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

ABSTRACT: 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.

SUBMITTER: Buczinski S

PROVIDER: S-EPMC7114123 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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

Buczinski S S Fecteau G G Dubuc J J Francoz D D

Preventive veterinary medicine 20180504

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 res ...[more]

PMID: 29891139

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Project description:IntroductionBovine respiratory disease (BRD) has a significant impact on the health and welfare of dairy calves. It can result in increased antimicrobial usage, decreased growth rate and reduced future productivity. There is no gold standard antemortem diagnostic test for BRD in calves and no estimates of the prevalence of respiratory disease in seasonal calving dairy herds.MethodsTo estimate BRD prevalence in seasonal calving dairy herds in Ireland, 40 dairy farms were recruited and each farm was visited once during one of two calving seasons (spring 2020 & spring 2021). At that visit the prevalence of BRD in 20 calves between 4 and 6 weeks of age was determined using thoracic ultrasound score (≥3) and the Wisconsin respiratory scoring system (≥5). Hierarchical Bayesian latent class analysis was used to estimate the calf-level true prevalence of BRD, and the within-herd prevalence distribution, accounting for the imperfect nature of both diagnostic tests.ResultsIn total, 787 calves were examined, of which 58 (7.4%) had BRD as defined by a Wisconsin respiratory score ≥5 only, 37 (4.7%) had BRD as defined by a thoracic ultrasound score of ≥3 only and 14 (1.8%) calves had BRD based on both thoracic ultrasound and clinical scoring. The primary model assumed both tests were independent and used informed priors for test characteristics. Using this model the true prevalence of BRD was estimated as 4%, 95% Bayesian credible interval (BCI) (1%, 8%). This prevalence estimate is lower or similar to those found in other dairy production systems. Median within herd prevalence varied from 0 to 22%. The prevalence estimate was not sensitive to whether the model was constructed with the tests considered conditionally dependent or independent. When the case definition for thoracic ultrasound was changed to a score ≥2, the prevalence estimate increased to 15% (95% BCI: 6%, 27%).DiscussionThe prevalence of calf respiratory disease, however defined, was low, but highly variable, in these seasonal calving dairy herds.

Project description:BackgroundBovine Respiratory Disease (BRD) is a leading cause of morbidity and mortality in preweaned dairy calves. Early detection and therefore treatment are essential to minimize animal welfare concerns, particularly given that recent research also demonstrates that BRD is painful. Veterinarians are essential to ensuring calves with BRD receive appropriate treatment, but little to no research exists regarding veterinarians' perspectives about BRD detection and treatment in dairy calves. This is a critical step to determine education and outreach needs that can target BRD treatment to improve calf welfare. Thus, the objectives of the current study were to describe US veterinarians' current detection methods and treatment practices for BRD in preweaned dairy calves, understand veterinarians' rationale for treatment decisions, and identify gaps in knowledge regarding treatment and management of calf BRD.MethodsAn online survey was sent to two veterinarian-focused list-serves and newsletter. Final responses (n = 47) were analyzed using qualitative and quantitative analyses.ResultsOn-farm necropsy was the diagnostic tool most considered "extremely important" (26, 55.3%). All veterinarians indicated that BRD was at least mildly painful. However, only 53% of veterinarians (n = 25) assess pain in preweaned calves with BRD in order to make treatment decisions. Furthermore, of the veterinarians that assessed pain, 40% (n = 10) reported that their knowledge of pain assessment and treatment was adequate, but most (n = 24) considered a calf's pain-level at least "moderately important" to make BRD treatment decisions. The most important ancillary therapy for antimicrobials were NSAIDs (21, 44.7%). The ancillary therapy most often considered "extremely important" for treating BRD was NSAIDs. Qualitative analysis identified the following as factors that influenced veterinarians' willingness to provide analgesia: the farm's willingness to administer drugs, clinical signs, perceived severity of pain, the need for anti-inflammatories, and the presence of fever and comorbidities.DiscussionThis study included a small sample size and an extremely low response rate; results should therefore be interpreted with caution. Despite this limitation, important gaps in knowledge were identified, including pain assessment and consideration when making treatment decisions, and diagnostic tools. Addressing these needs in future research and outreach efforts could help ensure appropriate and timely treatment of calf BRD, including pain mitigation.

Project description:In the present study bacterial communities from both, the gastrointestinal and respiratory tract of pre-weaned dairy calves fed two different milk-feeding programs were characterized using 16S rRNA gene sequencing. Twenty female Holstein calves (38.8 ± 1.40 kg of BW) were fed pasteurized waste milk (pWM) containing residues of various antimicrobials. Twenty additional calves (38.1 ± 1.19 kg of BW) were fed milk replacer (MR) with similar nutrient composition (27.5% crude protein, 32.1% fat) compared to waste milk (28.6% crude protein, 30.0% fat) from day 1 to weaning at day 49 of study. Fecal samples and nasal swabs were collected on day 42 only from calves that were not treated with therapeutic antibiotics throughout the study, which were 8 MR and 10 pWM calves. To assess the impact of the two feeding regimes on the fecal and nasal microbiota, α and β-diversity measures were calculated, and the relative abundance of operational taxonomic units (OTUs) at different taxonomic levels was determined for each sample. In general, Chao1, PD Whole Tree, and Shannon diversity indices were similar for the fecal and nasal bacterial communities of calves regardless of the feeding regime. However, principal coordinate analysis based on unweighted Unifrac distances indicated differences in the structure of bacterial communities of calves fed milk replacer compared with those from calves fed pasteurized waste milk. The relative abundance of the Streptococcaceae family and the genus Histophilus was greater (P < 0.05) in the nasal microbiota of calves fed milk replacer than in those fed pasteurized waste milk. However, the genus Prevotella tended (P = 0.06) to be more relatively abundant in the respiratory tract of calves fed pasteurized waste milk than in those fed milk replacer. Differences in relative abundances of bacterial taxa in gut microbiota were only observed at the phylum level, suggesting that antimicrobial residues present in waste milk have a non-specific influence at a lower taxonomical level.

Project description:The objective of this study was to evaluate morbidity and mortality in preweaned dairy heifer calves based on different health, feeding, and management practices, as well as environmental factors. This study was conducted as part of the calf component of the National Animal Health Monitoring System's Dairy 2014 study, which included 104 dairy operations in 13 states. The calf component was an 18-mo longitudinal study focused on dairy heifer calves from birth to weaning; data were collected on 2,545 calves. The percentage morbidity for all calves enrolled in the study was 33.9%. Backward elimination model selection was used after univariate screening to determine which management practices and environmental factors significantly affected morbidity and mortality. The final morbidity model included birth weight, serum IgG concentration, ventilation type, and average temperature-humidity index (THI) during the preweaning period. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower predicted risk of morbidity than calves with a lower birth weight. An increase in serum IgG concentration was associated with decreased morbidity. Calves housed in positive- or cross-ventilated systems had a 2.2 times higher odds of developing disease compared with calves housed in natural ventilation systems. Average THI during the preweaning period was inversely correlated with morbidity; as THI increased, the predicted morbidity risk decreased. The percent mortality for all calves enrolled in the study was 5.0%. The final mortality model included birth weight, serum IgG concentration, amount of fat/day in the liquid diet, and morbidity. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower risk of mortality. An increase in serum IgG concentration decreased the risk of mortality. The odds of mortality were 3.1 times higher in calves fed ≤0.15 kg of fat/d in the liquid diet compared with calves fed ≥0.22 kg of fat/d. The odds of mortality were 4.7 times higher in calves that experienced any disease throughout the preweaning period than in calves with no disease. In summary, morbidity and mortality were both associated with birth weight and serum IgG concentration. Additionally, morbidity was associated with ventilation type and average monthly THI, and mortality was associated with amount of fat per day in the liquid diet and morbidity.

Project description:The California (CA) dairy industry was surveyed in July 2017 to evaluate producers' knowledge and perceptions and antimicrobial drug (AMD) use in preweaned dairy calves following the implementation of the nationwide veterinary feed directive final rule (VFD) in January 2017 and prior to statewide implementation of CA Senate Bill (SB) 27 in January 2018. Together, these regulations require veterinary oversight for all uses of medically important antimicrobial drugs (MIADs) administered to livestock in CA. Survey questionnaire was mailed to 1,361 CA Grade A milk producing dairies and calf ranches across CA resulting in a 12% (169) response. Most respondents (83%) were aware of the VFD and SB 27 changes. Use of antibiotics was perceived as important (77%) in raising preweaned dairy calves and judicious use of antibiotics was ranked as the most important antimicrobial stewardship practice, amongst record keeping, observing withdrawal periods, having a valid Veterinarian-Client-Patient-Relationship (VCPR), and use of alternatives to antibiotics. Treating sick calves was the major indication for AMD use (90.5%); however, few producers reported use of antibiotics to control (12.7%) or prevent disease (11%). Neomycin sulfate, chlortetracycline, oxytetracycline and sulfamethazine were the most used AMD. The respondents reported a decreased use of AMD in milk (10%) and in solid feed (5%), and discontinuation of one or more AMDs used in milk (18.6%) or in solid feed (5%) post-VFD rule implementation in 2017. Most respondents reported keeping treatment records and the information recorded included date (82%), dose (44%) and route (15%) of AMD used. A few respondents reported they had initiated use of alternatives to AMDs, such as vitamins (32.6%), minerals (25.6%), herbal remedies (11.6%) and pathogen specific antibodies (7%), post-VFD. The limited changes noted in AMD use could be attributed to the short period between the implementation of the VFD and the time of the survey. Our study outcomes identified opportunities to improve AMD use practices, including record keeping and use of AMD alternatives, and provides a baseline for future evaluation of the impact of these regulatory changes, as well as guidance for the future recommendations on best practices to promote judicious AMD use.

Project description:The objective of this cross-sectional study was to determine how management practices on California dairies may be associated with bovine respiratory disease (BRD) in preweaned calves. A convenience sample of 100 dairies throughout California, providing a study population of 4,636 calves, were visited between May 2014 and April 2016. During each farm visit, in-person interviews with the herd manager or calf caretaker were conducted to collect information about herd demographics, maternity pen, colostrum and calf management, herd vaccinations, and dust abatement. A random sample of preweaned calves was identified and evaluated for the presence of BRD using a standardized tool. A survey-adjusted generalized linear mixed model with a logit link function was fitted with calf as the unit of analysis and dairy as the random effect. Mean study herd size (±SE) was 1,718 (±189.9) cows. Survey-adjusted estimates of breed types in the sample were 81.6% (±0.6) Holstein, 13.1% (±0.4) Jersey, and 5.3% (±0.5) crossbred or other purebred breeds, and calf sex proportions were 73.8% (±1.0) female and 26.2% (±1.0) male. Overall survey-adjusted BRD prevalence in the study herds was 6.91% (±0.69). Housing factors positively associated with BRD were metal hutches compared with wood hutches [odds ratio (OR) = 11.19; 95% confidence interval (CI) = 2.80-44.78], calf-to-calf contact in calves >75 d of age (OR = 9.95, 95% CI = 1.50-65.86), feeding Holstein calves <2.84 L of milk or replacer per day (OR = 7.16, 95% CI = 1.23-41.68), and lagoon water used for flushing manure under hutches compared with no flush (OR = 12.06, 95% CI = 1.93-75.47). Providing extra shade over hutches (OR = 0.08; 95% CI = 0.02-0.37), feeding calves at least 90% saleable milk (OR = 0.27, 95% CI = 0.13-0.54) or pasteurized milk (OR = 0.10; 95% CI = 0.03-0.36), and feeding >5.68 L of milk or replacer per day to Jersey calves (OR = 0.04; 95% CI = 0.01-0.28) were negatively associated with BRD. Our study identified management practices on California dairies with variability and that may contribute to differences in BRD prevalence, which will be incorporated into a risk-assessment tool to control and prevent BRD in preweaned dairy calves.

Project description:BackgroundNursery farms that accept nursing and growing pre-weaned heifer calves from private dairy farms must work to prevent bovine respiratory disease (BRD). Knowledge of the BRD-associated risk factors related to calf management and calves' condition will help to develop appropriate neonatal management practices at original farms and to identify calves at higher risk for BRD at nursery farms. In this study, the relationship between BRD and calf management practices (colostrum feeding, dam parity, serum total protein concentration at introduction (TP), body weight at introduction, introduction season, and daily average growth) was investigated using observational data from pre-weaned dairy calves introduced into a nursery farm in Hokkaido, Japan between 2014 and 2018 (n = 3185). Using additive Bayesian network (ABN) analysis, which is a multivariate statistical modelling approach, the direct and indirect associations between these factors were assessed.ResultsColostrum feeding contributed to an increase in TP (correlation 1.02 [95 % CI, 0.94;1.10]), which was negatively associated with BRD directly (log odds ratio - 0.38 [- 0.46;-0.31]) and indirectly through increasing daily growth (correlation 0.12 [0.09;0.16]). Calves of multiparous dams had higher body weight at introduction (correlation 0.82 [0.74;0.89]), which indirectly reduced BRD risk through the increasing daily growth (correlation 0.17 [0.14;0.21]). Calves introduced during winter had the highest risk for BRD (log odds ratio 0.29 [0.15;0.44]), while those introduced in summer had the lowest risk (log odds ratio - 0.91 [- 1.06;-0.75]). The introduction season was also associated with BRD indirectly through dam parity, body weight at introduction, and daily growth.ConclusionsThe following calf management practices are recommended for preventing BRD in pre-weaned calves at nursery farms: (1) encouraging colostrum feeding to neonatal calves at their original farms; and (2) identifying calves with higher BRD risk, i.e., those without feeding colostrum, born to primiparous cattle, with low body weight at introduction, and/or introduced in winter, and paying intensive attention to the calves for rapid detection of BRD. ABN analysis applied enabled us to understand the complex inter-relationships between BRD incidence and the risk factors, which will help to reduce BRD incidence and to rear healthy calves at nursery farms.

Dataset Information

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

Publications

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

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