez les isolats de Mannheimia haemolytica provenant d'échantillons cliniques, mais il est moins clair si cette tendance s'étend à la population plus large des parcs d'engraissement. L'objectif était de décrire les changements à court terme [< 40 jours d'alimentation (DOF)] dans la récupération et la sensibilité des isolats de M. haemolytica provenant de veaux sains en parc d'engraissement après une exposition métaphylactique à la tulathromycine. Huit cohortes de 100 veaux (n = 800) ont été échantillonnées via un prélèvement nasopharyngé profond lors du traitement d'entrée (i.e., avant la métaphylaxie, à 1 DOF) et à nouveau à 13 DOF. Dix veaux de chaque cohorte (n = 80) ont été échantillonnés au hasard une troisième fois à 36 DOF. La récupération des isolats de M. haemolytica dans toutes les cohortes a augmenté au cours de la période d'étude, passant de 33 % (IC 95 % : 26,5 à 40,2 %) à 1 DOF à 75 % (IC 95 % : 71,4 à 78,3 %) à 36 DOF. Un changement significatif dans la distribution de la concentration minimale inhibitrice (MIC) de la tulathromycine de 1 DOF (MIC90 ≤ 8 µg/mL) à 13 DOF (MIC90 > 64 µg/mL) a été observé. Un sous-ensemble de 36 isolats de 13 DOF criblés pour les gènes de résistance aux macrolides via une réaction d'amplification en chaîne par polymérase multiplex hébergeaient tous les gènes msrE et mphE. L'isolement de M. haemolytica à 13 et 36 DOF n'a pas diminué en réponse à l'utilisation métaphylactique de la tulathromycine; à l'inverse, nous avons suggéré le potentiel de propagation rapide entre les enclos d'un clone résistant aux macrolides par 13 DOF dans 6 des 8 enclos sous la pression sélective de l'utilisation d'antimicrobiens.(Traduit par Dr Serge Messier).

X-ray tube operators can be exposed to equal or higher scattered radiation doses to the hand as cassette holders during diagnostic radiographic procedures of the equine vertebral column and limbs.

OBJECTIVE: The objectives of this study were to investigate scattered radiation doses to the hands of equine workers holding the cassette and the x-ray tube by hand, for both limb and vertebral column studies, and to compare the scattered radiation attenuation of lead with radiation protection lead-free gloves. Radiation doses to the hands of the cassette holder in the primary beam were also investigated. SAMPLE: A whole-body horse cadaver. PROCEDURES: A portable x-ray unit was used to simulate 6 radiographic study types in the horse cadaver. Doses were measured with no shielding and, for cassette holders, with the ion chamber enclosed in a lead glove and a lead-free glove. Thirty exposures were performed for each study view and condition (n = 1,920). RESULTS: Mean scattered doses to x-ray unit operators were higher than doses to cassette holders for ungula (hoof), thoracic vertebrae, and lumbar vertebrae studies, whereas doses to cassette holders were higher than doses to x-ray tube operators for studies of the metacarpophalangeal joint (fetlock) and tarsus (hock). Doses did not differ for the stifle joint. Mean percentage decrease in scattered radiation dose was 99.58% with lead gloves and 98.9% with lead-free gloves. CLINICAL RELEVANCE: X-ray tube operators can be exposed to equal or higher scattered radiation doses to the hand as cassette holders. Lead-free hand shielding should only be considered as an alternative to lead gloves if their lighter weight increases frequency of use by workers.

Antimicrobial resistance in bovine respiratory disease: Auction market- and ranch-raised calves.

This study compared changes in prevalence and antimicrobial susceptibility of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni in feedlot calves derived from the auction market (AUCT; n = 299) and from a single-ranch source (RANCH; n = 300). In the AUCT calves, the prevalence of Mannheimia haemolytica decreased, whereas Histophilus somni increased over the feeding period. The AUCT calves showed an increase in isolates not susceptible to tulathromycin for all bovine respiratory disease (BRD) pathogens, an increase in Pasteurella multocida and Histophilus somni isolates not susceptible to oxytetracycline, and an increase in Pasteurella multocida isolates not susceptible to florfenicol. In the RANCH calves, the prevalence of all 3 BRD pathogens was high at feedlot entry and decreased significantly during the study period. In RANCH calves, there was a significant increase in Pasteurella multocida isolates not susceptible to oxytetracycline, tulathromycin, and florfenicol. Surprisingly, there was a significant decrease in Mannheimia haemolytica isolates that were not susceptible to oxytetracycline, tilmicosin, and tulathromycin.

Résistance aux antimicrobiens lors de maladies respiratoires bovines : veaux provenant de marché aux enchères et ceux élevés en ranch. Cette étude a comparé les changements dans la prévalence et la sensibilité aux antimicrobiens de Mannheimia haemolytica, Pasteurella multocida et Histophilus somni isolés de veaux en parc d'engraissement provenant du marché aux enchères (AUCT; n = 299) et d'un seul ranch (RANCH; n = 300). Chez les veaux AUCT, la prévalence de M. haemolytica a diminué, tandis que celle d'H. somni a augmenté au cours de la période d'alimentation. Les veaux AUCT ont montré une augmentation des isolats non sensibles à la tulathromycine pour tous les agents pathogènes des maladies respiratoires bovines (BRD), une augmentation des isolats de P. multocida et H. somni non sensibles à l'oxytétracycline, et une augmentation des isolats de P. multocida non sensibles au florfénicol. Chez les veaux du RANCH, la prévalence des 3 agents pathogènes BRD était élevée à l'entrée du parc d'engraissement et a diminué de manière significative au cours de la période d'étude. Chez les veaux RANCH, il y a eu une augmentation significative des isolats de P. multocida non sensibles à l'oxytétracycline, à la tulathromycine et au florfénicol. Étonnamment, il y a eu une diminution significative des isolats de M. haemolytica qui n'étaient pas sensibles à l'oxytétracycline, à la tilmicosine et à la tulathromycine.(Traduit par Dr Serge Messier).

Workers should take steps to mitigate surface lead exposure when using lead-containing personal protective equipment.

Veterinary workers use lead shielding for protection against harm from ionizing radiation during diagnostic imaging. Surface lead on shielding has been reported as a potential exposure hazard. The purpose of this prospective, analytical, descriptive study was to measure surface lead on lead-containing shielding in the field service and small animal radiology areas of a veterinary teaching hospital, and to examine potential risk factors for surface lead. Surface lead on a convenience sample of 54 lead shielding items was measured in a commercial laboratory using inductively coupled plasma mass spectrometry. The median and range of surface lead for aprons, thyroid collars, and gloves were 3.6 µg/dm2 (range, 1.3-22.4 µg/dm2 ), 23.1 µg/dm2 (range, 2.6-116 µg/dm2 ), and 134 µg/dm2 (range, 1.5-155 µg/dm2 ), respectively. In the final multivariable analysis, the mean surface lead on thyroid collars and gloves was higher than on aprons (relative differences 4.8, 95% confidence interval [CI] 2.2, 10.5, P < 0.001; and 9.5, 95% CI 4.4, 20.6, P < 0.001, respectively). The mean surface lead on shielding in the worst condition was higher than on shielding in the intermediate and best conditions (P < 0.001). Lead shielding provides effective protection against the harmful effects of ionizing radiation, and shielding should always be worn during radiation exposure. Based on our findings and the common use of lead shielding in veterinary workplaces, we recommend that employers inform workers of this hazard and provide training on steps to mitigate exposure, including the use of disposable gloves when wearing lead shielding and handwashing after use.

Survey of self-reported radiation safety practices among North American veterinary technicians involved in equine radiography using portable x-ray equipment.

OBJECTIVES: To describe self-reported radiation safety practices by equine veterinary technicians in North America and identify factors associated with these practices. SAMPLE: 154 equine technicians. PROCEDURES: An electronic questionnaire regarding radiation safety practices during the use of portable x-ray equipment was sent to 884 members of the American Association of Equine Veterinary Technicians and Assistants. Data were summarized, and various factors were evaluated for associations with reported safety practices. RESULTS: 221 of 884 (25.0%) questionnaires were completed, including 154 by equine technicians who had been involved in equine radiography as x-ray tube operators, cassette holders, or both in the previous year. Lead apron use was suboptimal, reported as "always" for 80.0% (104/130) of tube operators and 83.1% (123/148) of cassette holders. Approximately 20% of participants never wore thyroid shields, and approximately 90% never wore lead eyeglasses. Almost 50% of participants did not have lead eyeglasses available. Although > 55% of participants always held the x-ray equipment by hand, 58.4% (73/125) of tube operators and 25.0% (35/140) of cassette holders never wore gloves. Cassette holders wore lead gloves and personal radiation dose-monitoring devices significantly more frequently than did tube operators. CONCLUSIONS AND CLINICAL RELEVANCE: Compliance of North American equine technicians with radiation safety recommendations by the National Council on Radiation Protection and Measurements was suboptimal. Improvements in radiation safety training and education, strengthening the connection between academic institutions and private practices, and greater availability and requirement of personal protective equipment use by senior clinicians and employers might aid in improving safety practices.

Self-reported radiation safety behaviors among veterinary specialists and residents performing fluoroscopic procedures on small animals.

OBJECTIVE: To describe the radiation safety behaviors of veterinary specialists performing small animal fluoroscopic procedures and examine potential risk factors for these behaviors, including knowledge of radiation risk and training regarding machine operating parameters. SAMPLE: 197 veterinary specialists and residents in training. PROCEDURES: An electronic questionnaire was distributed to members of the American Colleges of Veterinary Internal Medicine (subspecialties of cardiology and small animal internal medicine), Veterinary Radiology, and Veterinary Surgery. RESULTS: The overall survey response rate was 6% (240/4,274 email recipients). Of the 240 respondents, 197 (82%) had operated an x-ray unit for a small animal fluoroscopic procedure in the preceding year and fully completed the questionnaire. More than 95% of respondents believed that radiation causes cancer, yet approximately 60% of respondents never wore hand or eye protection during fluoroscopic procedures, and 28% never adjusted the fluoroscopy machine operating parameters for the purpose of reducing their radiation dose. The most common reasons for not wearing eye shielding included no requirement to wear eyeglasses, poor fit, discomfort, and interference of eyeglasses with task performance. Respondents who had received training regarding machine operating parameters adjusted those parameters to reduce their radiation dose during procedures significantly more frequently than did respondents who had not received training. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the self-reported suboptimal radiation safety practices among veterinary fluoroscopy users, we recommend formal incorporation of radiation safety education into residency training programs. All fluoroscopy machine operators should be trained regarding the machine operating parameters that can be adjusted to reduce occupational radiation exposure.

Biosecurity practices in western Canadian cow-calf herds and their association with animal health.

Biosecurity practices of beef cow-calf herds in western Canada have not been studied extensively nor is there a good understanding of their association with herd health. A survey was sent to 103 cow-calf producers of the Western Canadian Cow-Calf Surveillance Network. Eighty completed questionnaires were returned. Bulls were purchased for all herds during the 2014 to 2017 study period; 54% of herds purchased heifers and 42% purchased cows. The use of standard biosecurity practices was generally low with 30% of producers keeping purchased animals separate and 30% vaccinating new additions. None of the evaluated biosecurity practices were associated with reporting Johne's disease. The purchase of > 10 bulls, the purchase of cows, not vaccinating animals bought into the herd, and use of community pasture were associated with a bovine respiratory disease outbreak. Outbreaks of calf diarrhea were associated with the purchase of 10 or more bulls, the use of a community pasture, and leasing or sharing bulls.

Pratiques de biosécurité dans les troupeaux de vaches-veaux de l'Ouest canadien et leur association avec la santé animale. Les pratiques de biosécurité des troupeaux de bovins de boucherie de l'Ouest canadien n'ont pas fait l'objet d'études approfondies et il n'y a pas de bonne compréhension de leur association avec la santé du troupeau. Un sondage a été envoyé à 103 producteurs de vaches-veaux du Réseau de surveillance vache-veau de l'Ouest canadien. Quatre-vingts questionnaires remplis ont été retournés. Des taureaux ont été achetés pour tous les troupeaux au cours de la période d'étude 2014 à 2017; 54 % des troupeaux ont acheté des génisses et 42 % des vaches. L'utilisation des pratiques de biosécurité standard était généralement faible, 30 % des producteurs gardant les animaux achetés séparés et 30 % vaccinant les nouveaux ajouts. Aucune des pratiques de biosécurité évaluées n'était associée à la déclaration de la maladie de Johne. L'achat de plus de 10 taureaux, l'achat de vaches, et la non-vaccination d'animaux incorporés dans le troupeau, et l'utilisation de pâturages communautaires ont été associés à une épidémie de maladie respiratoire bovine. Les flambées de diarrhée des veaux étaient associées à l'achat de 10 taureaux ou plus, à l'utilisation d'un pâturage communautaire et à la location ou au partage de taureaux.(Traduit par Dr Serge Messier).