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.

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.

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.

Incidence and Risks of HIV Infection, Medication Options, and Adverse Effects in Accidental Needle Stick Injuries: A Narrative Review

Accidental needle sticks can lead to infections, including HIV. As scientists have learned more about HIV and its replicative physiology, identification of target sites and novel medications have been developed. HIV is spread throughout the population through contact with blood, semen, and rectal or vaginal secretions of infected individuals. Therefore, it is important in general for healthcare workers to be aware of its transmission modes and ways to minimize exposure. In this regard, even with hospitals providing education, training, and safety protocols, there is a continued infection spread with HIV, especially by accidental needle sticks. There is also a wide variety of testing that can be used for HIV utilizing different methodologies, allowing for improved measurement of infection status. Any person with HIV should be tested to clarify infection status and be educated to minimize future virus spread. The current CDC recommendations for HIV infection treatment are antiretroviral therapies, such as an HIV postexposure prophylaxis regimen, which consists of a cocktail of antiretrovirals and postexposure prophylaxis immediately for occupational exposures, such as accidental needlestick exposure from an HIV infected patient. To decrease accidental HIV stick injuries, there are safety precautions in place, that if followed, would help reduce this incidence. HIV accidental needle stick injuries still happen in the hospital workplace, but with proper education and treatment, if exposed, there is hope to minimize the effects.

Pharmacological Approaches in Managing Symptomatic Relief of Benign Prostatic Hyperplasia: A Comprehensive Review

Benign Prostatic Hyperplasia (BPH) is a prevalent condition that affects aging men, leading to the development of lower urinary tract symptoms (LUTS) and potentially severe complications such as complete obstruction. The management of BPH typically involves the use of medications from different classes, including alpha-1 antagonists, 5-alpha reductase inhibitors, and anticholinergics. Combination therapy utilizing drugs from different classes can also effectively manage the BPH-LUTS complex. Recent research has revealed that phosphodiesterase 5 (PDE5) inhibitors, including Tadalafil and Sildenafil, are highly effective in treating LUTS associated with BPH. Tadalafil as a monotherapy has recently been shown to significantly improve LUTS in BPH patients. Additionally, the use of herbal remedies as a treatment option for BPH has also been widely debated. Previous research suggests that saw palmetto can reduce BPH symptoms through several proposed mechanisms, but recent trials have found inconsistencies in its efficacy. In this literature review, we conducted an extensive PubMed database search to provide current and comprehensive insights into BPH treatment options. This review comprehensively evaluates available treatments for managing BPH, highlighting the effectiveness of different classes of medications and combination therapies in managing associated symptoms. The present investigation also discusses recent research on the efficacy of PDE5 inhibitors in treating LUTS associated with BPH and the uncertain efficacy of herbal remedies. The insights provided by this study can guide healthcare professionals in making informed decisions about managing BPH, ultimately improving patient outcomes.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 1: Risk factors

Maternal antibodies, delivered to the calf via colostrum, are crucial to prevent calfhood diseases and death. However, knowledge regarding the factors influencing this transfer of total and specific Immunoglobulin G (IgG) against common enteric and respiratory disease pathogens under current production conditions is sparse. The objectives of this study were to determine risk factors influencing total and pathogen-specific immunoglobulin G (IgG) concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus type 1 and 2 (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus type 1 (BHV-1) in the serum of newborn beef calves. A total of 420 serum samples were collected from 1- to 7-day-old beef calves born on 6 farms in Alberta, Canada. Samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against E. coli, BRoV, C. parvum, BVDV, PI-3, BRSV, and BHV-1. Multivariable multilevel linear and logistic regression models were built to evaluate dam- and calf-level risk factors associated with total and pathogen-specific IgG concentrations, failed transfer of passive immunity (FTPI; serum IgG < 10 g/L), and inadequate transfer of passive immunity (ITPI; serum IgG < 24 g/L). Farm was included as a random effect in all models to account for clustering at the herd level. Of the 420 calves included in this study, 5% (n = 20) and 18% (n = 75) of calves had FTPI and ITPI, respectively. Receiving colostrum intervention (i.e., being fed colostrum or colostrum product by either bottle or tube) was the most consistent risk factor for low total IgG concentration and significantly increased the odds of FTPI (Odds ratio (OR): 6.1, 95% CI: 2.0-18.9) and ITPI (OR: 4.8, 95% CI: 2.1-10.8). Calves born to cows consistently had higher pathogen-specific IgG concentrations (P < 0.0001), compared to calves born from heifers, and calves born to vaccinated dams had significantly higher BRoV, BVDV, and BHV-1-specific IgG concentrations. Interestingly, E.coli-specific IgG concentrations were associated with dam vaccination only in cows but not in heifers, which was likely due to differing vaccination strategies used. This study highlights the need to review and refine protocols with respect to dam vaccination and colostrum intervention on cow-calf operations.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 2: Associations with health and growth

The association of poor transfer of passive immunity (TPI) with negative health outcomes is extensively researched in dairy calves. However, few field studies have examined the effect of total and particularly pathogen-specific Immunoglobulin G (IgG) concentrations on pre-weaning health and growth of beef calves. Hence, the objective of this study was to determine the association of total and pathogen-specific IgG concentrations against selected pathogens associated with neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) and the odds of pre-weaning treatments, mortality, and the growth of newborn beef calves. A total of 420 serum samples from 1- to 7-day old beef calves born on 6 farms in Alberta, Canada, were available for this observational study. Serum samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus Type 1 (BHV-1). Data about the individual dam- and calf-level risk factors, calf treatments, mortality, and birth and weaning weights were collected. Multivariable multilevel logistic and linear regression models were built to evaluate the association of total and pathogen-specific IgG concentrations with the odds of mortality and average daily gain (ADG), respectively, while their association with the odds of pre-weaning treatment was established by univariable logistic regression analysis. The odds of calves with IgG concentrations < 10 g/L of getting treated (OR 7.9, 95 % CI 2.7-23.7) and dying (OR: 18.5, 95 % CI: 3.7-93.4) were higher than for their counterparts (P < 0.0001). Calves with IgG concentrations < 24 g/L also had higher odds of dying (OR: 10.1, 95 % CI: 2.6-40.2) and had lower ADG (-0.09 kg, SE: 0.03, P < 0.002) than calves with IgG concentrations ≥ 24 g/L. Higher BVDV-specific IgG concentration was protective against mortality (OR: 0.97, 95 % CI: 0.96-0.99, P < 0.001). This study highlights the negative association of inadequate TPI with health and growth of beef calves and thus, the need to refine protocols for dam vaccination and colostrum intervention in cow-calf operations to meet these higher IgG targets.

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.

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.

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.

Integration of ITS-2 rDNA nemabiome metabarcoding with Fecal Egg Count Reduction Testing (FECRT) reveals ivermectin resistance in multiple gastrointestinal nematode species, including hypobiotic Ostertagia ostertagi, in western Canadian beef cattle

A large-scale Fecal Egg Count Reduction Test (FECRT) was integrated with ITS-2 rDNA nemabiome metabarcoding to investigate anthelmintic resistance in gastrointestinal nematode (GIN) parasites in western Canadian beef cattle. The study was designed to detect anthelmintic resistance with the low fecal egg counts that typically occur in cattle in northern temperate regions. Two hundred and thirty-four auction market-derived, fall-weaned steer calves coming off pasture were randomized into three groups in feedlot pens: an untreated control group, an injectable ivermectin treatment group, and an injectable ivermectin/oral fenbendazole combination treatment group. Each group was divided into six replicate pens with 13 calves per pen. Individual fecal samples were taken pre-treatment, day 14 post-treatment, and at monthly intervals for six months for strongyle egg counting and metabarcoding. Ivermectin treatment resulted in an 82.4% mean strongyle-type fecal egg count reduction (95% CI 67.8-90.4) at 14 days post-treatment, while the combination treatment was 100% effective, confirming the existence of ivermectin-resistant GIN. Nemabiome metabarcoding of third-stage larvae from coprocultures revealed an increase in the relative abundance of Cooperia oncophora, Cooperia punctata, and Haemonchus placei at 14 days post-ivermectin treatment indicating ivermectin resistance in adult worms. In contrast, Ostertagia ostertagi third-stage larvae were almost completely absent from day 14 coprocultures, indicating that adult worms of this species were not ivermectin resistant. However, there was a recrudescence of O. ostertagi third stage larvae in coprocultures at three to six months post-ivermectin treatment, which indicated ivermectin resistance in hypobiotic larvae. The calves were recruited from the auction market and, therefore, derived from multiple sources in western Canada, suggesting that ivermectin-resistant parasites, including hypobiotic O. ostertagi larvae, are likely widespread in western Canadian beef herds. This work demonstrates the value of integrating ITS-2 rDNA metabarcoding with the FECRT to enhance anthelmintic resistance detection and provide GIN species- and stage-specific information.

Effects of naturally acquired gastrointestinal nematode infection on bovine viral diarrhea virus vaccine-directed antibody response in western Canadian feedlot cattle

Objective

To determine how gastrointestinal nematode (GIN) infection, reflected by fecal egg counts and Ostertagia ostertagi serum antibody titers, is associated with the antibody response to bovine viral diarrhea virus type 1 (BVDV-1) vaccine antigen in fall-weaned feedlot cattle from western Canada.

Animals

Cross-sectional study with 240 steer calves derived from an auction market.

Procedure

At feedlot arrival, calves were given a commercial vaccine containing modified live BVDV-1. Serum neutralization antibody titers against BVDV-1 antigens were determined in individual blood samples collected pre-vaccination and 21 d after vaccination. A modified Wisconsin sugar floatation method was used to obtain individual calf GIN egg counts in fecal samples on arrival. Antibody titers against O. ostertagi were determined using an enzyme-linked immunosorbent assay in on-arrival blood samples.

Results

Fecal egg counts and O. ostertagi titers were not associated with vaccine antibody-fold changes. Similarly, fecal egg counts and O. ostertagi titers were not associated with vaccine-induced seroconversion.

Conclusions

The relatively low GIN burdens, reflected by the overall low fecal egg counts in these fall-weaned feedlot calves, did not have measurable adverse effects on the humoral immune response to BVDV-1 vaccine antigens.

Clinical relevance

An adequate response to vaccination is important for cattle welfare and productivity. Conditions that negatively affect this response may vary regionally, such as GIN infection. Understanding this is essential. Although subclinical intestinal parasitism did not noticeably affect the antibody response in these steers, higher GIN burdens and actual immune protection from clinical disease remain to be investigated.

148 Effect of Increasing Sodium Sulfate in Water on Intake on Ruminal Fermentation and the in Vitro Effect of Bismuth Subsalicylate on gas Production and NDF Digestibility

This study evaluated in vivo effects of increasing sulfate concentrations of drinking water on dry matter intake (DMI), water intake, ruminal fermentation, and apparent total-tract digestibility, and in vitro effects of water sulfate and bismuth subsalicylate (BSS) dose. Eight ruminal-cannulated beef heifers (382 ± 45 kg) were stratified into two complete and one incomplete 3×3 Latin squares with 28 d periods. Water contained 341 ± 29 (LS), 2,785 ± 71 (MS), or 4,948 ± 163 mg/L (HS) sulfate. Feed and water intake, ruminal fermentation, and nutrient digestibility were evaluated. Ruminal gas samples were collected every 4 h on d 27 to analyze hydrogen sulfide (H2S) concentration. At the end of each period, digesta collected from heifers in the complete Latin squares were used for in vitro incubation to evaluate water sulfate and BSS dose (0.0, 0.2, 0.4, and 0.6% dry matter). Water intake was 7 L/d greater (P &lt; 0.01) for HS than LS, while MS did not differ. Water sulfate did not affect DMI, but total sulfur intake increased with increasing water sulfate concentration (P &lt; 0.01). Heifers drinking MS and HS had greater ruminal H2S for 10.5 h after water provision and HS continued to be greater for another 4 h relative to LS (sulfate hour, P &lt; 0.01). Ruminal SCFA concentration, molar proportions of major acids, and nutrient digestibility were not affected (P≥0.19). There were no interactions between water sulfate and BSS in vitro. In vitro H2S production (µg/48 h) increased with increasing sulfate concentration (P &lt; 0.01) and was reduced (P=0.05) by BSS inclusion. Neutral detergent fiber digestibility was not affected by sulfate or BSS. Increasing water sulfate concentrations did not negatively affect water or feed intake but did increase H2S concentration and production in vivo and in vitro, respectively. Bismuth subsalicylate may be a potential strategy to reduce H2S production.

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.

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.

Interventions to reduce losses in the cascade of care for latent tuberculosis: a systematic review and meta-analysis

BACKGROUND: Losses can occur throughout the latent tuberculosis infection (LTBI) cascade of care. This can result in suboptimal rates of effective treatment for LTBI. We conducted a systematic review and meta-analysis to estimate the effect of different interventions to reduce losses in the LTBI cascade before treatment completion.METHODS: We searched several databases for articles reporting outcomes for interventions designed to strengthen the LTBI cascade. We included papers published in English from January 1990 until February 2018. Where possible, estimates were pooled using random-effects meta-analysis.RESULTS: We identified 30 studies that evaluated 32 different interventions aimed at reducing losses in the LTBI cascade. In pooled analysis, interventions that improved completion of cascade steps included patient incentives (respectively 42 [95% CI 34-51] and 48 [95% CI 15-81] additional patients completing initial assessment and medical evaluation per 100 starting); health care worker education (28 [95% CI 4-52] additional patients initiating initial assessment per 100 identified; home visits (additional 13 [95% CI 4-21] patients completing initial assessment per 100 starting); digital solutions (additional 11 [95% CI 4-21] patients initiating initial assessment per 100 identified); and patient reminders (additional 7 [95% CI 0.3-13] patients completing initial assessment per 100 starting). Several other interventions reduced losses at specific cascade steps, but evidence for these interventions came from single studies and could not be pooled.CONCLUSIONS: Although there is limited evidence that any single intervention significantly improves the LTBI cascade, many studies provide information about effective ways to strengthen it.

Gastrointestinal nematode prevalence and fecal egg counts in beef cattle from western Canada

Fecal samples were collected from cows (n = 1458), calves (n = 1188), and replacement heifers (n = 921) between 2012 and 2014 from 199 herds and generalized estimating equations were used to predict mean fecal egg counts and prevalence of egg-positive samples. Replacement heifers had the highest prevalence of Trichostrongylid-type eggs at 83% [95% confidence interval (CI): 78% to 87%], and cows had the lowest at 75% (95% C: 70% to 81%). Nematodirus spp. was most frequently present in calves [predicted prevalence: 34% (95% CI: 28% to 40%)]. Mean fecal egg counts were highest in calves with 5.9 (95% CI: 3.9 to 7.8) Trichostrongylid-type eggs per gram (EPG) of feces and 1.0 (95% CI: 0.7 to 1.4) Nematodirus spp. EPG. Although mean egg counts were low to moderate, the high prevalence highlights the need to further investigate the epidemiology of gastrointestinal nematodes in western Canada. This is particularly relevant considering management changes, increasing herd sizes, climate change, and threatening anthelmintic resistance.

Gastrointestinal nematode management in western Canadian cow-calf herds

There is a paucity of information from western Canadian beef cow-calf producers about how they control gastrointestinal nematodes. The objectives of this study were to describe cow-calf producers' management practices related to control of gastrointestinal nematodes including pasture management and use of parasite control products. A questionnaire was distributed to 105 producers in May 2015. Responses from 97 producers revealed the almost uniform dependence on the use of a pour-on macrocyclic lactone parasite control product in the fall as part of a routine farm management program. Control of external parasites was the primary reason for treatment, while none of the producers chose to treat specifically to manage internal parasites. The predominant management practices identified through this study increase the risk of development of anthelmintic resistance. The results also highlight the need to raise awareness of the importance of an evidence-based gastrointestinal nematode control program in beef cow-calf herds.

Examining Procedural Unfairness and Credibility Findings in the UK Asylum System

This article addresses a key problem confronted by immigration judges (IJs) in their assessment of the asylum claims of unaccompanied asylum-seeking children – who are often not allowed to speak or participate in their own hearings – namely the manner in which asylum legal procedure is intertwined with an IJ’s decision to refuse the claim on the basis of adverse credibility. This article has three linked aims: to examine research that looks at how IJs decide credibility; to set out an ethnographic approach to better understand IJs’ decision-making; and to argue that asylum tribunals need to adopt appropriate guidelines.

85 DNA parentage in multi-sire breeding groups and sire repeatability on replacement heifer performance

The objective of this study was to apply DNA parentage testing in multi-sire breeding groups to assess repeatability of a sire’s impact on replacement females and terminal animals. Parentage testing was performed on DNA from 37 bulls and 1578 calves from a commercial ranch using natural breeding in four multi-sire breeding pastures over a four-year period (2015–2018). Parentage data was analyzed using Chi-square procedures. In 2016 and 2018, all bulls in the four breeding groups sired significantly different (P &lt; 0.01) numbers of calves than expected. In 2015 and 2017, bulls in 2 of 4 and 3 of 4 breeding groups, respectively, sired significantly different (P &lt; 0.01) numbers of calves than expected. For the 2015 and 2016 calf crops, three of 24 bulls used sired 30% of the calves and 33% of the selected replacement heifers. In 2017 and 2018, the calves born to the daughters of these three most prolific sires, averaged 4.5kg lower weaning weights than the average wean weights of the remaining calves. In 2018, all calves were tested for breed composition and vigour score using the EnvigourHX test from Neogen (Neogen Canada Inc., Edmonton Alberta, Canada). The average herd vigour score was 70%; the average vigour score for 2018 calves born to daughters of the top three prolific sires was 56%. Coupling production measures (weaning weights, birth dates, calving intervals) with sire parentage and vigour score data provides beef cattle producers with additional information to guide breeding choices to improve production in their operations.

Clinical impacts of administering a nonsteroidal anti-inflammatory drug to beef calves after assisted calving on pain and inflammation, passive immunity, health, and growth

Assisted calves are often born weak, injured, or oxygen deprived and have a higher risk of morbidity and mortality. The objective was to investigate the impact of using pain mitigation at birth in assisted beef calves on physiological indicators of pain and inflammation, passive immunity, health, and growth. Thirty-three primiparous cows and their calves requiring assistance at birth on two ranches located in southern Alberta were enrolled. Data collected at birth include date and time of calving, calf sex, meconium staining, presentation of calf, and calving difficulty (easy assist: one person manually delivered the calf; difficult assist: delivery by two or more people, or mechanical assistance). Within 10 min of birth, calves were stratified by calving difficulty, randomized to a medication group, and received a subcutaneous dose of meloxicam (0.5 mg/kg BW) or an equivalent volume of placebo. Cow–calf pairs were then placed in individual box stalls for observation and sampling. At birth, 1, 4, and 24 h after birth, heart rate, respiratory rate, and rectal temperature were assessed and blood samples collected to measure indicators of pain and inflammation (cortisol, corticosterone, substance P, and haptoglobin). Serum IgG concentration and failed transfer of passive immunity (serum IgG concentration <24 g/L) were assessed in the 24-h blood samples. Preweaning treatment for disease and mortality information was collected and calves were weighed at 7 to 10 d of age and at weaning. Of the 33 calves enrolled, 17 calves received meloxicam and 16 calves received a placebo. Meloxicam-medicated calves had significantly greater ADG to 7 to 10 d of age (P = 0.05) (mean = 0.9 kg/d; SE = 0.10) compared with placebo-medicated calves (mean = 0.6 kg/d; SE = 0.12). There was no significant effect of meloxicam on physiological indicators of pain and inflammation, standing or nursing by 1 h, passive immunity, health outcomes, or ADG to weaning (P > 0.1). Although this was a small sample population, meloxicam given to assisted calves at birth improved ADG in the first week of life, which may indicate an important production management tool for improving well-being in assisted calves.

Identifying performance benchmarks and determinants for reproductive performance and calf survival using a longitudinal field study of cow-calf herds in western Canada

The cow-calf industry in North America is in a period of rapid consolidation with corresponding increases in herd sizes and changes in management. The objectives of this study were to examine longitudinal data on reproductive performance in cow-calf herds and identify benchmarks for the most critical measures and important sources of differences among herds. To address these questions, a surveillance network was established in western Canada to collect data between 2013 to 2017 privately owned cow-calf herds during calving (n = 105 herds) and at pregnancy testing (n = 94 herds). Data were summarized for a number of indices of herd performance. However, the values considered to be most reliable and accurate were the percentage of females not pregnant when tested by a veterinarian, the percentage of calves dead within 24 hours of birth, and the percentage of calves dead from 24 hours to weaning. The mean and variation between herds for heifers, measured using standard deviation, was greater than for cows for: non-pregnancy (cows 6.8% (mean)±3.4%(SD), heifers 9.7%±8.2%), calf death from birth to 24 hours (cows 2.1%±1.6%, heifers 3.6%±4.5%), and calf death from 24 hours to weaning (cows 2.5%±2.4%, heifers 2.9%±3.9%). Benchmarks or performance targets derived from the 25th percentiles of these data for both cows and heifers were <5% for non-pregnancy risk and <1% for calf loss within 24 hours of birth. The suggested benchmark for calf loss from 24 hours to weaning was <2% for cows and <1% for heifers. All outcomes consistently displayed greater variation between herds as compared to year to year differences within herds with the exception of calf loss before 24 hours in cows. The timing of the start of breeding season was a consistent source of variation in risks of non-pregnancy and calf losses. Cows bred in April or earlier to start calving in late December or January were at increased risk of low pregnancy percentages (p<0.001) and calf losses at birth (p<0.04), as well as increased calf loss before weaning in both cows and heifers (p<0.02). There was also an increase in the risk of non-pregnancy for cows and heifers (p<0.001) where first exposure to breeding was not until July or August. In contrast, the risks of calf loss within 24 hrs of birth (p<0.001) and from 24 hrs to weaning in cows (p<0.02) first exposed to breeding in July and August were significantly lower than for herds that had earlier breeding seasons.

Benchmarking calving management practices on western Canada cow-calf operations

Benchmarking current calving management practices and herd demographics in the western Canadian cow–calf production system helps to fill the gap in knowledge and understanding of how this production system works. Further investigation into the relationships between management decisions and calf health may guide the development of management practices and protocols to improve calf health, especially in compromised calves after a difficult birth. Therefore, the objectives of this cross-sectional study were to describe current calving management practices on western Canadian cow–calf ranches and to investigate the association of herd demographics with herd-level incidence of calving assistance, morbidity, mortality, and use of calving and colostrum management practices. Cow–calf producers were surveyed in January 2017 regarding herd inventory and management practices during the 2016 calving season. Ninety-seven of 110 producers enrolled in the western Canadian Cow-Calf Surveillance Network responded. Average herd-level incidence of assisted calvings was 4.9% (13.5% heifers, 3.2% cows), stillbirths was 2.1% (3.3% heifers, 1.9% cows), preweaning mortality was 4.5%, and preweaning treatment for disease was 9.4% (3.0% neonatal calf diarrhea, 3.8% bovine respiratory disease, 2.6% other diseases). Greater than 90% of producers assisted calvings and would intervene with colostrum consumption if the calf did not appear to have nursed from its dam. Late calving herds (i.e., started calving in March or later) had significantly lower average herd-level incidence of assistance, treatment for disease, and mortality (P < 0.05). In earlier calving herds (i.e., started calving in January or February) producers had shorter intervals between checking on dams for signs of calving or intervening to assist with a calving (P < 0.05). In early calving herds, producers were more likely to perform hands-on colostrum management techniques such as placing the cow and calf together or feeding stored, frozen colostrum (P < 0.05). There were no associations between herd size and herd-level incidences or management techniques (P > 0.05). This study suggests that in western Canada earlier calving herds are more intensively managed, whereas later calving herds are more extensively managed. Herd demographics may be important to consider when investigating factors associated with management strategies, health, and productivity in cow–calf herds.

Antimicrobial resistance in fecal Escherichia coli and Campylobacter spp. from beef cows in western Canada and associations with herd attributes and antimicrobial use

The objectives of this study were to describe the frequency of antimicrobial resistance (AMR) in Escherichia coli and Campylobacter spp. isolates in fecal samples from beef cow-calf herds and to examine the associations between herd management practices, reported antimicrobial use, and AMR. Baseline prevalence data are needed to evaluate the effectiveness of antimicrobial stewardship programs. A pooled fecal sample, representing 20 cows, was collected from each of 107 herds during pregnancy testing. In the 305 recovered E. coli isolates (maximum 3 per herd), resistance to ≥ 1 antimicrobial was identified in 12 isolates [4%, 95% confidence interval (CI): 2% to 7%] from 105 herds (11%, 95% CI: 7% to 19%). The most common resistances identified in E. coli isolates were to tetracycline (3%) and to both streptomycin and sulfisoxazole (3%). Only 1 E. coli isolate was resistant to an antimicrobial of very high importance to human health - amoxicillin/clavulanic acid. However, 2 E. coli isolates had intermediate susceptibility to ciprofloxacin. Resistance to 1 antimicrobial was identified in 16 of 87 Campylobacter spp. isolates (18%, 95% CI: 11% to 28%) from 87 herds. Resistance to tetracycline was reported in 15% of Campylobacter spp. isolates and to nalidixic acid in 3.4%. Herds in which cows were treated with florfenicol were more likely to have E. coli resistance to ≥ 2 antimicrobials (OR 7.1, 95% CI: 1.1 to 57, P = 0.03). Herds with calf mortality of > 5% were more likely to have E. coli with resistance to streptomycin and sulfisoxazole [odds ratio (OR): 7.8, P = 0.03]. The results of this study are consistent with previous reports from western Canada and provide a starting point for designing an ongoing antimicrobial surveillance program.

Vaccine usage in western Canadian cow-calf herds

The aims of this study were to describe when and how vaccines are administered during the production cycle in cow-calf herds in western Canada, as well as the factors that influence vaccine usage as reported by producers. The most commonly used vaccines were bovine viral diarrhea virus/infectious bovine rhinotracheitis (BVDV/IBR) in adult animals and clostridial vaccines in calves. While there has been improvement in usage of reproductive and respiratory viral vaccines since previous studies, there are still several areas in which uptake could be improved. Only 72% of herd owners vaccinated their bulls for at least 1 disease. Not all producers are vaccinating their calves for clostridial diseases, and 15% of producers did not vaccinate their calves for respiratory disease before weaning. One goal of increasing vaccine use is to obtain better infection prevention and control and decrease antimicrobial use in cow-calf herds. Two areas in which antimicrobials are commonly used, but vaccine uptake is limited, are foot rot in adult cows and diarrhea in calves.

Attitudes towards antimicrobial use and factors associated with antimicrobial use in western Canadian cow-calf herds

One hundred cow-calf producers in western Canada were surveyed to determine their perceptions regarding antimicrobial use (AMU) and how these perceptions and other herd management factors were associated with AMU. Veterinarians were the most important source of AMU information. Half of the producers considered antimicrobial resistance (AMR) when choosing antimicrobials, while 24% considered the influence of AMU on AMR in human health. Younger producers < 30 y were most likely to consider AMR when choosing antimicrobials. Injectable products were used for disease prevention in 17% of herds; 5% used medically important antimicrobials in feed and 6% in water. Use of injectable antimicrobials of very high importance to human health was reported in 34% of herds. Producers with higher calf mortality were more likely to report AMU in feed or water. The use of Health Canada Category I antimicrobials was most common when calves were retained after weaning.

Antimicrobial usage in western Canadian cow-calf herds

While ongoing surveillance and research initiatives have provided some information on antimicrobial use (AMU) in many livestock commodities, there are no recent reports for Canadian cow-calf herds. Antimicrobial use data were collected in 2014 for bulls, cows, and calves from 100 herds participating in the Western Canadian Cow-Calf Surveillance Network. Lameness was the most common reason for treatment in cows and bulls, with oxytetracycline being the treatment of choice. Herd owners were most likely to treat calves before weaning with florfenicol, oxytetracycline, and sulfamethazine for respiratory disease or diarrhea. The most frequently reported reason for antimicrobial use in weaned calves was respiratory disease and the most reported product was florfenicol. While 98% of herds reported treating ≥ 1 animal with antimicrobials, most cattle did not receive antimicrobials for either treatment or disease prevention on participating cow-calf operations.

Quantifying subclinical trauma associated with calving difficulty, vigour, and passive immunity in newborn beef calves

This cross-sectional study quantifies subclinical trauma associated with calving difficulty, calf vigour, and passive immunity (PI) in newborn beef calves. The degree of calving difficulty was categorised as: unassisted, easy assist (one or two people manually pulling to deliver the calf) and difficult assist (more than two people pulling, a fetal extractor (ie, calf jack), or caesarean section). Vigour assessment occurred at 10 minutes and blood sampling at 24 hours after birth in 77 beef calves. The measured blood parameters associated with trauma were creatine kinase (CK), aspartate aminotransferase (AST), and haptoglobin. Serum IgG concentration was measured, and an IgG concentration at least 24 g/l was considered as adequate PI. Calving difficulty was associated with elevated levels of CK (P=0.002) and AST (P=0.01), weak suckle reflex (P=0.001), abnormal mucous membrane colour (P<0.0001), and decreased odds of adequate PI (P=0.004). Elevated levels of CK and AST were associated with abnormal mucous membrane colour, incomplete tongue withdrawal and weak suckle reflex at birth (P<0.001). An incomplete tongue withdrawal (P=0.005) and weak suckle reflex (P=0.02) were associated with decreased IgG concentrations. Abnormal mucous membrane colour, incomplete tongue withdrawal, and a weak suckle reflex were associated with decreased odds of having adequate PI (P<0.05). Haptoglobin was not associated with any of the parameters measured. Subclinical trauma was associated with calving difficulty, decreased vigour and decreased odds of having adequate PI. Understanding the impacts of a traumatic birth may aid the development of management strategies for compromised newborn beef calves.

Latent tuberculosis diagnostic tests to predict longitudinal tuberculosis during dialysis: a meta-analysis

SETTING

Tuberculosis (TB) rates in dialysis patients are more than 10 times greater than in the general population. Recent recommendations advise the use of interferon-gamma release assays (IGRAs) over the tuberculin skin test (TST) to aid in the diagnosis of latent tuberculous infection (LTBI); however, their longitudinal predictive ability for TB development has not been assessed.

OBJECTIVE

To determine whether the TST or IGRA are able to predict longitudinal TB development in dialysis patients.

DESIGN

We performed a systematic review to determine the longitudinal risk of TB in dialysis patients. Random-effects meta-analysis was used to determine the incidence rate ratio (IRR) of longitudinal TB development and the predictive value of such tests.

RESULTS

Eight studies were included. An IRR of 2.59 (95%CI 1.20-5.57) for longitudinal TB was seen in patients with a TST ⩾ 10 mm compared to patients with a TST < 10 mm. The positive predictive value (PPV) of a TST ⩾ 10 mm was 11.93% and the negative predictive value was 94.03%. We were unable to analyse the studies that used IGRAs, as only one study had TB events.

CONCLUSION

A TST with a 10 mm cut-off point appears to offer the capability to distinguish long-term risk of TB, with a modest PPV. The predictive value of IGRAs could not be quantified.

Management practices associated with pain in cattle on western Canadian cow-calf operations: A mixed methods study

The implementation of on-farm pain mitigation strategies is dependent on feasibility and importance to producers. Currently, there is a lack of information regarding adoption of management practices associated with pain in cattle within the Canadian beef industry. The objective of this mixed methods study was to describe pain-associated practices implemented on farm and producer perceptions toward pain mitigation strategies. A questionnaire about calving management and calf processing was delivered to 109 cow-calf producers in western Canada. In addition, 15 respondents were purposively selected based on questionnaire responses to participate in individual semistructured, on-farm interviews. The prevalence of pain mitigation strategies used for dystocia and cesarean section by respondents were 46 and 100%, respectively. The majority of operations reported castrating and dehorning calves before 3 mo of age (95 and 89%, respectively). The majority of operations did not use pain mitigation strategies for castration and dehorning (90 and 85%, respectively). Branding was practiced by 57% of respondents, 4% of which used pain mitigation. Thematic content analysis revealed that producers' perception of pain were influenced by what they referred to as "common sense," relatability to cattle, visual evidence of pain, and age of the animal. Factors that influenced participant rationale for the implementation of pain mitigation practices included access to information and resources, age of the animal, benefit to the operation, cost and logistics, market demands, and personal conscience. Overall, management practices were generally in compliance with published Canadian guidelines. Results of this study may provide direction for future policy making, research, and extension efforts to encourage the adoption of pain mitigation strategies.

Management practices associated with stress in cattle on western Canadian cow-calf operations: A mixed methods study

Handling, weaning, and euthanasia are some of the most stressful practices performed on cow-calf operations. Although strategies to minimize stress exist, their use on western Canadian cow-calf operations is unknown. The objectives were to describe current stress-associated practices on western Canadian cow-calf operations, describe producer and operation demographics associated with the use of nonabrupt weaning methods, and explore producer perceptions toward these practices. A questionnaire focusing on stressful management practices was delivered to 109 cow-calf producers in western Canada. Fifteen respondents were purposively selected for individual interviews. The majority of producers reported calves less than 1 wk of age were handled by manual restraint (87%) and those older than 1 wk of age were handled using a cattle squeeze or table. Most producers performed abrupt weaning (70%). Interviewees often mentioned that cost and logistics were major factors in deciding on a weaning strategy. Pasture availability and facilities were viewed as constraints toward the adoption of a nonabrupt weaning method. Animal stress was considered, as producers expressed concern that nonabrupt weaning methods may cause increased stress because of the additional handling required. Producers conveyed that animal age was a major factor that impacted weaning stress and that improved animal performance might motivate them to adopt a nonabrupt weaning strategy. Producers also expressed reluctance to change previously successful traditional approaches. Of respondents, 13% did not euthanize cattle on farm and 8% did not confirm death. Producers interviewed reported that the decision to euthanize cattle on farm was difficult and that veterinary advice was often considered. Factors that influenced their decision to euthanize included the animal's likelihood of recovery and degree of pain and distress. Finally, producers explained that they considered whether the animal was salvageable and able to be transported. Identification of common methods of handling provides focus for future research to determine optimal handling strategies. Identified barriers to nonabrupt weaning may be addressed through research, extension, or policy to encourage the adoption of weaning methods that could improve animal welfare. Confirmation of death after euthanasia was identified as an area that needs to be addressed by producer education to minimize animal stress during on-farm euthanasia.

Application of direct polymerase chain reaction assays for Campylobacter fetus subsp. venerealis and Tritrichomonas foetus to screen preputial samples from breeding bulls in cow-calf herds in western Canada

The primary objectives of this study were to estimate the prevalence of Campylobacter fetus subsp. venerealis (Cfv) and Tritrichomonas foetus in breeding bulls from a sentinel cohort of cow-calf herds in western Canada and to estimate the association between positive test status and non-pregnancy. The final objective was to evaluate the application of these tests when: i) screening bulls in the absence of a recognized problem with reproductive performance, and ii) testing for diagnosis of poor pregnancy rates. The crude apparent bull prevalence for Cfv was 1.1% [95% confidence interval (CI): 0.5% to 2.1%; 8/735] and herd prevalence was 2.6% (95% CI: 0.3% to 9.0%; 2/78). The crude apparent bull prevalence for T. foetus was < 0.001% (95% CI: 0.0% to 0.5%; 0/735) and herd prevalence was < 0.001% (95% CI: 0.0% to 4.6%; 0/78). Cows from herds where at least 1 bull was test positive for Cfv were 2.35 times more likely (95% CI: 1.01% to 5.48%; P = 0.047) to not be pregnant than those with no positive bulls. Polymerase chain reaction (PCR) testing of preputial material collected into phosphate-buffered saline (PBS) was recommended for screening for T. foetus when the pre-test probability of infection was > 1%. The same test for Cfv was not recommended for screening moderate- and low-risk herds due to the high risk of false positives. Tests for both T. foetus and Cfv can be used to investigate herds with reproductive problems when also ruling out other risk factors. Regardless of the type of test used, however, 3 negative tests are required to rule out infection in high-risk situations.

Agreement between Three Serological Tests for Neospora Caninum in Beef Cattle

During 1999, serum samples were collected from beef cows on pastures in western Canada. Some of the herds had a history of confirmed abortions associated with Neospora caninum infection. All these samples were initially analyzed using a single application of 1 common commercial enzyme-linked immunosorbent assay (ELISA) for antibodies to N. caninum. From these initial results, 239 positive and 250 negative samples were randomly selected for further testing. This group of samples was retested using the 3 commercially available ELISA tests for N. caninum as per the manufacturer's recommendations. The agreement between 2 of the ELISAs was good (k = 0.76); agreement of these 2 tests with the third test was much lower (k = 0.46 and 0.60). Quantitative agreement between tests measured by intraclass correlation coefficients was also acceptable between the first 2 tests but was almost zero when the first 2 tests were compared with the third. This information is necessary to understand the differences in seroprevalence reported in different regions from laboratories using different methods.

Optic neuropathy in a herd of beef cattle in Alberta associated with consumption of moldy corn

A group of beef cattle in eastern Alberta was investigated due to sudden onset of blindness after grazing on standing corn in mid-winter. Fumonisin-producing Fusarium spp. were isolated from the corn. Blindness was due to an optic nerve degeneration suspected to be secondary to fumonisin mycotoxin.

Demographics of the Canadian cow-calf industry for the period 1991 to 2011

The Canadian cow-calf sector is about to undergo major transformative change because of shifts in Canada's population demographics. To understand the impact of this change on the Canadian beef cow-calf sector, Statistics Canada census data from 1991 to 2011 were analyzed for trends. From 2006 to 2011, the number of Canadian cow-calf producers and operations decreased by 24.6% and 26.0%, respectively. Furthermore, as of 2011, 61.9% of producers were > 50 y of age. The number of cow-calf producers is positioned to decrease by another 40% by 2021. If Canada's cow-calf industry is to maintain its current levels of production then the average herd size will need to increase markedly. The shift towards fewer but larger operations will impact the type of veterinary services demanded by cow-calf producers, and the number of veterinarians required to service this industry. Veterinary colleges will need to examine whether they are producing graduates who will meet the changing demands of livestock producers.

A 3 T sodium and proton composite array breast coil

PURPOSE

The objective of this study was to determine whether a sodium phased array would improve sodium breast MRI at 3 T. The secondary objective was to create acceptable proton images with the sodium phased array in place.

METHODS

A novel composite array for combined proton/sodium 3 T breast MRI is compared with a coil with a single proton and sodium channel. The composite array consists of a 7-channel sodium receive array, a larger sodium transmit coil, and a 4-channel proton transceive array. The new composite array design utilizes smaller sodium receive loops than typically used in sodium imaging, uses novel decoupling methods between the receive loops and transmit loops, and uses a novel multichannel proton transceive coil. The proton transceive coil reduces coupling between proton and sodium elements by intersecting the constituent loops to reduce their mutual inductance. The coil used for comparison consists of a concentric sodium and proton loop with passive decoupling traps.

RESULTS

The composite array coil demonstrates a 2-5× improvement in signal-to-noise ratio for sodium imaging and similar signal-to-noise ratio for proton imaging when compared with a simple single-loop dual resonant design.

CONCLUSION

The improved signal-to-noise ratio of the composite array gives breast sodium images of unprecedented quality in reasonable scan times.

Retrospective analysis of western Canada's veterinary profession for the period 1991 to 2007

Veterinary directories from Canada's 4 western provincial veterinary associations provided source data for compiling demographic profiles of the veterinary profession for the years 1991, 1996, 2001, and 2007. From 1991 to 2007 the number of veterinary practitioners in western Canada increased by 1197 (79%), for a net gain of 75 veterinarians/y. Of these, 786 (66%) were companion animal (CA) practitioners, 184 (15%) mixed animal (MA) practitioners, 96 (8%) food animal (FA) practitioners, and 131 (11%) were classified as "Other." The number of veterinary clinics also increased over this same period by 301 (38%), of which 266 (88%) were CA practices, 5 (2%) MA practices, and 31 (10%) FA practices. The majority of CA (75%), MA (68%), and FA (86%) practices had ≤ 2 veterinarians.

A retrospective diagnostic laboratory survey of antimicrobial resistance in fecal Escherichia coli isolated from spring calves in western Canada

Diagnostic laboratory data on antimicrobial susceptibility of Escherichia coli isolated from feces of spring calves were evaluated retrospectively for the 5-year period from 1999 to 2003. The antimicrobials to which resistance was most prevalent were tetracycline, ampicillin, and trimethoprim/sulphamethoxazole. Resistance to 3 or more antimicrobials was found in 52.5% [95% confidence interval (CI): 47.9 to 56.6] of the E. coli isolates. Incomplete records reduced the usefulness of the diagnostic laboratory data for surveillance. Standardized patient information submitted by veterinary clinics would increase the value of this data for surveillance.

Associations between antimicrobial use and the prevalence of antimicrobial resistance in fecal Escherichia coli from feedlot cattle in western Canada

A randomized, controlled, blinded clinical trial was performed at a research feedlot in western Canada. Auction-market-derived steers (n = 288) were randomly assigned to 1 of 3 treatments: 1) no antimicrobials on arrival; 2) oxytetracycline in the starter ration for 14 d; and 3) long-acting oxytetracycline subcutaneously on day 0. Minimal inhibitory concentrations of 7 antimicrobials were determined for 3 generic fecal E. coli isolates per animal on arrival and throughout the feeding period. There was a low prevalence of antimicrobial resistance in generic E. coli isolates from calves on arrival. There were increased proportions of cattle with resistant E. coli isolates early in the feeding period among calves in groups 2 and 3. Individual animal treatments were not associated with increased proportions of cattle with resistant E. coli isolates preslaughter. There was no difference in the proportion of animals with E. coli isolates resistant to tetracycline between the treatment groups preslaughter. However, there were significantly more animals with tetracycline resistant isolates of E. coli preslaughter than at arrival.

Factors associated with veterinarians' career path choices in the early postgraduate period

Veterinarians who graduated between 2000 and 2004, inclusive, were surveyed to determine the factors associated with career path (job) switching in the early postgraduate period. The sampling frame consisted of 348 veterinarians, 285 of whom were contacted and of these, 192 (67.4%) responded to the survey. Only 28.4% of respondents had remained with their initial employer. Three main factors were associated with employee retention: the type of practice/caseload, the workload (hours worked and number of nights on-call), and the level of mentorship and support provided by the practice. Workload and mentorship were also cited as the main reasons for leaving a place of employment. More than a third (38.0%) of respondents reported leaving a position solely because of inadequate mentorship and support. A third (33.7%) of respondents who began their careers in mixed or food animal practice were no longer in these types of practice; the main reasons for leaving were related to workload and mentorship.

The demand for veterinary services in western Canada

The objective of this study was to determine the number of hours veterinarians in western Canada work per week, how they apportion their time by species, and clinics' hiring intentions for new veterinary associates. Of 1099 clinics contacted, 706 (64%) responded to the survey, representing 80% (1774/2227) of private practitioners in western Canada. Practitioners devoted 73% of their time to small animals (SA), 11% to beef practice, and 9% to horses. Sixty-four percent of clinics and 66% of practitioners were devoted exclusively to companion animal (SA and horses) practice; only 4% of clinics and 4% of practitioners were devoted exclusively to food animal practice. A total of 230 clinics were seeking to hire another veterinarian, representing 223 full-time equivalents (FTEs). When adjusted for clinics that did not respond, the total number of vacancies in western Canada could be as high as 347 FTEs with 57% of vacancies in companion animal practice. The survey, however, did not assess how determined the clinics were in their attempts to hire another associate.

Factors associated with the career path choices of veterinarians in western Canada

This second of 2 articles, relating to the veterinary profession in western Canada, explores the factors associated with veterinarians' career path choices. Among other factors, companion animal (small animal and equine) (CA) practitioners were less likely to have been raised in, or near to, a small center (< or = 10 000), were more concerned with their workload (hours of work and number of nights on-call), and preferred to work in progressive practices. Food animal (FA) practitioners were more likely to be male, have been raised in a small center, have been raised in the Province of Saskatchewan, and to have self-assessed themselves as having an above average knowledge of agriculture at the time they applied for admission to veterinary college. Mixed animal (MA) practitioners had more factors in common with FA than with CA practitioners. Three main factors were associated with leaving mixed or food animal practice: hours of work and too many nights on-call, the level of remuneration, and lack of support and mentorship.

Demographic survey of veterinarians employed in western Canada

The objective of this study was to generate demographic data on veterinarians working in western Canada. A sample of 551 veterinarians was randomly selected from a population of 2474 veterinarians employed in western Canada, 425 (77.1%) of whom responded to the survey. The respondents were evenly split between males (53.1%) and females (46.9%). More than half (58.0%) of the private practitioners practised exclusively on companion animals (small animals and horses), while 2.9% devoted 100% of their time to food animals. There were 351 respondents who had had > or = 2 employers since graduation; 80% of those who had begun their careers in companion animal (CA) practice had remained in this type of practice, while 54.3% of those who had begun their careers in mixed animal practice had switched to CA practice. Analyses of wage and workload data from 85 full-time veterinary employees showed that CA practitioners worked the fewest hours/week (47.0), had the least number of evenings on-call/month (3.7), and earned the highest hourly wage (35.79 dollars) as compared with non-CA practitioners.

Demographics and career path choices of graduates from three Canadian veterinary colleges

The classes of 2007 from the Atlantic Veterinary College, Ontario Veterinary College, and Western College of Veterinary Medicine were surveyed to determine what factors influenced the respondents' career path choices. Seventy percent (166/237) of those contacted participated in the survey of which 89.1% were female, 62.7% had an urban upbringing, and 33.0% expected to be employed in a small center (population < or = 10,000). Half (52.5%) of the respondents reported that they were interested in mixed or food animal practice at the time of entry into veterinary college, but this proportion declined to 34.2% by the time of graduation. Three factors were significantly associated with choosing a career in mixed or food animal practice: having been raised in a small center, being a male, and having a good to excellent knowledge of food animal production at the time of entry into veterinary college, as determined by a self-assessment.

Factors affecting the career path choices of graduates at the Western College of Veterinary Medicine

The objective of this study was to describe the demographics of the Class of 2006, Western College of Veterinary Medicine, and to determine which factors influenced the graduates' career path choices. Data were collected via an on-line survey and the response rate was 95.7% (67/70). The majority (57%) of graduates were starting their veterinary career in a food animal-related (FAR) job. Two factors were significantly associated with this choice: 1) those raised in, or near, a small center (population < 10 000) were 3.4 times (P = 0.03) more likely to accept a FAR position than were those raised in a large center (> 10 000), and 2) graduates with a bachelor of science in agriculture (BSc Ag) were 4.5 times (P = 0.04) more likely to begin their career as a FAR practitioner than were those without such a degree. However, 9 of the 16 graduates having a BSc Ag had an urban upbringing.