Redefining On-Farm Practices: The Perceived Impact of a Responsible Antimicrobial Use Regulation on Dairy Farmers

The global food animal industry faces a growing concern regarding antimicrobial resistance (AMR), primarily driven by the use of antimicrobials (AMs) for the treatment, control, and prevention of diseases. Addressing this challenge requires promoting responsible antimicrobial use (AMU) practices. In 2019, the province of Québec, Canada, took a significant step by implementing a regulation that limits the use of AMs of very high importance for human medicine (category I AMs as defined by Health Canada) in the food animal industry. However, the implementation of such regulation can significantly influence behavioral shifts among producers, contributing to the wider effort against AMR. Therefore, the objective of this observational study was to describe the perceived changes in knowledge of dairy producers and on-farm practices following the implementation of this regulation, using a cohort design. Data collection involved administering questionnaires to 87 dairy producers from 3 regions of the province of Québec (Estrie, Montérégie, Centre-Du-Québec) before (2017-2018) and after (2020-2021) the implementation of the regulation. The questionnaires explored the descriptive characteristics of farms, the knowledge of producers about the categorization of AMs, their on-farm treatment practices, and the perceived impacts of the regulation. Statistical analysis included t-tests and McNemar tests to compare the paired data obtained using the 2 questionnaires. The results indicated an increase in the knowledge score (the number of AMs correctly categorized by the producers by their importance for human medicine) after the implementation of the regulation, suggesting an improved understanding of the categorization of AMs based on their importance for human medicine. Trends in AMU practices for treating clinical mastitis and reproductive diseases suggested that category I AMs were less likely to be reported as the primary treatment after the regulation, while category II AMs were more often reported as primary treatment. Adoption of the selective dry cow therapy method significantly increased, while the use of teat sealants remained unchanged. Moreover, producers had divergent perceptions regarding the effect of the regulation on the cure rates and disease frequencies. This disparity emphasizes the need for comprehensive data collection to discern the risks associated with such regulatory shifts. The study acknowledges several limitations, including the potential for recall bias, confirmation bias, and desirability bias. Despite these limitations, this study shows that implementing regulations to encourage responsible AMU drives positive transformations in producers' knowledge and on-farm practices. This underscores the pivotal impact of proactive interventions in combating the escalating threat of AMR within the global food animal industry.

Veal calves management in Québec, Canada: Part I. Association between passive immunity transfer at arrival and health disorders

Morbidity and mortality remain important concerns for veal production which traditionally involves very young calves being transported directly from dairy farms to calf-raising facilities or sold through auction markets from dairy farms. There are few studies that examine the relationship between transfer of passive immunity and health outcomes in veal production in Québec. The objective of this study was to investigate the risk factors associated with morbidity and mortality in milk and grain-fed veal facilities in Québec. Between October 2017 and December 2018, a prospective cohort study was conducted on 59 batches of milk- and grain-fed veal calves from Montérégie and Centre du Québec regions in Québec, Canada. A total of 30 calves per batch were randomly sampled for the transfer of passive immunity (TPI) status using the Brix refractometer (serum threshold ≥ 8.4%). Throughout the production cycle, arrival, treatment, mortality, and slaughter records of each batch of calves were extracted and used to quantify individual- and group-level risk factors. Morbidity and mortality were modelled through generalized linear mixed models (GLMMs) using a logit link, as function of categorical variables (individual inadequate TPI, arrival season, purchasing sites, and arrival weights) and a continuous variable (proportion of inadequate TPI in the batch). Given that the health and performance data are usually collected retrospectively under commercial settings, incomplete data was recognized as a potential issue. Thus, multiple imputation models were used. From 59 batches where 1729 calves were sampled for measuring TPI, 1084 calves had a serum Brix% < 8.4% giving a prevalence of 62.7% of inadequate TPI. The prevalence of morbidity and mortality in those 59 batches were not associated with the batch-level inadequate TPI prevalence. On the other hand, individual calves with inadequate TPI had higher odds of morbidity (OR: 1.56; 95% CI: 1.2-2.05, P = 0.001) compared to those calves with adequate TPI. Odds of mortality, on the other hand, were not significantly affected by inadequate TPI (OR:1.27; 95% CI: 0.74-2.18, P = 0.3). Calves arriving to the facility during the winter season had lower odds of mortality than those arriving in fall (OR:0.16; 95% CI: 0.03-0.78, P = 0.02). In conclusion, this study suggests that inadequate TPI, as assessed upon arrival in veal farms, remains an important concern for negative health outcomes in veal calves.

Clonal and plasmidic dissemination of critical antimicrobial resistance genes through clinically relevant ExPEC and APEC-like lineages (ST) in the dairy cattle population of Québec, Canada

Antimicrobial resistance can be effectively limited by improving the judicious use of antimicrobials in food production. However, its effect on the spread of AMR genes in animal populations is not well described. In the province of Québec, Canada, a new legislation implemented in 2019 has led to an unprecedented reduction in the use of critical antimicrobials in dairy production. We aimed to investigate the potential link between ESBL/AmpC E. coli isolated before and after legislation and to determine the presence of plasmids carrying genes responsible for critical AMR. We collected fecal samples from calves, cows, and manure pit from 87 Québec dairy farms approximately 2 years before and 2 years after the legislation came into effect. The whole genomes of 183 presumptive ESBL/AmpC E. coli isolated after cefotaxime enrichment were sequenced. Their phylogenetic characteristics (MLST, serogroup, cgMLST) and the presence of virulence and resistance genes and replicons were examined. A maximum likelihood phylogenetic tree was constructed based on single nucleotide polymorphism (SNPs). We identified 10 clonal lineages (same cgMLST) and 7 clones (SNPs ≤ 52). Isolates belonging to these clones could be found on different farms before and after the legislation, strongly suggesting a clonal spread of AMR genes in the population during this 4-year period. All isolates were multidrug resistant (MDR), with clone 2 being notable for the presence of macrolide, fluoroquinolone, and third-generation cephalosporin resistance genes. We also identified clinically relevant ExPEC (ST10) and APEC-like lineages (ST117, ST58, ST88) associated with the presence of ExPEC and APEC virulence genes, respectively. Our data also suggests the presence of one epidemic plasmid belonging to the IncY incompatibility group and carrying qnrs1 and blaCTX-M-15. We demonstrated that AMR genes spread through farms and can persist over a 4-year period in the dairy cattle population through both plasmids and E. coli clones, despite the restriction of critical antimicrobial use. MDR ExPEC and APEC-like STs are present in the normal microbiota of cattle (more frequently in calves). These data increase our knowledge on gene dissemination dynamics and highlight the fact that biosecurity measures should be enhanced in this industry to limit such dissemination.

Prevalence of cutaneous and mucosal lesions in dairy cattle admitted to a Canadian Veterinary Teaching Hospital from 2018 to 2019

BACKGROUND

The prevalence, anatomical distribution, or nature of cutaneous, hair and oral mucosal abnormalities (CHMAs) in cattle is uncertain.

OBJECTIVES

To determine how often dairy cattle admitted to a veterinary teaching hospital (VTH) had CHMAs (except for foot and ear canal) on physical examination and if there was an age-related difference.

ANIMALS

Four hundred and thirty-three cattle: cattle <3 months (n = 85), cattle 3 to 24 months (n = 73), and cattle >24 months (n = 275).

METHODS

In this descriptive, observational, prospective study, CHMAs of dairy cattle admitted to the VTH of the Université de Montréal were recorded over 1 year. Prevalences were calculated. Dermatological examinations were performed within 48 hours of admission, according to a glossary. Chi-square tests were used to compare prevalence between age groups.

RESULTS

The 433 cattle were mostly females (97.5%) and of the Holstein breed (89.8%). The prevalence of cattle <3 months presenting with at least 1 identifiable CHMA was 65% (55/85). In cattle 3 to 24 months old, it was 90% (66/73), and in cattle >24 months, it was 99.3% (273/275). There were significant differences (P < .001) between the prevalence of CHMAs localized on the ischia, ilia, stifles, hocks, carpi, flank, lateral neck, dorsal cervical, and cornual regions in cattle >24 months vs <3 months.

CONCLUSIONS AND CLINICAL IMPORTANCE

CHMAs were highly prevalent and age-specific. Calluses on the carpi and hocks of cattle >24 months were the most common CHMAs.

Accuracy of testing strategies using antibody-ELISA tests on repeated bulk tank milk samples and/or sera of individual animals for predicting herd status for Salmonella dublin in dairy cattle

There is currently no perfect test for determining herd-level status for Salmonella Dublin in dairy cattle herds. Our objectives were to evaluate the accuracy, predictive ability, and misclassification cost term of different testing scenarios using repeated measurements for establishing the S. Dublin herd status. Diagnostic strategies investigated used repeated bulk tank milk antibody-ELISA tests, repeated rounds of blood antibody-ELISA tests on non-lactating animals or a combination of both approaches. Two populations hypothesized to have different S. Dublin prevalences were included: (i) a convenience sample of 302 herds with unknown history of infection; and (ii) a cohort of 58 herds that previously tested positive to S. Dublin. Bulk milk samples were collected monthly for 6-7 months and serum were obtained from 10 young animals on two occasions, at the beginning and end of bulk milk sampling period. A series of Bayesian latent class models for two populations and comparing two tests were used to compare bulk milk-based to serum-based strategies. Moreover, Monte Carlo simulations were used to compared diagnostic strategies combining both types of samples. For each diagnostic strategy, we estimated the predictive values using two theoretical prevalences (0.05 and 0.25). Misclassification cost term was also estimated for each strategy using these two prevalences and a few relevant false-negative to false-positive cost ratios. When used for screening a population with an expected low prevalence of disease, for instance for screening herds with no clinical signs and no previous S. Dublin history, a diagnostic strategy consisting of two visits at 6 months interval, and with herd considered positive if bulk milk PP% ≥ 35 and/or ≥ 1/10 animals are positive on one or both visits could be used to confidently rule-out S. Dublin infection (median negative predictive value of 0.99; 95% Bayesian credible intervals, 95BCI: 0.98, 1.0). With this approach, however, positive results should later be confirmed with more specific tests to confirm whether S. Dublin is truly present (median positive predictive value of 0.36; 95BCI: 0.22, 0.57). The same diagnostic strategy could also be used confidently to reassess the S. Dublin status in herds with a previous S. Dublin history. When use for such a purpose, the predictive value of a positive result could be greatly improved, from 0.78 (95BCI: 0.65, 0.90) to 0.99 (95BCI: 0.94, 1.0) by requiring ≥ 1 positive result on both visits, rather than at any of the two visits.

Health indicators in surplus calves at the time of arrival at auction markets: Associations with distance from farms of origin in Québec, Canada

This study evaluated the associations between estimated distance from farms' locations to auction markets, and health indicators of surplus dairy calves sold during summer 2019 and winter 2020 in Québec, Canada. A total of 3,610 animals from 1,331 different farms were used in this cross-sectional cohort study. Geographic coordinates (latitude and longitude) were obtained for each farm and the 2 participating livestock auction markets. Calves' abnormal physical signs (APS) were noted upon arrival at the auction market as they were examined by trained research staff. The haversine distance between the farm and the auction market was evaluated using geographic coordinates and categorized. Generalized linear mixed models were used for statistical analyses. The main APS observed were ocular discharge (34.9%), abnormal hide cleanliness (21.2%), swollen navel (17.2%), dehydration score 1 (at least one of the 2 following clinical signs: persistent skin tent or sunken eye, 12.9%), and dehydration score 2 (both clinical signs mentioned above, 6.5%). Calves from farms located at greater distances from the auction markets (≥110 km) had a higher risk ratio [RR = 1.08; 95% confidence internal (CI) = 1.03, 1.13] for dehydration than those from lesser distances (0-25 km). During the summertime, a RR of 1.18 (95% CI = 1.15, 1.22) was observed for dehydration compared with wintertime. A 2-way interaction between estimated distance and season showed a higher prevalence of ocular discharge for calves from farms at distances greater than or equal to 110 km during the summer (RR = 1.11; 95% CI: 1.04, 1.20) than for calves from farms located at lesser distances (0-25 km). These results demonstrate that calves from farms located at greater distances from the auction markets had more APS, mainly during the summer. A better understanding of the transport conditions and interaction with management at the farm of origin is determinant to mitigate the impact of the journey on surplus calf health.

Description of Antimicrobial-Resistant Escherichia coli and Their Dissemination Mechanisms on Dairy Farms

Despite its importance in veterinary medicine, there is little information about antimicrobial resistance (AMR) and its transmission in dairy cattle. The aim of this work is to compare AMR phenotypes and genotypes in resistant Escherichia coli and to determine how the resistance genes spread among the E. coli population on dairy farms in Québec, Canada. From an existing culture collection of E. coli isolated from dairy manure, a convenient selection of the most resistant isolates (a high level of multidrug resistance or resistance to broad-spectrum β-lactams or fluoroquinolones) was analyzed (n = 118). An AMR phenotype profile was obtained for each isolate. Whole genome sequencing was used to determine the presence of resistance genes, point mutations, and mobile genetic elements. In addition, a subset of isolates from 86 farms was taken to investigate the phylogenetic relationship and geographic distribution of the isolates. The average agreement between AMR phenotypes and genotypes was 95%. A third-generation cephalosporin resistance gene (bla_CTX-M-15), a resistance gene conferring reduced susceptibility to fluoroquinolones (qnrS1), and an insertion sequence (ISKpn19) were detected in the vicinity of each other on the genome. These genes were harbored in one triplet of clonal isolates from three farms located >100 km apart. Our study reveals the dissemination of resistant E. coli clones between dairy farms. Furthermore, these clones are resistant to broad-spectrum β-lactam and fluoroquinolone antimicrobials.

Barriers and facilitators to implementing a new regulation restricting antimicrobial use in dairy production in Québec, Canada: A qualitative study

With the emergence of antimicrobial resistance (AMR), many countries are implementing restrictive regulations to reduce antimicrobial use (AMU) in animal production. Although these measures are effective at the national level, their implementation may generate challenges for producers and veterinarians. The objective of this study was to explore the barriers and facilitators of implementing a new regulation restricting the use of antimicrobials of very high importance for human health in the dairy production sector in the province of Québec, Canada. Individual interviews were conducted with fifteen veterinarians and twenty-seven dairy producers. Thematic analysis was performed based on the COM-B model of behavior change (capability-opportunity-motivation-behavior). Our results indicated that the lack of availability of alternative treatments, the long delays related to diagnostic tests and the fear of economic consequences were major barriers to the implementation of the regulation. A small number of producers also perceived that the regulation negatively impacted the health and wellbeing of their animals. Additionally, participants acknowledged the importance of early education and training to better understand the purpose of the regulation and increase its acceptability. Lastly, most participants reported that they had not only reduced their use of antimicrobials of very high importance for human health following the regulation, but they had also increased preventive practices on their farm. This study reveals that the implementation of restrictive regulations to reduce AMU in animal production can lead to multiple challenges in practice. Our results highlight the need for better communication and training of producers and veterinarians before and during the implementation of similar regulations in the future and underline the importance of measuring the direct and indirect impacts of those regulations on productivity and on animal health and wellbeing.

Presence or severity of hypophosphatemia is not associated with survival outcome in postpartum downer dairy cows

OBJECTIVE

To evaluate the association between serum phosphorus concentration and the outcome of postpartum downer cows.

ANIMALS

Postpartum downer dairy cows presented over a 22-year period.

PROCEDURES

In this cross-sectional study (1994 to 2016), medical records of all postpartum downer cows presented to a referral large animal hospital were reviewed. The association between serum inorganic phosphorus concentration and survival was assessed using a multivariable logistic regression.

RESULTS

907 postpartum downer dairy cows were included and classified as hypophosphatemic (mild: > 2.25 to < 3.25 mg/dL, moderate: > 1.50 to ≤ 2.25 mg/dL, and severe: ≤ 1.50 mg/dL), normophosphatemic (≥ 3.25 and ≤ 8.76 mg/dL) or hyperphosphatemic (> 8.76 mg/dL). Hypophosphatemia was observed in 19.4% of the cows (n = 176). Of those, 54.5% (n = 96) were also hypocalcemic. Overall, 58.4% cows (n = 530) survived after hospitalization. Hypophosphatemia was not significantly associated with the outcome of postpartum downer cows (mild: OR = 1.0, 95% CI: 0.6 to 1.8; moderate: OR = 0.5, 95% CI: 0.2 to 1.1; severe: OR = 1.0, 95% CI: 0.4 to 2.4).

CLINICAL RELEVANCE

Low serum phosphorus concentration was frequently observed with hypocalcemia and was not associated with the outcome of postpartum downer cows.

Surgical treatment of a paraphimosis in a castrated alpaca secondary to a preputial avulsion

A 4-year-old recently castrated male alpaca was referred for preputial prolapse of 4 d duration. Clinical findings upon admission were a 5 cm edematous preputial prolapse with the exposed preputial epithelium ulcerated and slightly necrotic. Initial therapy included NSAIDs and local treatment. A severe local inflammatory reaction with a consequent paraphimosis occurred on the penis and prepuce presumptively secondary to the use of a common compound ointment (i.e., tetracycline, scarlet oil, and lanolin) 24 h after its application. Medical treatment and local debridement were unsuccessful in reducing the paraphimosis. The prolapse was successfully reduced by traction of the penis through a para-preputial incision under general anesthesia. The alpaca was discharged after 22 d in hospital. The alpaca is still in the herd 24 mo after discharge with no prolapse recurrence.

Interpretation of cerebrospinal fluid analysis from recumbent cows using different thresholds of red blood cell count

BACKGROUND

Hemodilution of the cerebrospinal fluid (CSF) could confound interpretation of results. Accurately predicting total nucleated cells count (TNCC) and total protein concentration (TPC) attributable to hemodilution is difficult.

OBJECTIVE

To determine the effects of hemodilution on TPC and TNCC in bovine CSF.

METHODS

Retrospective review of CSF analysis results of downer dairy cows treated at Centre hospitalier universitaire vétérinaire between January 2006 and December 2014. Descriptive statistics were performed using 3 scenarios.

RESULTS

Among the 235 samples included, red blood cell (RBC) count (RBCC) ranged from 0 to 869 220 RBC/μL (median = 6.6), TPC ranged from 0.04 to 6.51 g/L (median = 0.27), and TNCC ranged from 0 to 7500 cell/μL (median = 1.1). Among the 157 samples that had <30 RBC/μL (a threshold used in other species), TPC and TNCC varied between 0.13 and 1.06 g/L (median = 0.27) and between 0 and 31.4 cell/μL (median = 0.6), respectively. Eighty-four samples had TPC <0.25 g/L and TNCC ≤4.5 cell/μL. Among those 84 samples, RBCC varied between 0 and 1290 RBC/μL (median = 4.7). In 20 samples, TNCC was 0 with a variation in RBCC between 0 and 840 RBC/μL (median = 3.9). No strong correlations between RBCC and TNCC and TPC were found.

CONCLUSIONS

A cutoff around 200 RBC/μL is proposed as clinically meaninful in bovine CSF. Results between 200 and 1290 RBC/μL are equivocal.

Development of a multivariable prediction model to identify dairy calves too young to be transported to auction markets in Canada using simple physical examination and body weight

Calves born on Eastern Canadian dairy farms that are not kept in the herds are traditionally sold through auction markets and are raised for meat purposes such as veal calves. Since February 2020, a new Canadian federal regulation has forbidden calves <9 d old to be sold through auction markets. However, in the absence of a real-time birth registry consultation system, it would be of interest to look for predictors that could be associated with age to allow identification of calves too young to be transported. In the current retrospective cross-sectional study, 1,178 calves with a declared birth date (411 calves aged <9 d old; 34.9%) were assessed in 2 large Québec auction sites. Easy-to-record covariates [body weight (BW), breed phenotype, and presence of an umbilical cord remnant] as well as other clinical signs (umbilical swelling, enlargement, umbilical pain, wet umbilicus, skin tent, sunken eyes, ocular and nasal secretion, and hide cleanliness) were assessed. Two logistic regression models using age as a dichotomous dependent variable (<9 d old vs ≥9 d old) were built. The first model (model 1) considered all covariates, which were selected after univariable analyses and a backward stepwise selection process, whereas a more pragmatic model (model 2) only included the 3 easy-to-record variables (i.e., BW, breed, umbilical cord). Both models had similar accuracy to detect calves <9 d old (sensitivity of 38.4 and 37.5%, and specificity of 85.7 and 84.6% for model 1 and 2, respectively). Model 2 was subsequently more specifically studied as it employs a faster and easier assessment. Decision thresholds were tested for their robustness based on misclassification cost term (MCT) analysis with various prevalence of calves <9 d old and various costs of false-negative:false-positive ratio. Despite statistical significance, model accuracy, even if refined with MCT analysis, was limited at the individual level, showing the limits of using physical signs and BW or their combination as a reliable proxy of age. The sensitivity of these models to find calves <9 d old was not to be used for monitoring compliance with the Canadian federal regulation. The relatively high model specificity may help to use this model as a rule-in test (i.e., targeting positive calves for further investigation) rather than a rule-out test (due to its low sensitivity).

Impact of a Regulation Restricting Critical Antimicrobial Usage on Prevalence of Antimicrobial Resistance in Escherichia coli Isolates From Fecal and Manure Pit Samples on Dairy Farms in Québec, Canada

To tackle antimicrobial resistance (AMR), one of the major health threats of this century, the World Health Organization (WHO) endorsed a global action plan in 2015. This plan calls countries to develop national actions to address AMR. The province of Québec, Canada, adopted a new regulation on the 25^th of February 2019, to limit the use in food animals of antimicrobials of very high importance in human medicine. We aimed to establish the impact of this regulation by comparing the AMR situation in dairy cattle in Québec ~2 years before and 2 years after its introduction. We sampled calves, cows, and the manure pit in 87 farms. Generic and putative ESBL/AmpC E. coli were tested for susceptibility to 20 antimicrobials. Logistic regression was used to investigate whether the probability of antimicrobial resistance differed between isolates obtained from the pre and post regulation periods by sample type (calves, cows, manure pit) and in general. To identify AMR genes dissemination mechanisms, we sequenced the whole genome of 15 generic isolates. In the generic collection, at the herd level, the proportion of multidrug resistant (MDR) isolates, decreased significantly from 83 to 71% (p = 0.05). Folate inhibitor and aminoglycoside resistances demonstrated a significant decrease. However, when analyzed by sample type (calves, cows, manure pit), we did not observe a significant AMR decrease in any of these categories. In the ESBL/AmpC collection, we did not detect any significant difference between the two periods. Also, the general resistance gene profile was similar pre and post regulation. We identified both clonal and plasmidic dissemination of resistance genes. In conclusion, as early as 2 years post regulation implementation, we observed a significant decrease in MDR in the dairy industry in Quebec in the generic E. coli collection with folate inhibitor and aminoglycoside resistances showing the most significant decrease. No other significant decreases were yet observed.

Evaluation of inter-rater agreement of the clinical signs used to diagnose bovine respiratory disease in individually housed veal calves

In dairy calves raised for veal, typical clinical signs of bovine respiratory disease (BRD) are ocular discharge, nasal discharge, ear droop or head tilt, abnormal respiration, cough, and increased rectal temperature. Despite the existence of several clinical scoring systems, there are few studies on the variability of human recognition of individual BRD clinical signs. The objective of this study was therefore to assess the inter-rater agreement of BRD clinical signs in veal calves. We hypothesized that BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry and that some clinical signs have higher inter-rater agreement than others. During 2017-2018, we prospectively recorded 524 videos of physical examinations of random veal calves from 48 different batches in Québec, Canada. A researcher, not involved in the inter-rater assessment, classified each video as presence/absence of each BRD clinical sign except rectal temperature. For each of the 5 clinical signs, 15 videos with and 15 videos without the clinical signs were randomly selected to avoid kappa paradoxes. Those 30 videos were then presented in a random order to experienced raters of BRD in veal calves: 6 veterinarians, 6 technicians, and 6 producers. The raters assessed the clinical signs using scores based on the Wisconsin and California scoring system with modifications (0 = absent, 1 = mild, 2 = moderate, 3 = severe for nasal discharge, ocular discharge, and ear droop or head tilt; and 0 = absent, 1 = moderate, 2 = severe for abnormal respiration and induced cough). We used median percentage agreement (Pa), median Cohen's kappa (κ), and Gwet's agreement coefficient 1 (AC1) to assess inter-rater agreement. The effect of scale combination was also tested to determine the optimal combination (4-scale 0/1/2/3 vs. 3-scale 0/1/2 vs. 2-scale 0/1,2,3; 0,1/2,3; or 0/1,2). The differences of inter-rater agreement between veterinarians, technicians, and producers were estimated by a Wilcoxon rank-sum test. The 2-scale combination (0,1/2,3 or 0/1,2) had the highest inter-rater agreement for all clinical signs. With this combination, induced cough was the clinical sign with the highest inter-rater agreement (Pa = 0.93; κ = 0.79; AC1 = 0.87) and abnormal respiration was the sign with the lowest inter-rater agreement (Pa = 0.77; κ = 0.20; AC1 = 0.74). According to Pa and AC1 values, the 2-scale inter-rater agreement of the 5 clinical signs was good (value > 0.6). According to κ, only ear droop or head tilt and induced cough had a substantial 2-scale inter-rater agreement (κ > 0.6). In general, the 2-scale inter-rater agreement was better among veterinarians than among technicians and producers, except for the ear droop/head tilt, where agreement was better among producers. We concluded that with severity scores assessed on a scale of 2 (0,1/2,3 or 0/1,2), the inter-rater agreement of BRD clinical signs was variable according to the sign in veal calves. BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry. Future research could determine if this discrepancy could be improved by standardization training.

Survival and prognostic indicators in downer dairy cows presented to a referring hospital: A retrospective study (1318 cases)

Background

Downer cow syndrome, a common problem in dairy cattle, represents a diagnostic and therapeutic challenge for the attending veterinarian. Identifying prognostic indicators and assessing the odds of survival may improve the accuracy of the clinician's prognosis at the time of diagnosis.

Objective

To describe a population of downer dairy cows referred to a hospital and investigate predictors of outcome.

Animals

Recumbent adult dairy cows (cows unable or unwilling to stand without help) treated at a referral hospital.

Methods

Data at the time of admission were collected from medical records of downer dairy cows treated at the Centre Hospitalier Universitaire Vétérinaire between 1994 and 2016. Simple and multivariable logistic regression analyses were performed to assess the association of predictors with the outcome.

Results

Among 1318 cows included, 727 (55%) cows were discharged, and 591 (45%) cows died or were euthanized. Cows with longer time of recumbency before referral (odds ratio [OR] = 3.6), tachycardia (100‐120 beats per minute [bpm], OR = 1.93; >120 bpm, OR = 2.92), tachypnea (OR = 1.76), hypothermia (OR = 2.08), anemia (OR = 3.30), neutropenia (OR = 1.7), high aspartate aminotransferase activity (500‐1000 U/L, OR = 2.16; >1000 U/L, OR = 6.69), and increased serum creatinine concentration (OR = 1.75) had higher odds of nonsurvival.

Conclusions and Clinical Importance

These findings may help the practitioner to consider treatment options and decide if referral is likely beneficial based on the odds of success. Early recognition of low chance of survival may facilitate an early decision for euthanasia.

Prevalence of Antimicrobial Resistance and Characteristics of Escherichia coli Isolates From Fecal and Manure Pit Samples on Dairy Farms in the Province of Québec, Canada

Antimicrobial resistance (AMR) is an important burden for public health and veterinary medicine. For Québec (Canada) dairy farms, the prevalence of AMR is mostly described using passive surveillance, which may be misleading. In addition, the presence of extended spectrum β-lactamase (ESBL)/AmpC producing Escherichia coli is unknown. This observational cross-sectional study used random dairy farms (n = 101) to investigate AMR and extended spectrum β-lactamase (ESBL)/AmpC producing Escherichia coli. Twenty antimicrobials were tested on E. coli isolates (n = 593) recovered from fecal samples (n = 599) from calves, cows, and the manure pit. Isolates were mostly susceptible (3% AMR or less) to the highest priority critically important antimicrobials in humans. The highest levels of AMR were to tetracycline (26%), sulfisozaxole (23%) and streptomycin (19%). The resistance genes responsible for these resistances were, respectively: tet(A), tet(B), sul1, sul2, sul3, aph(3")-Ib (strA), aph(6)-Id (strB), aadA1, aadA2, and aadA5. ESBL analysis revealed two predominant phenotypes: AmpC (51%) and ESBL (46%) where bla _CMY-2 and bla _{CTX-M (} bla _CTX-M-1, bla _CTX-M-15, and bla _CTX-M-55) were the genes responsible for these phenotypes, respectively. During this study, 85% of farms had at least one ESBL/AmpC producing E. coli. Isolates from calves were more frequently resistant than those from cows or manure pits. Although prevalence of AMR was low for critically important antimicrobials, there was a high prevalence of ESBL/AmpC-producing E. coli on Quebec dairy farms, particularly in calves. Those data will help determine a baseline for AMR to evaluate impact of initiatives aimed at reducing AMR.

Comparison of thoracic ultrasonography and thoracic radiography to detect active infectious bronchopneumonia in hospitalized dairy calves

Background

The best test between thoracic ultrasonography (TUS) and thoracic radiography (TR) or the best combination of tests (series or parallel) to detect active infectious bronchopneumonia (BP) in hospitalized dairy calves remains unknown.

Hypothesis/Objectives

To estimate performances of TUS and TR to detect active BP in hospitalized dairy calves and to determine the best strategy for using these tests based on a panel diagnosis method (PDM). Performances of TUS and TR were hypothesized to be equivalent.

Animals

Fifty hospitalized dairy calves (≥7 days old; ≤100 kg; standing; pCO₂ ≥ 53 mm Hg; any reason of presentation).

Methods

Each calf prospectively and sequentially underwent physical examination, thoracic auscultation, blood analyses, and TUS and TR. Three blinded experts determined whether active BP was present/absent based on PDM. Krippendorff's alpha measured interexpert agreement. The sensitivities (Se) and specificities (Sp) of TUS and TR alone and in series or parallel were compared (McNemar's test; P < .05).

Results

Interexpert agreement was moderate at 0.58 (95%CI: 0.42; 0.73). The Se and Sp of TUS were 0.84 (95%CI: 0.60; 0.97) and 0.74 (95%CI: 0.57; 0.86), respectively. The Se and Sp of TR were 0.89 (95%CI: 0.67; 0.99) and 0.58 (95%CI: 0.39; 0.75), respectively. No significant difference was found in the Se and Sp of TUS and TR when analyzed alone, in series or in parallel.

Conclusion

Thoracic ultrasonography or TR alone equally detected active BP in hospitalized dairy calves. Series or parallel analysis provided no additional benefit. Its ease of use and widespread accessibility support using TUS as a first‐line test to detect active BP in hospitalized dairy calves.

Scoping review on clinical definition of bovine respiratory disease complex and related clinical signs in dairy cows

Bovine respiratory disease complex (BRD) is a worldwide multifactorial infectious disease. Antimicrobials are commonly used for treating BRD because bacteria are often involved. The clinical diagnosis of BRD is a challenge, especially in adult dairy cows, where information on this syndrome is scant. Having a definition based on consistent and reliable clinical signs would improve the accuracy of BRD diagnosis and could help to develop an optimal treatment approach by an early detection. The aim of this scoping review was to review clinical signs that could be recognized by producers in dairy cattle suffering from naturally occurring infectious respiratory disease, as reported in the literature. A review of the literature was performed for articles published between January 1, 1990 and January 1, 2020. The search of literature in English, French, and Italian languages included 2 different databases (Pubmed, https://pubmed.ncbi.nlm.nih.gov/; CAB abstract, https://www.cabi.org/publishing-products/cab-abstracts/). Clinical signs were categorized as follows: (1) "general manifestations of disease," which included behavioral changes or fever; (2) "alterations in respiratory function," which included clinical signs specifically associated with the respiratory tract examination; and (3) "clinical signs of other body systems," which included clinical signs related to other systems such as diarrhea or subcutaneous emphysema. The focus of the review was on clinical signs that could be monitored by animal handlers and producers. A total of 1,067 titles were screened, and 23 studies were finally included. The most common general clinical signs were increased body temperature (reported in 83% of studies, n = 19), change in feed intake (26%, n = 6), altered mentation (22%, n = 5), and decreased milk production (17%, n = 4). The alterations in respiratory function noted were nasal discharge (74%, n = 17), cough (65%, n = 15), altered respiratory dynamic or dyspnea (61%, n = 14), increased respiratory rate (43%, n = 10), and ocular discharge or lacrimation (30%, n = 7). The clinical signs associated with infectious respiratory disease reported in the 23 studies generally lacked a clear description of what constitutes a deviation from normality (0-50% of studies clearly reported what was considered normal versus abnormal depending on the clinical signs). This limitation prevented any comparison between studies that apparently reported the same "clinical sign," but possibly referred to a different assessment and definition of what was considered normal versus abnormal. Therefore, the definition of clinical signs in a repeatable way with validated interobserver agreement to determine the optimal combination for the diagnosis of BRD in dairy cows is needed. This could lead to a more judicious use of antimicrobials for respiratory disease in adult dairy cows.

An observational cohort study on antimicrobial usage on dairy farms in Quebec, Canada

Quantification of antimicrobial usage (AMU) is crucial to measure the effect of intervention programs, to determine associations between usage and resistance, to compare populations, and for benchmarking purposes. The primary objective of the study was to describe quantitatively the AMU on Quebec dairy farms over 1 yr: (1) the total AMU, (2) the AMU per administration route (intramammary, injectable, oral, intrauterine), and (3) the AMU per antimicrobial class and according to the categorizations of Health Canada and the World Health Organization. The secondary objective was to assess the effect of several characteristics (herd size, level of milk production, and incidence rate of common infectious diseases) on AMU rate. The AMU data were obtained for 101 dairy farms randomly selected in 3 important Quebec dairy regions by collecting and recording all empty drug packaging and invoices for medicated feed (spring 2017 to spring 2018). The AMU rate was reported in number of Canadian defined course doses for cattle per 100 cow-years. The average herd size was 67 cows per farm, and 2/101 farms were certified organic. Overall, an estimated mean of 537 Canadian defined course doses for cattle/100 cow-years was observed. The intramammary route during lactation was the most frequently observed, followed, in decreasing order of usage, by oral route in the feed, intramammary route at drying-off, and injectable route. Oral (other than in animal feed) and intrauterine formulations were infrequently collected from the garbage cans. The 5 most frequently observed antimicrobial classes were, by decreasing order of usage, ionophores, penicillins, aminocoumarins, aminoglycosides, and polymyxins. Highest priority critically important antimicrobials as defined by the World Health Organization were mainly collected from intramammary formulations during lactation followed by injectable and drying-off intramammary formulations. The herd size was positively associated with the total AMU rate but not with the usage rate of highest priority critically important antimicrobials. Incidence of diseases along with preventive use of antimicrobials (drying-off and medicated feed with antimicrobials) explained 48% of the variance in total AMU rate.

Comparison between thoracic ultrasonography and thoracic radiography for the detection of thoracic lesions in dairy calves using a two-stage Bayesian method

Infectious bronchopneumonia is a lower respiratory tract disease with major economic consequences in dairy calves. Thoracic radiography (TR) and thoracic ultrasonography (TUS) are two imaging diagnostic procedures available in bovine medicine for identifying thoracic lesions. However, no study has investigated whether one of these tests is superior to the other or if they provide comparable results for the detection of thoracic lesions in calves. The objective of this study was therefore to estimate and to compare the performances of TUS and TR for the detection of thoracic lesions in dairy calves. A prospective cross-sectional study was performed in a hospital setting. A total of 50 calves (≥7 days old; ≤100 kg; standing; pCO2 ≥ 53 mmHg; any reason of presentation) were enrolled. Every calf underwent TUS and TR. Only calves with thoracic lesions on TUS and/or TR were controlled by thoracic computed tomography (CT) (the gold standard). Calves without lesions were not controlled by CT. A two-stage Bayesian framework was used. The sensitivities (Se) and specificities (Sp) of both tests individually and used in series or parallel were estimated. The Se and Sp of TUS were 0.81 (95 % BCI (Bayesian Credible Interval): 0.65; 0.92) and 0.90 (95 % BCI: 0.81; 0.96), respectively. The Se and Sp of TR were 0.86 (95 % BCI: 0.62; 0.99) and 0.89 (95 % BCI: 0.67; 0.99), respectively. This study did not reveal any differences between both tests. Using TUS and TR in series was more specific than using both tests in parallel. The performances of TUS alone were not different from the performances of both tests in series or in parallel. In conclusion, TUS and TR were equivalent in detecting thoracic lesions in this study. Using TUS alone allowed an accurate detection of thoracic lesions in dairy calves. Further studies enrolling a larger sample (> 400 calves) and allowing adequate power to be achieved would be necessary to confirm these results.

Clinical characteristics, treatment, and outcome for cattle that developed retroperitoneal abscesses following paralumbar fossa laparotomy: 32 cases (1995-2017)

OBJECTIVE

To describe the clinical and clinicopathologic characteristics, treatment, and outcome for cattle that developed a retroperitoneal abscess (RA) following paralumbar fossa laparotomy (PFL).

ANIMALS

32 Holstein cows with RA.

PROCEDURES

The record database of a veterinary teaching hospital was searched to identify cattle that were treated for an RA between January 1995 and March 2017. Cattle with an RA > 30 cm in diameter located 3.5 cm subjacent to the skin that had undergone a PFL < 3 months before examination for the RA were evaluated. Information extracted from the record of each cow included signalment; physical examination, clinicopathologic, and transabdominal ultrasonographic findings; treatments administered; and outcome. Milk production data were analyzed for the lactations before, during, and after RA treatment.

RESULTS

Common physical examination findings were rumen hypomotility, anorexia, and fever, and common clinicopathologic findings were anemia and neutrophilia. Abdominal palpation per rectum and transabdominal ultrasonography facilitated RA diagnosis and identification of the optimal location for drainage. Thirty of 32 cows underwent surgical drainage of the RA and prolonged administration of systemic antimicrobials. Two cows were euthanized because of concurrent peritonitis, including 1 that underwent surgical RA drainage. Thirty cows were discharged from the hospital alive, and most returned to their previous level of milk production.

CONCLUSIONS AND CLINICAL RELEVANCE

Although uncommon, RA should be suspected in cows that develop anorexia and fever within 3 months after PFL. Cows with RA often returned to their previous level of milk production, but treatment was generally prolonged and costly.

Abomasitis in calves: A retrospective cohort study of 23 cases (2006-2016)

Background

Abomasitis is a syndrome affecting young milk‐fed calves. The current veterinary literature describes mainly its necropsy findings.

Objectives

To describe the clinical presentation, complementary tests, treatments, and case‐fatality rate of calves with a clinical diagnosis of abomasitis and to identify potential factors associated with outcome.

Methods

Observational retrospective cohort study (2006‐2016). Review of the medical records of calves <3 months of age presented with abdominal and abomasal distension for <7 days that were clinically diagnosed with abomasitis at the Faculty of Veterinary Medicine of the Université de Montréal. A follow‐up examination was conducted by telephone interview.

Animals

Twenty‐three calves clinically diagnosed with abomasitis.

Results

Median age of presentation was 3 days (range, 0‐62 days). The typical duration of the clinical course was <24 hours (15/23). On admission, the 2 most common clinical signs were anorexia (13/14) and positive succussion (13/14). Hyper‐l‐lactatemia (15/16) and increased γ‐glutamyl‐transferase activity (13/14) were the most common laboratory abnormalities. Hypoproteinemia (19/22) and a left shift (15/18) of the neutrophils also were observed. The short‐term case‐fatality rate was 52% (12/23). The clinical diagnosis was confirmed on all necropsied calves. Clostridium spp. and Escherichia coli were the most frequently isolated bacteria. Based on univariate statistical analysis, the surviving calves were significantly (P < .05) less hypothermic, less acidemic, less hyper‐l‐lactatemic, and had lower serum creatinine concentrations on admission than did the deceased calves.

Conclusions and Clinical Importance

In our study, abomasitis was associated with a guarded prognosis.

Assignment of Canadian Defined Daily Doses and Canadian Defined Course Doses for Quantification of Antimicrobial Usage in Cattle

Standardized units are essential to allow quantification and comparison of antimicrobial usage (AMU) between species and regions. In Canada, defined daily and course doses have not yet been harmonized for cattle. Our objective was to assign defined daily and course doses (named DDDbovCA and DCDbovCA, respectively) for cattle in Canada, by antimicrobial agent (AM) and by route of administration, based on the label of all products containing at least one AM, marketed and authorized in Canada for use in cattle. In April and December 2019, a systematic search was performed from the online Drug Product Database (DPD) of Health Canada to identify veterinary products containing at least one AM, marketed in Canada for use in cattle. Products were divided by route of administration (intramammary, intrauterine, injectable, oral, and topical). The monograph was retrieved for each product from the DPD, or from the Canadian Edition of the Compendium of Veterinary Products (CVP), and read completely to extract recommended dosages in cattle. Standard weights were applied to compute doses if required. DDDbovCA and DCDbovCA were assigned by calculating an average of daily and course doses, respectively, by AM and route of administration. Two products were excluded from calculations because of their claim as growth promotion or feed efficiency (no longer authorized in Canada for certain categories of AM). Overall, 39 injectable, 75 oral (including 23 medicated premixes), 8 intramammary (4 for lactating cows and 4 for dry cows), 5 intrauterine, and 4 topical products were used for calculations. DDDbovCA and DCDbovCA values were assigned successfully for each AM identified, by route of administration. These metrics will allow harmonized and transparent quantification of AMU in cattle in Canada.

Pharyngeal trauma in dairy cattle: 27 cases

BACKGROUND

Characterization of the clinical signs, response to treatment and prognosis can be useful information for decision-making when evaluating cattle with pharyngeal trauma.

OBJECTIVE

To describe the signalment, history, clinicopathologic, endoscopic, ultrasonographic, radiographic, and postmortem findings as well as treatments and outcomes of cattle diagnosed with pharyngeal perforation/trauma.

ANIMALS

Review of medical records of cattle >1 month of age admitted to a Veterinary Teaching Hospital from 1995 to 2017.

METHODS

Retrospective study. Review of medical records of cattle with pharyngeal perforation/trauma identified by oral or endoscopic examination in hospital setting.

RESULTS

Twenty-seven out of 7550 (0.36%) cases met the inclusion criteria. Pharyngeal perforation/trauma was associated with the administration of a bolus in 24 (89%) cows and a magnet in 3 (11%) cases. The boluses contained monensin (n = 12), calcium salts (n = 5), iodine (n = 1), aspirin (n = 1), vitamins (n = 1), and an unknown product (n = 4). The primary clinical signs were dysphagia, swelling of the throatlatch, subcutaneous emphysema, swelling, and pain on palpation of the throatlatch. Seventeen (63%) cows were discharged whereas 10 (37%) were euthanized. Median time between the suspected traumatic event and hospital admission was 1 day (range: 0.5-3 days) and 2 days (range: 0.5-15) for surviving and nonsurviving cattle, respectively. All 5 cows that suffered pharyngeal trauma associated with administration of calcium salt bolus were euthanized.

CONCLUSIONS AND CLINICAL IMPORTANCE

Pharyngeal trauma is a rare condition in cattle. Case fatality rate increases if not diagnosed and treated promptly. The nature of the penetrating foreign body influences the outcome.

Clinical findings and diagnostic test results for calves with septic arthritis: 64 cases (2009-2014)

OBJECTIVE To describe clinical findings and diagnostic test results and identify potential prognostic indicators for calves with septic arthritis. DESIGN Retrospective case series. ANIMALS 64 calves with septic arthritis. PROCEDURES The medical record database for a veterinary teaching hospital was searched to identify calves ≤ 6 months old that were treated for septic arthritis between 2009 and 2014. Data evaluated included signalment, history, physical examination and diagnostic test results, treatment, and outcome. Descriptive data were generated, and calves were assigned to 2 groups (neonatal [≤ 28 days old] or postneonatal [29 to 180 days old]) on the basis of age at hospital admission for comparison purposes. RESULTS 64 calves had 92 infected joints; 17 calves had polyarthritis. Carpal joints were most frequently affected followed by the stifle and tarsal joints. Forty-nine bacterial isolates were identified from synovial specimens for 38 calves, and the most commonly identified isolates were catalase-negative Streptococcus spp (n = 14) and Mycoplasma bovis (9). Calves in the neonatal group had a shorter interval between onset of clinical signs and hospitalization and were more likely to have an infected carpal joint than calves in the postneonatal group. Outcome was positive for 35 calves. Synovial fluid total nucleated cell count was positively associated with a positive outcome. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that empirical antimicrobial treatment for calves with septic arthritis should target gram-positive catalase-negative cocci and M bovis and that synovial fluid total nucleated cell count might be a useful prognostic indicator.

Invited review: Microbiota of the bovine udder: Contributing factors and potential implications for udder health and mastitis susceptibility

Various body sites of vertebrates provide stable and nutrient-rich ecosystems for a diverse range of commensal, opportunistic, and pathogenic microorganisms to thrive. The collective genomes of these microbial symbionts (the microbiome) provide host animals with several advantages, including metabolism of indigestible carbohydrates, biosynthesis of vitamins, and modulation of innate and adaptive immune systems. In the context of the bovine udder, however, the relationship between cow and microbes has been traditionally viewed strictly from the perspective of host-pathogen interactions, with intramammary infections by mastitis pathogens triggering inflammatory responses (i.e., mastitis) that are often detrimental to mammary tissues and cow physiology. This traditional view has been challenged by recent metagenomic studies indicating that mammary secretions of clinically healthy quarters can harbor genomic markers of diverse bacterial groups, the vast majority of which have not been associated with mastitis. These observations have given rise to the concept of "commensal mammary microbiota," the ecological properties of which can have important implications for understanding the pathogenesis of mastitis and offer opportunities for development of novel prophylactic or therapeutic products (or both) as alternatives to antimicrobials. Studies conducted to date have suggested that an optimum diversity of mammary microbiota is associated with immune homeostasis, whereas the microbiota of mastitic quarters, or those with a history of mastitis, are considerably less diverse. Whether disruption of the diversity of udder microbiota (dysbiosis) has a role in determining mastitis susceptibility remains unknown. Moreover, little is known about contributions of various biotic and abiotic factors in shaping overall diversity of udder microbiota. This review summarizes current understanding of the microbiota within various niches of the udder and highlights the need to view the microbiota of the teat apex, teat canal, and mammary secretions as interconnected niches of a highly dynamic microbial ecosystem. In addition, host-associated factors, including physiological and anatomical parameters, as well as genetic traits that may affect the udder microbiota are briefly discussed. Finally, current understanding of the effect of antimicrobials on the composition of intramammary microbiota is discussed, highlighting the resilience of udder microbiota to exogenous perturbants.

Survival associated with cerebrospinal fluid analysis in downer adult dairy cows: A retrospective study (2006-2014)

Background

Threshold values for total nucleated cell count (TNCC) and protein concentration in cerebrospinal fluid (CSF) of downer dairy cows suggestive of a spinal cord lesion were recently published.

Objectives

Determine short‐ and long‐term survival of downer cows that underwent CSF analysis using the reported threshold values. Evaluate the prognostic value of these threshold values to predict short‐ and long‐term survival.

Animals

Two hundred and fourteen downer adult dairy cows that underwent CSF analysis during hospitalization at the Centre Hospitalier Universitaire Vétérinaire (CHUV) of the Université de Montréal.

Methods

Retrospective study. Medical records of downer adult dairy cows presented to the hospital between January 2006 and October 2014 for which CSF analysis results were available were studied. Short‐term (discharge from hospital) and long‐term (completion of lactation) survival were determined and compared in accordance with CSF TNCC and protein concentration, using a Chi‐square test.

Results

Cows with CSF TNCC and/or protein concentration above the threshold values had a significantly lower short‐term survival rate (P = .02). The odds of nonsurvival of cows with one or both CSF values above the threshold values was 2.16 times higher than the odds for cows with values under the threshold values. CSF TNCC >4.5 cells/μL had sensitivity and specificity of 17.3% (95% CI: 10.7%‐25.7%) and 92.3% (95% CI: 85.4%‐96.6%), respectively, for predicting short‐term nonsurvival. CSF protein concentration >0.39 g/L had sensitivity and specificity of 20.9% (95% CI: 13.7%‐29.7%) and 91.4% (95% CI: 84.2%‐96.0%), respectively.

Conclusions

CSF analysis above threshold values used in this study is associated with increased odds of short‐term nonsurvival.

Radiographic Study of Haematogenous Septic Arthritis in Dairy Calves

OBJECTIVES

 (1) To develop an evaluation grid to provide a systematic interpretation of calves' articular radiographs, (2) to describe radiographic lesions of septic arthritis in dairy calves less than 6 months of age, (3) to investigate potential associations between demographic data or synovial bacteriological culture results and radiographic lesions (4) to determine whether an association is present between radiographic lesions, their severity and the long-term outcome.

METHODS

 Medical records of 54 calves less than 180 days old treated for septic arthritis between 2009 and 2014 with radiographic images performed in the first 2 days after admission were reviewed.

RESULTS

 Most common radiographic findings were increased articular joint space height (n = 49), irregularity of the articular surfaces (n = 24) and subchondral bone lysis (n = 24). The number of lesions observed and their severity were associated with older calves (p = 0.02), increased time between onset of clinical signs and admission (p = 0.0001) and the culture of Trueperella pyogenes within the joint (p = 0.02). The radiographic lesions associated with negative long-term prognosis were reduction in the joint space height (p = 0.01) and subchondral bone lysis on weight-bearing surfaces (p = 0.02).

CLINICAL SIGNIFICANCE

 An evaluation grid designed for veterinarians can facilitate systematic reading of articular radiographs and can be used for dairy calves with a presumptive diagnosis of septic arthritis. This diagnostic tool may aid in establishing a prognosis and decision-making process in terms of treatment.

Validation of a clinical scoring system for bovine respiratory disease complex diagnosis in preweaned dairy calves using a Bayesian framework

•

A prediction rule using thoracic ultrasound as an imperfect test for BRD diagnosis was modeled.

•

Selection of the optimal threshold for case definition was proposed accounting for misclassification cost term analysis.

•

Probability of active infection of the lower respiratory tract was determined for all 64 clinical signs combinations.

Bovine respiratory disease complex is a major cause of illness in dairy calves. The diagnosis of active infection of the lower respiratory tract is challenging on daily basis in the absence of accurate clinical signs. Clinical scoring systems such as the Californian scoring system, are appealing but were developed without considering the imperfection of reference standard tests used for case definition. This study used a Bayesian latent class model to update Californian prediction rules. The results of clinical examination and ultrasound findings of 608 preweaned dairy calves were used. A model accounting for imperfect accuracy of thoracic ultrasound examination was used to obtain updated weights for the clinical signs included in the Californian scoring system. There were 20 points (95% Bayesian credible intervals: 11–29) for abnormal breathing pattern, 16 points (95% BCI: 4–29) for ear drop/head tilt, 16 points (95% BCI: 9–25) for cough, 10 points (95% BCI: 3–18) for the presence of nasal discharge, 7 points (95% BCI: −1 to 8) for rectal temperature ≥39.2 °C, and −1 points (95% BCI: −9 to 8) for the presence of ocular discharge. The optimal cut-offs were determined using the misclassification cost-term term (MCT) approach with different possible scenarios of expected prevalence and different plausible ratio of false negative costs/false positive costs. The predicted probabilities of active infection of the lower respiratory tract were also obtained using posterior densities of the main logistic regression model. Depending on the context, cut-off varying from 9 to 16 can minimized the MCT. The optimal cut-off decreased when expected prevalence of disease and false negative/false positive ratio increased.

Invited review: A systematic review and qualitative analysis of treatments other than conventional antimicrobials for clinical mastitis in dairy cows

Clinical mastitis is an important disease in dairies. Its treatment is mainly based on the use of antimicrobial drugs. Numerous non-antimicrobial drugs and treatment strategies have already been reported for clinical mastitis treatment, but data on their efficacy have never been collated in a systematic way. The objective of this systematic review was to identify treatments other than conventional antimicrobials for the treatment of clinical mastitis in lactating dairy cows. A systematic review was performed with studies written in English or French selected from CAB Abstracts, PubMed, and Web of Science from January 1970 to June 2014. Controlled clinical trials, observational studies, and experimental challenges were retained. Lactating dairy cows with clinical mastitis were the participant of interest. All treatments other than conventional antimicrobials for clinical mastitis during lactation were retained. Only studies comparing the treatment under investigation to a negative or positive control, or both, were included. Outcomes evaluated were clinical and bacteriological cure rates and milk production. Selection of the study, data extraction, and assessment of risk of bias was performed by 3 reviewers. Assessment of risk of bias was evaluated using the Cochrane Collaboration tool for systematic review of interventions. A total of 2,451 manuscripts were first identified and 39 manuscripts corresponding to 41 studies were included. Among these, 22 were clinical trials, 18 were experimental studies, and 1 was an observational study. The treatments evaluated were conventional anti-inflammatory drugs (n = 14), oxytocin with or without frequent milk out (n = 5), biologics (n = 9), homeopathy (n = 5), botanicals (n = 4), probiotics (n = 2), and other alternative products (n = 2). All trials had at least one unclear or high risk of bias. Most trials (n = 13) did not observe significant differences in clinical or bacteriological cure rates in comparison with negative or positive controls. Few studies evaluated the effect of treatment on milk yield. In general, the power of the different studies was very low, thus precluding conclusions on noninferiority or nonsuperiority of the treatments investigated. No evidence-based recommendations could be given for the use of an alternative or non-antimicrobial conventional treatment for clinical mastitis. However, probiotics and oxytocin with or without frequent milk out should not be recommended. We concluded that homeopathic treatments are not efficient for management of clinical mastitis.

A randomised clinical trial of a metaphylactic treatment with tildipirosin for bovine respiratory disease in veal calves

BACKGROUND

Bovine respiratory disease (BRD) is a major problem in veal calf rearing units. The objective of this randomised clinical trial was to assess the effectiveness of tildipirosin as a metaphylactic treatment in veal calves on the number of BRD treatments, lung consolidation on thoracic ultrasonography (TUS) and average daily gain (ADG). A total of 209 veal calves from a pre-weaning fattening unit were randomly allocated to receive one of two treatments (tildipirosin 4 mg/kg, subcutaneously, n = 109; placebo 0.9% saline, subcutaneously, n = 100) at day 12 after entry in the pre-weaned unit. The calves were followed for a 70-day period. Occurrence of mortality and BRD treatments were recorded during the pre-weaning period. At days 1, 12 and 30, TUS and clinical scores were performed and ADG was measured during the first and second months of feeding.

RESULTS

The use of a metaphylactic treatment of tildipirosin 12 days after arrival of the veal calves was not associated with the number of BRD treatments performed by the producer, ultrasonographic lung consolidation or weight gain (P < 0,05). In this cohort of calves, the proportion of calves treated for BRD by the producer was low at 14% (29/209). However, 13% (26/209) of calves included in the study already had ultrasonographic lung consolidation lesions 12 days after their arrival, which was before treatment time, and 27% (56/209) had lung consolidation at day 30.

CONCLUSION

In this study population with a low BRD prevalence, we were not able to detect any benefit of tildipirosin as a metaphylactic treatment of BRD at day 12 after arrival based on BRD treatments, TUS, and ADG.

Use of a novel surgical approach for treatment of complete bilateral membranous choanal atresia in an alpaca cria

CASE DESCRIPTION A 4-hour-old 6.3-kg (13.9-lb) female alpaca cria was evaluated because of severe respiratory distress and difficulty nursing since birth. CLINICAL FINDINGS The cria had open-mouth breathing and cyanotic membranes, with no airflow evident from either nostril. Supplemental oxygen was delivered, and the patient was anesthetized and intubated orotracheally; a CT evaluation of the head confirmed bilateral membranous obstruction of the nasal cavities, consistent with complete bilateral choanal atresia. TREATMENT AND OUTCOME Choanal atresia was treated with an endoscopically assisted balloon-dilation technique, and temporary tracheostomy was performed. Stenosis recurred, requiring revision of the repair and intranasal stent placement 3 days after the first surgery. The tracheostomy tube was removed the next day. Complications during hospitalization included mucoid obstruction of the tracheostomy tube, granulation tissue development in the trachea near the tracheostomy site, mucoid stent obstruction, aspiration pneumonia, and presumed partial failure of passive transfer of immunity. The stents were removed 2 weeks after admission, and the cria was discharged 3 days later. The owner was advised that the animal should not be bred. At last follow-up 3 years later, the alpaca was doing well. CLINICAL RELEVANCE Surgical treatment with a balloon-dilation technique and placement of nasal stents with endoscopic guidance were curative in this neonatal alpaca with bilateral membranous choanal atresia. Computed tomography was useful to determine the nature of the atresia and aid surgical planning. Because a genetic component is likely, owners should be advised to prevent affected animals from breeding.

Cerebrospinal Fluid Analysis in Recumbent Adult Dairy Cows With or Without Spinal Cord Lesions

Background

Diagnosis of central nervous system (CNS) lesions in recumbent dairy cattle (RDC) is challenging because neurologic examination is limited and medical imaging often is challenging or unrewarding. Cerebrospinal fluid (CSF) analysis is useful in the diagnosis of CNS disorders in cattle. However, its utility in identifying spinal cord lesions in RDC remains to be evaluated.

Hypothesis/Objectives

We hypothesized that CSF analysis would discriminate between RDC with and without spinal cord lesions.

Animals

Twenty‐one RDC with spinal cord lesions (RDC+) and 19 without (RDC−) were evaluated.

Methods

Spinal cord lesions were confirmed at necropsy. Signalment, clinical findings, and CSF results were compared retrospectively. Total nucleated cell count and differential, protein concentration, and red blood cell count in RDC+ and RDC− were compared.

Results

Neoplasia, trauma, and infectious processes were the most frequent spinal cord lesions identified. Cerebrospinal fluid protein concentrations and TNCC were significantly higher in RDC+ compared to RDC− (P = .0092 and P = .0103, respectively). Additionally, CSF protein concentrations and TNCC in RDC− were lower than previously published reference ranges. Using an interpretation rule based on CSF protein concentration and TNCC, it was possible to accurately identify 13 RDC with spinal cord lesions and 6 RDC without lesions. It was not possible to determine spinal cord status in the remaining 18 RDC.

Conclusions and Clinical Importance

Cerebrospinal fluid analysis is valuable in the evaluation of spinal cord status in RDC. The prognosis associated with these findings remains to be determined.

Cholangiohepatitis in Dairy Cattle: 13 Cases

Background

The signalment, clinicopathologic, bacteriological, histopathological, ultrasonographic characteristics, and the treatment and outcomes of adult cattle with cholangiohepatitis are poorly defined.

Animals

Thirteen Holstein cows with cholangiohepatitis.

Methods

Retrospective study of medical records of cattle admitted to the CHUV and the AVC between 1992 and 2012 and 2000 and 2012, respectively, for cattle older than 3 months of age with a histopathological diagnosis of cholangiohepatitis. Cholangiohepatitis was defined as the presence of portal inflammation surrounding or infiltrating bile ducts, with or without epithelial damage, and extending into the adjacent lobules.

Results

At the time of diagnosis of cholangiohepatitis, cows had decreased appetite (n = 7) or were anorectic (n = 6), had fever (n = 5), and had tachycardia (n = 8). Icterus was detected in 5 cows. Yellow discoloration was identified on the skin of the udder (n = 3), conjunctiva (n = 2), and vulva (n = 1). There was leukocytosis (n = 6), neutrophilia (n = 9), and hyperfibrinogenemia (n = 8). Alteration in the serum biochemistry profile included hyperglobulinemia (n = 8), hypoalbuminemia (n = 10), increased activity of GGT (n = 12), AST (n = 8), and ALP (n = 10), and hyperbilirubinemia (n = 10). Histopathological diagnosis included mild, subacute, nonsuppurative cholangiohepatitis (n = 4), mild suppurative cholangiohepatitis (n = 4), mild mixed (neutrophilic and lymphocytic) cholangiohepatitis (n = 3), and moderate, chronic, nonsuppurative cholangiohepatitis (n = 1). Six cows were discharged from the hospital, and 7 were euthanized.

Conclusions and Clinical Importance

Cholangiohepatitis is a rare condition in adult cattle. Antemortem diagnosis can be challenging because clinical signs are unspecific.

Long-term mechanical milking status of lacerated teat repaired surgically in cattle: 67 cases (2003-2013)

This study evaluated the long-term prognosis of return to normal mechanical milking after reconstructive teat surgery and determined the factors that have an impact on the outcome. A retrospective study of 67 dairy cows with teat lacerations was performed. Milking status at discharge and at long-term follow-up was adequate for 83% and 75% of the cows, respectively. No statistically significant differences were detected between the long-term prognosis and the age of the cow, the stage of lactation at presentation, or the configuration of the laceration. Lacerations repaired more than 24 hours after the trauma were more frequently associated with a negative outcome (P = 0.05). Mastitis was the most frequent complication (n = 17) and had a statistically significant negative impact on long-term prognosis (P = 0.02). Reconstructive surgery of lacerated teat in dairy cows can help establish return to normal mechanical milking.

Systematic Review of the Diagnostic Accuracy of Haptoglobin, Serum Amyloid A, and Fibrinogen versus Clinical Reference Standards for the Diagnosis of Bovine Respiratory Disease

BACKGROUND

Bovine respiratory disease (BRD) is a worldwide animal health concern especially in feedlot, dairy, and veal calves. One of the greatest challenges is the absence of a gold standard for achieving an accurate antemortem diagnosis. Various blood markers, including the acute-phase proteins (AAP), have been proposed as potential valuable tools for BRD diagnosis.

OBJECTIVES

To perform a systematic review of the literature to assess the accuracy of selected APP (haptoglobin [Hp], serum amyloid A [SAA], and fibrinogen [Fb]) as diagnostic tools for cattle with naturally occurring BRD when compared with clinical reference standards of diagnosis.

METHODS

This review was performed with eligible studies selected from CAB Abstract and MEDLINE from 1946 to 2015, as well as the "gray literature." Methodological quality of included studies was assessed using the QUADAS-2 tool developed for diagnostic accuracy studies. The accuracy parameters sensitivity (Se) and specificity (Sp) were obtained from the articles or through contact with the authors when not directly reported.

RESULTS

A total of 314 studies were identified, from them, 23 met inclusion criteria as diagnostic studies for naturally occurring BRD. Quality of studies showed high risk of bias for case selection (70% of articles) and unclear risk of bias for index test (65%), reference standard (74%), and flow and timing (61%). There were high concerns regarding applicability for case selection (61% of studies) and reference standards used for defining BRD (48%). The concerns regarding index test application were low (83% of the studies). Only 4-8 studies could be included in the meta-analysis for each APP. No pooled estimates or pooled accuracy measurements were performed due to the low number of studies and multiple differences between studies, including reference standard definitions.

CONCLUSIONS AND CLINICAL IMPORTANCE

On the basis of these findings, it is not possible to make conclusions regarding the accuracy of APP for BRD diagnosis. The reporting of accuracy of APP for BRD detection is inconsistent among studies. Recommendations to improve capability for future meta-analyses in this area include reporting studies on diagnostic tests following the Standard for the Reporting of Diagnostic Accuracy Studies (STARD), as well as trying to standardize BRD definition across future studies.

IMAGING DIAGNOSIS-TRAUMATIC ABOMASITIS CAUSED BY FOREIGN BODIES IN A COW

A 2-year-old Holstein cow presented with a history of colic signs of 3 days' duration that had not responded to routine medical therapy. Physical examination findings were consistent with tachycardia and colic. Ultrasonographic examination of the abomasum revealed a thin hyperechoic line producing a cone shadow. Radiography of the cranial abdomen revealed two radiopaque objects within the abomasum. Right paracostal laparotomy and abomasotomy permitted palpation and manual removal of two metallic foreign bodies and a small quantity of gravel. The animal recovered well after surgery and no signs of colic were observed. Her appetite and rumination were also improved.

Ultrasonography of the Tympanic Bullae and Larynx in Cattle

Diseases of the middle ear or the larynx are not numerous in cattle but their diagnosis can be challenging for veterinary practitioners in the field. This article presents the ultrasonography of these 2 anatomic structures in order to provide new diagnostic tools to veterinary practitioners in the field. Brief anatomic reminders are first reported. The scanning techniques and normal images are then described. Finally, abnormal images of specific conditions are presented.

Respiratory pathogens in Québec dairy calves and their relationship with clinical status, lung consolidation, and average daily gain

Background

Bovine respiratory disease (BRD) is 1 of the 2 most important causes of morbidity and mortality in dairy calves. Surprisingly, field data are scant concerning the prevalence of respiratory pathogens involved in BRD in preweaned dairy calves, especially in small herds.

Objectives

To identify the main respiratory pathogens isolated from calves in Québec dairy herds with a high incidence of BRD, and to determine if there is an association between the presence of these pathogens and clinical signs of pneumonia, lung consolidation, or average daily gain.

Animals

Cross‐sectional study using a convenience sample of 95 preweaned dairy calves from 11 dairy herds.

Methods

At enrollment, calves were weighed, clinically examined, swabbed (nasal and nasopharyngeal), and lung ultrasonography was performed. One month later, all calves were reweighed.

Results

Twenty‐two calves had clinical BRD and 49 had ultrasonographic evidence of lung consolidation. Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni were isolated in 54, 17, and 12 calves, respectively. Mycoplasma bovis was identified by PCR testing or culture in 19 calves, and 78 calves were found to be positive for Mycoplasma spp. Bovine coronavirus was detected in 38 calves and bovine respiratory syncytial virus in 1. Only the presence of M. bovis was associated with higher odds of clinical signs, lung consolidation, and lower average daily gain.

Conclusions and Clinical Importance

Results suggested that nasopharyngeal carriage of M. bovis was detrimental to health and growth of dairy calves in small herds with a high incidence of BRD.

Description of thoracoscopy and associated short-term cardiovascular and pulmonary effects in healthy cattle

OBJECTIVE

To describe the optimal thoracoscopic approach to the bovine pleural cavity and evaluate the short-term effects of thoracoscopy on cardiovascular and pulmonary function of healthy cattle.

SAMPLE

6 healthy adult Holstein cows (12 hemithoraxes).

PROCEDURES

For each cow, thoracoscopy was performed in both the left and right hemithoraxes with a 24-hour interval between procedures. Cows were sedated and restrained in a standing position for each thoracoscopic examination. Examination of each hemithorax lasted for 30 minutes. Arterial blood gas variables, heart rate, and respiratory rate were assessed at predetermined times before, during, and after the procedures to monitor cardiovascular and pulmonary function. Thoracic ultrasonography was performed immediately and at 24 hours and 1 week after each thorascopic examination to evaluate the extent of residual pneumothorax.

RESULTS

Insertion of the laparoscope into the pleural cavity at the ninth intercostal space 15 cm ventral to the transverse processes of the thoracic vertebrae provided optimal visibility of structures in both the left and right hemithoraxes. Most structures of the pleural cavity were equally visible from both sides except the esophagus and the dorsal branch of the vagus nerve, which were best observed in the left hemithorax, and the pericardium, which was best observed in the right hemithorax. Mild increases in heart and respiratory rates and moderate decreases in arterial oxygen saturation and Pao2 were detected during the procedures.

CONCLUSIONS AND CLINICAL RELEVANCE

Standing thoracoscopy was well tolerated in healthy adult dairy cattle and needs to be evaluated in cattle with pulmonary disease.

Preoperative and postoperative L-lactatemia assessment for the prognosis of right abomasal disorders in dairy cattle

BACKGROUND

Preoperative L-lactatemia and heart rate have been suggested as prognostic indicators of outcome for cows with right dilatation of the abomasum or volvulus (RDA/AV). However, postoperative L-lactatemia has not been assessed as a potential prognostic tool.

OBJECTIVES

To determine the prognostic value of postoperative L-lactatemia (LAC2 ), duration of treatment (Dt), relative L-lactatemia difference (compared with preoperative L-lactatemia [LAC1 ]) ([LAC2 - LAC1 ]/LAC2 ) and change in L-lactate over time ([LAC2 - LAC1 ]/Dt) as compared to preoperative findings (LAC1 and heart rate [HR]) as prognostic factors in dairy cows with RDA/AV.

ANIMALS

A total of 41 dairy cows were included: 19 with AV and 22 with RDA; 11 cows had a negative outcome (NO) and 30 cows had a positive outcome (PO) based on telephone follow-up with owners 30 days after surgery.

METHODS

Prospective cohort study. Analysis was performed using logistic regression and comparison of area under the receiver operating characteristics curve (AUC) using nonparametric tests.

RESULTS

LAC1 > 1.4 mmol/L or LAC2 > 2.2 mmol/L had the same accuracy with sensitivity of 100% (95% CI, 75.1-100%) and specificity of 80% (95% CI, 61.4-92.3%) for predicting NO. The relative L-lactatemia difference ([LAC2 - LAC1 ]/LAC1 ) or lactate kinetics ([LAC2 - LAC1 ]/Dt) were not associated with prognosis. The AUC of the preoperative model (which included HR and lnLAC1 ) was 0.92 (95% CI, 0.83-1.0) and that of the postoperative model (including only lnLAC2 ) was 0.95 (95% CI, 0.88-1.0); these were not significantly different.

CONCLUSIONS AND CLINICAL IMPORTANCE

Postoperative L-lactatemia is helpful to predict outcome in cows with RDA/AV. The short-term change in blood L-lactate is not a useful prognostic indicator, at least during the period of time spent on the farm for surgery and treatment.

Validation of an ultrasound imaging technique of the tympanic bullae for the diagnosis of otitis media in calves

Background

Otitis media is a common disease in calves that can be subclinical, making antemortem on‐farm diagnosis challenging.

Objectives

To evaluate the sensitivity and specificity of ultrasonography of tympanic bullae for the diagnosis of clinical and subclinical otitis media and to evaluate the reproducibility of the technique.

Animals

Forty calves 19–50 days of age were selected from a veal calf farm.

Methods

Prospective study. Ultrasonography was first performed on the farm by ultrasonographer A (US A). Ultrasonography was repeated by ultrasonographer A (US A') and another ultrasonographer (US B) at the Centre Hospitalier Universitaire Vétérinaire. Images were later reread by both examiners and a diagnosis was recorded. The calves were euthanized and submitted for necropsy, and histopathologic diagnosis was used as the gold standard.

Results

Forty‐five bullae were affected by otitis media and 35 bullae were normal. Sensitivity and specificity of the ultrasound technique ranged from 32 to 63% and 84 to 100%, respectively, depending on the examiner and classification of suspicious ultrasonography results. Kappa analysis to evaluate interobserver agreement between A' and B yielded a к value of 0.53. Agreement within the same examiner (A versus A') yielded a к value of 0.48, and real‐time ultrasound versus rereading of recorded images for A' and B yielded к values of 0.58 and 0.75, respectively.

Conclusions

Sensitivity and specificity of the ultrasound imaging technique are, respectively, low and high for diagnosis of clinical and subclinical otitis media in calves, with moderate reproducibility.

Clinical management of septic arthritis in cattle

Synovial fluid, ultrasound, and radiographic imaging are common diagnostic tools for septic arthritis. Mycoplasma septic arthritis is suspected in calves with clinical signs of otitis and pneumonia. Commonly affected joints are carpus, stifle, and tarsus. Treatment strategy must include long-term antibiotics, anti-inflammatories, and joint lavage. Knowledge of communication and boundaries for commonly affected joints is essential to perform joint lavage and arthrotomy.

Comparison of thoracic auscultation, clinical score, and ultrasonography as indicators of bovine respiratory disease in preweaned dairy calves

Background

The diagnostic tools for bovine respiratory disease diagnosis include clinical inspection, thoracic auscultation, and ultrasonography.

Hypothesis

Thoracic auscultation and clinical examination have limitations in the detection of lung consolidation in dairy calves.

Animals

Prospective cohort of 106 preweaned calves from 13 different dairy herds (10 with a history of active bovine respiratory disease (BRD) in calves and 3 without suspected BRD problems).

Methods

Each preweaned calf was clinically inspected using the Wisconsin calf respiratory scoring chart (CRSC) and treatment history was noted. Systematic thoracic auscultation and ultrasonography then were performed, the latter focusing on lung consolidation. Mortality was recorded over a 30‐day period.

Results

A total of 56 of 106 calves had ultrasonographic evidence of lung consolidation. The sensitivity of thoracic auscultation to detect consolidation was 5.9% (range, 0–16.7%). Only 41.1% (23/33) of calves with consolidated lungs had been treated previously by the producers. When adding CRSC and previous BRD treatment by the producer, sensitivity of detection increased to 71.4% (40/56). The area under the receiver operating characteristics curve was 0.809 (95% CI, 0.721–0.879) for the number of areas within the lungs with consolidation and 0.743 (95% CI, 0.648–0.823) for the maximal depth of consolidation as predictors of death within 1 month after examination. These were not significantly different (P = .06).

Conclusions and Clinical Importance

This study shows that thoracic auscultation is of limited value in diagnosing lung consolidation in calves. Ultrasonographic assessment of the thorax could be a useful tool to assess BRD detection efficiency on dairy farms.