Differences between predicted outer membrane proteins of genotype 1 and 2 Mannheimia haemolytica.

BACKGROUND: Mannheimia haemolytica strains isolated from North American cattle have been classified into two genotypes (1 and 2). Although members of both genotypes have been isolated from the upper and lower respiratory tracts of cattle with or without bovine respiratory disease (BRD), genotype 2 strains are much more frequently isolated from diseased lungs than genotype 1 strains. The mechanisms behind the increased association of genotype 2 M. haemolytica with BRD are not fully understood. To address that, and to search for interventions against genotype 2 M. haemolytica, complete, closed chromosome assemblies for 35 genotype 1 and 34 genotype 2 strains were generated and compared. Searches were conducted for the pan genome, core genes shared between the genotypes, and for genes specific to either genotype. Additionally, genes encoding outer membrane proteins (OMPs) specific to genotype 2 M. haemolytica were identified, and the diversity of their protein isoforms was characterized with predominantly unassembled, short-read genomic sequences for up to 1075 additional strains. RESULTS: The pan genome of the 69 sequenced M. haemolytica strains consisted of 3111 genes, of which 1880 comprised a shared core between the genotypes. A core of 112 and 179 genes or gene variants were specific to genotype 1 and 2, respectively. Seven genes encoding predicted OMPs; a peptidase S6, a ligand-gated channel, an autotransporter outer membrane beta-barrel domain-containing protein (AOMB-BD-CP), a porin, and three different trimeric autotransporter adhesins were specific to genotype 2 as their genotype 1 homologs were either pseudogenes, or not detected. The AOMB-BD-CP gene, however, appeared to be truncated across all examined genotype 2 strains and to likely encode dysfunctional protein. Homologous gene sequences from additional M. haemolytica strains confirmed the specificity of the remaining six genotype 2 OMP genes and revealed they encoded low isoform diversity at the population level. CONCLUSION: Genotype 2 M. haemolytica possess genes encoding conserved OMPs not found intact in more commensally prone genotype 1 strains. Some of the genotype 2 specific genes identified in this study are likely to have important biological roles in the pathogenicity of genotype 2 M. haemolytica, which is the primary bacterial cause of BRD.

Effect of bandaging techniques on sub-bandage pressures in the equine distal limb, carpus, and tarsus.

OBJECTIVE: To determine the influence of 3 types of bandages on sub-bandage pressures over the distal limb, carpus, and tarsus. STUDY DESIGN: Observational study. ANIMALS: Eight healthy horses. METHODS: Each of the 6 following bandages was applied on each horse in randomized order: (1) distal limb compression bandage (DLC), (2) double layer bandage (DL), (3) inner sanctum bandage (IS), (4) carpal compression bandage (CC), (5) tarsal compression bandage (TC), and (6) adhesive elastic carpal bandage (C-ELA). Sub-bandage pressures were measured with the Picopress compression measuring system (Microlab Electonica, Nicolo, Italy) after bandage application. Carpal and tarsal bandage pressures were assessed before and after walking the horses approximately 50 m. TC pressures were also measured after creating a slit over the calcaneus. A generalized linear model was used to test the association of pressure with sensor location, bandage type, time, and potential interactions (P < .05). RESULTS: DLC (165 mmHg) and IS (167 mmHg) generated greater mean combined pressures compared with DL (146 mmHg; P = .0166). At application, CC (154 mmHg) created higher mean combined sub-bandage pressure compared with C-ELA (70 mmHg; P < .001). Pressures resulting from CC and TC decreased after walking (P < .001), whereas those associated with C-ELA were not affected. CONCLUSION: Variations to the standard DLC construct did not increase sub-bandage pressures. CC and TC pressures rapidly decreased with ambulation, whereas C-ELA pressures in healthy horses were not affected by walking. CLINICAL SIGNIFICANCE: Variations to the standard DLC offer no additional benefit in regards to increasing sub-bandage pressures. Carpal elastic bandages maintain sub-bandage pressures during ambulation and may be more appropriate for long term bandaging in ambulating horses. Creating a slit over the calcaneal tuber in TC bandages is discouraged due to rapid decreases in sub-bandage pressure.

Genomic signatures of Mannheimia haemolytica that associate with the lungs of cattle with respiratory disease, an integrative conjugative element, and antibiotic resistance genes.

BACKGROUND: Mannheimia haemolytica typically resides in cattle as a commensal member of the upper respiratory tract microbiome. However, some strains can invade their lungs and cause respiratory disease and death, including those with multi-drug resistance. A nucleotide polymorphism typing system was developed for M. haemolytica from the genome sequences of 1133 North American isolates, and used to identify genetic differences between isolates from the lungs and upper respiratory tract of cattle with and without clinical signs of respiratory disease. RESULTS: A total of 26,081 nucleotide polymorphisms were characterized after quality control filtering of 48,403 putative polymorphisms. Phylogenetic analyses of nucleotide polymorphism genotypes split M. haemolytica into two major genotypes (1 and 2) that each were further divided into multiple subtypes. Multiple polymorphisms were identified with alleles that tagged genotypes 1 or 2, and their respective subtypes. Only genotype 2 M. haemolytica associated with the lungs of diseased cattle and the sequence of a particular integrative and conjugative element (ICE). Additionally, isolates belonging to one subtype of genotype 2 (2b), had the majority of antibiotic resistance genes detected in this study, which were assorted into seven combinations that ranged from 1 to 12 resistance genes. CONCLUSIONS: Typing of diverse M. haemolytica by nucleotide polymorphism genotypes successfully identified associations with diseased cattle lungs, ICE sequence, and antibiotic resistance genes. Management of cattle by their carriage of M. haemolytica could be an effective intervention strategy to reduce the prevalence of respiratory disease and supplemental needs for antibiotic treatments in North American herds.

Large genomic differences between Moraxella bovoculi isolates acquired from the eyes of cattle with infectious bovine keratoconjunctivitis versus the deep nasopharynx of asymptomatic cattle.

Moraxella bovoculi is a recently described bacterium that is associated with infectious bovine keratoconjunctivitis (IBK) or "pinkeye" in cattle. In this study, closed circularized genomes were generated for seven M. bovoculi isolates: three that originated from the eyes of clinical IBK bovine cases and four from the deep nasopharynx of asymptomatic cattle. Isolates that originated from the eyes of IBK cases profoundly differed from those that originated from the nasopharynx of asymptomatic cattle in genome structure, gene content and polymorphism diversity and consequently placed into two distinct phylogenetic groups. These results suggest that there are genetically distinct strains of M. bovoculi that may not associate with IBK.

The impact of item-writing flaws and item complexity on examination item difficulty and discrimination value.

BACKGROUND: Failure to adhere to standard item-writing guidelines may render examination questions easier or more difficult than intended. Item complexity describes the cognitive skill level required to obtain a correct answer. Higher cognitive examination items promote critical thinking and are recommended to prepare students for clinical training. This study evaluated faculty-authored examinations to determine the impact of item-writing flaws and item complexity on the difficulty and discrimination value of examination items used to assess third year veterinary students. METHODS: The impact of item-writing flaws and item complexity (cognitive level I-V) on examination item difficulty and discrimination value was evaluated on 1925 examination items prepared by clinical faculty for third year veterinary students. RESULTS: The mean (± SE) percent correct (83.3 % ± 17.5) was consistent with target values in professional education, and the mean discrimination index (0.18 ± 0.17) was slightly lower than recommended (0.20). More than one item-writing flaw was identified in 37.3 % of questions. The most common item-writing flaws were awkward stem structure, implausible distractors, longest response is correct, and responses are series of true-false statements. Higher cognitive skills (complexity level III-IV) were required to correctly answer 38.4 % of examination items. As item complexity increased, item difficulty and discrimination values increased. The probability of writing discriminating, difficult examination items decreased when implausible distractors and all of the above were used, and increased if the distractors were comprised of a series of true/false statements. Items with four distractors were not more difficult or discriminating than items with three distractors. CONCLUSION: Preparation of examination questions targeting higher cognitive levels will increase the likelihood of constructing discriminating items. Use of implausible distractors to complete a five-option multiple choice question does not strengthen the discrimination value.

Comparison of Arthroscopic Lavage and Needle Lavage Techniques, and Lavage Volume on the Recovery of Colored Microspheres From the Tarsocrural Joints of Cadaver Horses.

OBJECTIVE: To quantify recovery of colored microspheres from normal cadaver tarsocrural joints using arthroscopic or needle lavage with 1-5 L of fluid. STUDY DESIGN: Ex vivo experimental study. ANIMALS: Adult Quarter Horse cadavers (n = 8). METHODS: After euthanasia, 1.5 × 10(6) colored microspheres were injected into each tarsocrural joint. Each joint was randomly assigned to receive lavage (5 L 0.9% NaCl) with an arthroscope (dorsomedial arthroscope and dorsolateral egress cannula) or three 14 g needles (dorsomedial ingress, dorsolateral, and plantarolateral egress). Egress fluid from each liter was collected separately over time and the number of microspheres present in each recovered liter determined by spectrophotometry. RESULTS: A significant interaction was present between treatment group and liter of fluid (P < .01). The number of microspheres recovered in the first liter of lavage fluid was significantly higher in the needle lavage group than in the arthroscopic lavage group (P < .01). For both groups, the number of microspheres recovered in the first liter of lavage fluid represented a majority of the total microspheres collected and was significantly different from each subsequent liter collected (P < .01). The number of microspheres recovered did not differ between liters 2, 3, 4, and 5 within or between treatment groups. CONCLUSION: In this model, tarsocrural lavage with three 14 g needles was more effective at removing colored microspheres from the joint than arthroscopic lavage, suggesting that the number or placement of portals present may be more important than portal size and flow rate. No difference in microsphere recovery was seen with lavage volumes >1 L.

Correlation of pre-veterinary admissions criteria, intra-professional curriculum measures, AVMA-COE professional competency scores, and the NAVLE.

Data consisting of preadmission criteria scores, annual and final cumulative grade point averages (GPAs), grades from individual professional courses, American Veterinary Medical Association Council on Education (AVMA-COE) Competency scores, annual class rank, and North American Veterinary Licensing Exam (NAVLE) scores were collected on all graduating DVM students at Kansas State University in 2009 and 2010. Associations among the collected data were compared by Pearson correlation. Pre-veterinary admissions criteria infrequently correlated with annual GPAs of Years 1-3, rarely correlated with the AVMA-COE Competencies, and never correlated with the annual GPA of Year 4. Low positive correlations occurred between the NAVLE and the Verbal Graduate Record Examination (GRE) (r=.214), Total GRE (r=.171), and the mean GPA of pre-professional science courses (SGPA) (r=.236). Annual GPAs strongly correlated with didactic course scores. Annual GPAs and final class rank strongly correlated (mean r=-.849), and both strongly correlated with the NAVLE score (NAVLE: GPAs mean r=.628, NAVLE: final class rank r=-.714). Annual GPAs at the end of Years 1-4 weakly correlated or did not correlate with the AVMA-COE Competencies. The AVMA-COE Competencies weakly correlated with scores earned in didactic courses of Years 1-3. AVMA-COE Competencies were internally consistent (mean r=.796) but only moderately correlated with performance on the NAVLE (mean r=.319). Low correlations between admissions criteria and outcomes indicate a need to reevaluate admission criteria as predictors of school success. If the NAVLE remains the primary discriminator for veterinary licensure (and the gateway to professional activity), then the AVMA-COE Competencies should be refined to better improve and reflect the NAVLE, or the NAVLE examination should change to reflect AVMA-COE Competencies.

Public health campaign to promote hand hygiene before meals in a college of veterinary medicine.

Veterinary students can be exposed to environmental infectious agents in school that may include zoonotic pathogens. Encouraging effective hand hygiene can minimize the spread of zoonoses and promote public health and the One Health concept among veterinary students. The purpose of this study was to determine if a campaign could improve hand hygiene among veterinary students at extracurricular meetings serving meals. Nine Kansas State University College of Veterinary Medicine (KSU-CVM) extracurricular organizations participated in the study, sanitizer was provided at each meeting, and baseline hand-hygiene data were observed. A hand-hygiene opportunity was defined as any student observed to approach the buffet food line. Sanitizer use (yes/no) and gender (male/female) were recorded. Campaign interventions included a 3.5-minute educational video and a novel motivational poster. The video was presented to all first-year, second-year, and third-year veterinary students. Posters encouraging hand sanitization were displayed on doors and tables alongside sanitizers at each meeting. Observational hand-hygiene data were collected immediately after introduction of interventions and again 3 months later. Environmental sampling for presence of bacteria in and around meeting locations was also performed. Observed hand hygiene was lowest during baseline (11.0% ± 1.7), improved significantly post-intervention (48.8% ± 3.2), and remained improved at 3-month follow-up (33.5% ± 4.0). Females had higher probability of hand sanitizing (35.9% ± 2.2) than males (21.4% ± 2.4) (p<.01). Clostridium perfringens was isolated from 2/42 samples, and Salmonella spp. were isolated from 4/42 samples. A short-term public health campaign targeting veterinary students successfully improved hand hygiene before meals.

Level of and motivation for extracurricular activity are associated with academic performance in the veterinary curriculum.

The objectives of this project were to determine the number of school-sanctioned extracurricular opportunities available to veterinary students and characterize the policies of school administrations toward extracurricular involvement and academic standing. Further, we sought to describe the level of extracurricular involvement of veterinary students, determine the association between extracurricular activity involvement and academic performance, and determine the motivation for extracurricular involvement of veterinary students. Survey data were obtained from 18 associate deans of colleges of veterinary medicine regarding the number of extracurricular student organizations within their school and administrative recommendations regarding student involvement. Another survey was administered and responded to by 665 veterinary students enrolled in curricular years 1-3 at Kansas State University and Texas A&M University regarding their extracurricular involvement. Associate deans of 11 schools responded that they make formal or informal recommendations to students about extracurricular activities, workload, and academic priority (61.1%). In a multivariate model, students who participated two times per week or more had a significantly higher overall grade point average (GPA) than students participating once per week (p<.0500). Students for whom the primary reason for participation was networking or social enhancement had a significantly lower overall GPA than students for whom the primary reason was gaining new knowledge and skills (p<.0500). These results indicate that student extracurricular involvement is a consideration for administrators when counseling students in academic difficulty. Moderate levels of extracurricular involvement can contribute to the academic success of students, but students should temper their level of involvement based upon their own motivations.

Economic impact of mortality prediction by predictive model at first and second treatment for bovine respiratory disease.

OBJECTIVE: To evaluate a predictive model's ability to determine cattle mortality following first and second treatment for bovine respiratory disease and to understand the differences in net returns comparing predictive models to the status quo. METHODS: 2 boosted decision tree models were constructed, 1 using data known at first treatment and 1 with data known at second treatment. Then, the economic impact of each outcome (true positive, true negative, false positive, and false negative) was estimated using various market values to determine the net return per head of using the predictive model to determine which animals should be culled at treatment. This was compared to the status quo to determine the difference in net return. RESULTS: The models constructed for the prediction of mortality performed with moderate accuracy (areas under the curve > 0.7). The economic analysis found that the models at a high specificity (> 90%) could generate a positive net return in comparison to status quo. CONCLUSIONS: This study showed that predictive models may be a useful tool to make culling decisions and could result in positive net returns. CLINICAL RELEVANCE: Bovine respiratory disease is the costliest health condition experienced by cattle on feed. Feedyard record-keeping systems generate vast amounts of data that could be used in predictive models to make management decisions. It is essential to understand the accuracy of predictions made via machine learning. However, the economic impact of implementing predictive models in a feedyard will influence adoption.

Investigation into the impact of audience response devices on short- and long-term content retention.

Audience Response Systems (ARSs) may enhance short-term knowledge retention. Long-term knowledge retention is more difficult to demonstrate. According to previous studies, ARS questions requiring application of knowledge or peer interaction are more effective in maintaining student attention. The purpose of this study was to determine if peer discussion or individual-knowledge questions enhance short- and/or long-term knowledge retention. Third-year veterinary students responded to ARS questions posed in individual knowledge (n=3 questions) and peer discussion (n=3 questions) format from six different instructors. To test short-term memory, the same questions were delivered during the course examination (within 21 days). To test long-term retention, these questions were posed during a retention exercise (four months later). On the course examination, students had a higher (p<.01) probability (±SE) of correctly answering ARS individual-knowledge questions (93.8 ± 1.8%) compared to novel (previously unseen, non-ARS control) course examination questions (87.5 ± 3.1%), but the probability of correctly answering examination questions previously posed using ARS peer discussion format (89.5 ± 3.0%) did not differ from individual knowledge or novel examination questions. The positive impact of ARS-knowledge questions was not maintained through the retention exercise. Neither individual knowledge (70.5 ± 6.4%) nor peer-discussion questions (67.5 ± 6.9%) performed better on the retention exercise than the questions that appeared only on the course examination (68.6 ± 6.1%). Curricular strategies that emphasize content review may be more powerful than strategies that strengthen initial learning for long-term content retention.

Evaluation of predictive models to determine final outcome for feedlot cattle based on information available at first treatment for bovine respiratory disease.

OBJECTIVE: To evaluate predictive model ability to determine whether an animal finished the feeding period using data known at first treatment for bovine respiratory disease (BRD). Additional comparisons evaluated the potential benefits of predictions by adding weather data, utilizing balancing techniques, and creating models for individual feedyards. ANIMALS: This retrospective study included animal, pen, and feedyard data from 12 US feedyards from 2016 to 2021. The final dataset consisted of 96,382 BRD cases of which 14.2% did not finish the feeding phase. PROCEDURES: Five predictive models were trained and underwent threshold probability adjustment to maximize F1 score. Model performance was evaluated using accuracy, sensitivity specificity, positive and negative predictive values, and area under the receiver operating characteristics curve (AUC). RESULTS: Overall, model performance was low with a median AUC value of 0.675. The addition of weather data had little effect on AUC but resulted in more variation in sensitivity and specificity. Resampling the dataset had a limited effect on performance. Individual feedlot models had higher AUC values than others with the decision tree typically performing best in most feedyards. CLINICAL RELEVANCE: Results indicated some utility of predictive models evaluating BRD cases to predict cattle that did not finish the feeding phase. These models could be valuable in assisting health providers making decisions on individual cases.

Determination of Behavioral Changes Associated with Bovine Respiratory Disease in Australian Feedlots.

Accurately identifying bovine respiratory disease is challenging in feedlots, and previous studies suggest behavioral monitoring is important. The study objective was to describe individual differences in physical activity (distance traveled), feeding/watering patterns (proximity to feed and water), and social behavior (average cattle within 3 m) when associated with health status in commercially raised beef cattle during the first 28 days on feed. Data from a previous Australian feedlot study monitoring cattle behavior and associated health outcomes were analyzed. Health status categories were generated for all cattle, and each animal was categorized as known healthy (HLTH), known diseased (SICK), or intermediate/uncertain (INTR). The INTR animals were excluded from the final analysis. Key findings included: differentiation in activity between SICK (n = 138) and HLTH (n = 1508) cattle dependent on time of day, SICK cattle spending more time in water and feeding zones early in the feeding phase (<6 days on feed), SICK cattle spending more time in the water and feeding zone during the overnight hours, and SICK cattle spending more time in groups early in the feeding phase but more time in isolation after the first week on feed. Results illustrate behavioral data were associated with important health outcomes.

Evaluation of First Treatment Timing, Fatal Disease Onset, and Days from First Treatment to Death Associated with Bovine Respiratory Disease in Feedlot Cattle.

Bovine respiratory disease (BRD) is a frequent beef cattle syndrome. Improved understanding of the timing of BRD events, including subsequent deleterious outcomes, promotes efficient resource allocation. This study's objective was to determine differences in timing distributions of initial BRD treatments (Tx1), days to death after initial treatment (DTD), and days after arrival to fatal disease onset (FDO). Individual animal records for the first BRD treatment (n = 301,721) or BRD mortality (n = 19,332) were received from 25 feed yards. A subset of data (318-363 kg; steers/heifers) was created and Wasserstein distances were used to compare temporal distributions of Tx1, FDO, and DTD across genders (steers/heifers) and the quarter of arrival. Disease frequency varied by quarter with the greatest Wasserstein distances observed between Q2 and Q3 and between Q2 and Q4. Cattle arriving in Q3 and Q4 had earlier Tx1 events than in Q2. Evaluating FDO and DTD revealed the greatest Wasserstein distance between cattle arriving in Q2 and Q4, with cattle arriving in Q2 having later events. Distributions of FDO varied by gender and quarter and typically had wide distributions with the largest 25-75% quartiles ranging from 20 to 80 days (heifers arriving in Q2). The DTD had right-skewed distributions with 25% of cases occurring by days 3-4 post-treatment. Results illustrate temporal disease and outcome patterns are largely right-skewed and may not be well represented by simple arithmetic means. Knowledge of typical temporal patterns allows cattle health managers to focus disease control efforts on the correct groups of cattle at the appropriate time.

No evidence for a negative association between bovine leukemia virus status and fertility in Kansas beef herds: a cross-sectional study.

OBJECTIVE: Determine the association between bovine leukemia virus (BLV) status and fertility in beef cows. BLV-status was defined using 3 different testing strategies (ELISA-, quantitative polymerase chain reaction- [qPCR], and high proviral load [PVL]-status). Fertility was defined as the overall probability of pregnancy as well as the probability of becoming pregnant in the first 21 days of the breeding season. ANIMALS: Convenience sample of 2,820 cows from 43 beef herds. PROCEDURES: The association of BLV-status with the probability of becoming pregnant was evaluated with a multivariable logistic regression analysis that used pregnancy status as a binary outcome, herd nested within ranch as a random effect, and BLV-status (ELISA-, qPCR-, and PVL-status as separate models) and potential covariates (eg, age, Body Condition Score [BCS] category, and interactions) as fixed effects. RESULTS: Raw data revealed that 55% (1,552/2,820) of cows were classified as BLV-positive by ELISA, and 95.3% (41/43) of herds had a least 1 ELISA-positive cow. Classification as BLV ELISA-positive was positively associated with the probability of being pregnant; however, when qPCR or PVL were used to classify BLV-status, there was no association with the probability of being pregnant. None of the methods of classifying BLV-status were associated with the probability of becoming pregnant in the first 21 days of the breeding season. CLINICAL RELEVANCE: This study did not find evidence that testing beef cows for BLV-status using ELISA, qPCR, or a cut-off of 0.9 PVL and removing test-positive cows will improve cowherd fertility as described by the probability of becoming pregnant during the breeding season or becoming pregnant during the first 21 days of the breeding season.

Image Classification and Automated Machine Learning to Classify Lung Pathologies in Deceased Feedlot Cattle.

Bovine respiratory disease (BRD) and acute interstitial pneumonia (AIP) are the main reported respiratory syndromes (RSs) causing significant morbidity and mortality in feedlot cattle. Recently, bronchopneumonia with an interstitial pattern (BIP) was described as a concerning emerging feedlot lung disease. Necropsies are imperative to assist lung disease diagnosis and pinpoint feedlot management sectors that require improvement. However, necropsies can be logistically challenging due to location and veterinarians' time constraints. Technology advances allow image collection for veterinarians' asynchronous evaluation, thereby reducing challenges. This study's goal was to develop image classification models using machine learning to determine RS diagnostic accuracy in right lateral necropsied feedlot cattle lungs. Unaltered and cropped lung images were labeled using gross and histopathology diagnoses generating four datasets: unaltered lung images labeled with gross diagnoses, unaltered lung images labeled with histopathological diagnoses, cropped images labeled with gross diagnoses, and cropped images labeled with histopathological diagnoses. Datasets were exported to create image classification models, and a best trial was selected for each model based on accuracy. Gross diagnoses accuracies ranged from 39 to 41% for unaltered and cropped images. Labeling images with histopathology diagnoses did not improve average accuracies; 34-38% for unaltered and cropped images. Moderately high sensitivities were attained for BIP (60-100%) and BRD (20-69%) compared to AIP (0-23%). The models developed still require fine-tuning; however, they are the first step towards assisting veterinarians' lung diseases diagnostics in field necropsies.

Epidemiological Factors Associated with Gross Diagnosis of Pulmonary Pathology in Feedyard Mortalities.

Respiratory disease continues to be the major cause of mortality in feedyard cattle, with bronchopneumonia (BP) and acute interstitial pneumonia (AIP) as the two most common syndromes. Recent studies described a combination of these pathological lesions with the presence of AIP in the caudodorsal lungs and BP in the cranioventral lungs of necropsied cattle. This pulmonary pathology has been described as bronchopneumonia with an interstitial pneumonia (BIP). The epidemiological characteristics of BIP in U.S. feedyard cattle are yet to be described. This study's objectives were to describe the agreement between feedyard clinical and necropsy gross diagnosis and to characterize epidemiological factors associated with four gross pulmonary diagnoses (AIP, BIP, BP, and Normal pulmonary tissue) observed during feedyard cattle necropsies. Systemic necropsies were performed at six feedyards in U.S. high plains region, and gross pulmonary diagnoses were established. Historical data were added to the dataset, including sex, days on feed at death (DOFDEATH), arrival weight, treatment count, and feedyard diagnosis. Generalized linear models were used to evaluate epidemiological factors associated with the probability of each pulmonary pathology. Comparing feedyard clinical diagnosis with gross pathological diagnosis revealed relatively low agreement and the frequency of agreement varied by diagnosis. The likelihood of AIP at necropsy was higher for heifers than steers and in the 100-150 DOFDEATH category compared with the 0-50 DOFDEATH (p = 0.05). The likelihood of BIP increased after the first treatment, whereas the DOFDEATH 0-50 category had a lower likelihood compared with the 150-200 category (p = 0.05). These findings highlight the importance of necropsy for final diagnosis and can aid the development of future diagnosis and therapeutic protocols for pulmonary diseases.

Retrospective analysis of risk and timing of death from right heart failure in United States and Canadian feedlot necropsied cattle.

OBJECTIVE: To evaluate the risk and timing of right heart failure (RHF) in feedlot cattle. ANIMALS: Study population consisted of 1,717,356 cattle (5,527 cohorts) in 13 US and Canadian feedlots. There were 1,336 RHF diagnosed at necropsy. PROCEDURES: Multivariable models were utilized to evaluate risk and timing of RHF death. RESULTS: Arrival year was associated with RHF and was influenced by arrival quarter on the magnitude of risk of RHF (P < .01), but no linear increase over years was identified. The impact of feedlot elevation on RHF was modified by breed (beef, dairy, or dairy-cross; P < .01) with beef cattle in the highest elevation category having 0.54 times the risk of RHF as dairy cattle in the same elevation category (LCL = 0.31; UCL = 0.962). Cattle that died due to RHF and were treated for bovine respiratory disease died 11 days (LCL = 1.33, UCL = 20.2 days) sooner than cattle never treated for bovine respiratory disease (P = .03). Cattle breed was associated with RHF timing (P = .01), and dairy-cross cattle RHF cases died approximately 37 days earlier (SE = 13.0 days; P = .01) compared to beef cattle. CLINICAL RELEVANCE: This research showed demographic factors associated with RHF and their respective influence on risk and timing of RHF. Risk rates of RHF were similar to previous research. This could allow for comparisons across different feedlot populations, using different diagnoses at necropsy and RHF risk/rates do not appear to be increasing.

Nasopharyngeal Bacterial Prevalence and Microbial Diversity at First Treatment for Bovine Respiratory Disease (BRD) and Its Associations with Health and Mortality Outcomes in Feedyard Cattle.

Bovine respiratory disease (BRD) is an economically important disease in feedyards influencing both animal welfare and antimicrobial utilization. Major pathogens associated with BRD have been identified in previous research, but little information is available on the relationship between nasopharyngeal microbiota and health outcomes. The objective of this study was to identify potential associations between nasopharyngeal microbiota and antimicrobial resistance patterns of clinical cases that lived or died compared to non-diseased controls. Enrolled animals were subdivided based on clinical disease status and case outcome (subsequent mortality). Deep nasopharyngeal swabs were collected on enrolled animals and submitted for bacterial isolation, antimicrobial susceptibility determination, and metagenomics analysis. Enrolled cattle were represented in three groups: animals at first treatment for BRD that subsequently died (BRDM, n = 9), animals at first treatment for BRD that subsequently lived (BRDL, n = 15), and animals that were never treated for BRD during the feeding phase (CONT, n = 11). Antimicrobial resistance patterns for Pasteurella multocida illustrated cattle in each outcome category had isolates that were pan-susceptible or only showed resistance to oxytetracycline. The relative abundance of species and genera illustrated few differences among the three outcomes. Higher alpha diversity was identified in BRDL compared to CONT at the species level, and both BRDL and BRDM showed increased alpha diversity compared to CONT at the general level. Overall, this work illustrated nasopharyngeal microbiota showed relatively few differences among BRD cases that lived or died compared to animals without BRD.

Determining Frequency of Common Pulmonary Gross and Histopathological Findings in Feedyard Fatalities.

Pulmonary disease is often associated with feedlot cattle mortality, and the most common syndromes include bronchopneumonia, acute interstitial pneumonia, and bronchopneumonia with an interstitial pneumonia. The study objective was to utilize gross necropsy and histopathology to determine the frequency of pulmonary lesions from three major syndromes and agreement between gross and histopathological diagnosis. A cross sectional, observational study was performed at six U.S. feedyards using a full systematic necropsy to assess mortalities during summer 2022. A subset of mortalities had four lung samples submitted for histopathological diagnosis. Gross necropsy was performed on 417 mortalities, 402 received a gross diagnosis and 189 had a histopathological diagnosis. Descriptive statistics were used to evaluate pulmonary diagnosis frequency based on method (gross/histopathology), and generalized linear mixed models were used to evaluate agreement between histopathological and gross diagnoses. Using gross diagnosis, bronchopneumonia represented 36.6% of cases with acute interstitial pneumonia and bronchopneumonia with an interstitial pneumonia representing 10.0% and 35.8%, respectively. Results identified bronchopneumonia with an interstitial pneumonia as a frequent syndrome which has only been recently reported. Histopathological diagnosis had similar findings; bronchopneumonia represented 32.3% of cases, with acute interstitial pneumonia and bronchopneumonia with an interstitial pneumonia representing 12.2% and 36.0%, respectively. Histopathological diagnosis tended (p-VALUE = 0.06) to be associated with gross diagnosis. Pulmonary disease was common and both diagnostic modalities illustrated three primary syndromes: bronchopneumonia, acute interstitial pneumonia, and bronchopneumonia with an interstitial pneumonia with similar frequencies. Improved understanding of pulmonary pathology can be valuable for evaluating and adjusting therapeutic interventions.