Odds of a diagnosis of CVM were greater in young horses and horses of specific breeds. Detection of gait asymmetry and cervical hyperesthesia were frequently reported in association with CVM. Accurate diagnosis of lesions associated with CVM by use of radiography and myelography can be challenging.

BackgroundFour sampling techniques commonly are used for antemortem identification of pathogens from cattle with bovine respiratory disease (BRD): the nasal swab (NS), guarded nasopharyngeal swab (NPS), bronchoalveolar lavage (BAL), and transtracheal wash (TTW). Agreement among these methods has not been well characterized.ObjectiveTo evaluate agreement among TTW and NS, NPS, or BAL for identification of viral and bacterial pathogens in dairy calves with BRD.AnimalsOne hundred dairy calves with naturally acquired BRD.MethodsCalves were sampled by all 4 methods. Viral agents were identified by real‐time RT‐PCR, bacteria were identified by aerobic culture, and Mycoplasma bovis (M. bovis) isolates were speciated by PCR. Agreement among TTW and NS, NPS, or BAL was evaluated by calculating the kappa statistic and percent positive agreement. McNemar's exact test was used to compare the proportions of positive results.ResultsAgreement among TTW and NS, TTW and NPS, and TTW and BAL, was very good for identification of P. multocida, M. haemolytica, and M. bovis. For bovine respiratory syncytial virus (BRSV), agreement with TTW was moderate for NS, good for NPS, and very good for BAL. For bovine coronavirus (BCV), agreement with TTW was moderate for NS and NPS, and good for BAL. McNemar's test was significant only for BCV, indicating that for this pathogen the proportion of positive results from NS and NPS could not be considered comparable to TTW.Conclusions and Clinical ImportanceThis study provides guidance for veterinarians selecting diagnostic tests for antemortem identification of pathogens associated with BRD.

Bovine respiratory disease (BRD) is the most common cause of morbidity and mortality in North American beef cattle. Mannheimia haemolytica is the bacterial pathogen most often isolated from cattle with BRD, and the prevalence of antimicrobial resistance (AMR) in this organism has increased in recent years. Antimicrobials are commonly used to prevent BRD in cattle at high risk of developing BRD; however, recent work would suggest that this practice might be one factor contributing to the increased prevalence of AMR in M. haemolytica. We hypothesized that the administration of the short-acting fluoroquinolone, enrofloxacin, would be just as effective as the long-acting triamilide, tulathromycin, in preventing BRD but would be less likely to select for AMR M. haemolytica in stocker calves at high risk of developing BRD. Three hundred forty-one stocker calves were enrolled in the study with 172 calves in 4 pens being randomly assigned to treatment with enrofloxacin and 169 calves in 4 pens randomly assigned to treatment with tulathromycin. Calves within each treatment group were allocated to one of 4 replicate pens based on the week of enrollment. Of calves receiving enrofloxacin, 33.7% required treatment for BRD at least once within 45 d after arrival, compared with 18.3% of calves receiving tulathromycin (P = 0.040). The percentages of calves that required more than one treatment for BRD within 45 d after arrival did not differ statistically for those receiving enrofloxacin compared with those receiving tulathromycin (10.5% and 4.7%, respectively; P = 0.107) Likewise, the percentages of calves that died during the 45-d follow-up period did not differ for those receiving enrofloxacin compared with those receiving tulathromycin (12.2% and 10.1%, respectively; P = 0.592). Mannheimia haemolytica was cultured from 11% of calves sampled at arrival and from 50% of calves sampled at revaccination 14 to 17 d later. There was a significanst effect of sampling time on the proportion of calves carrying multidrug-resistant (MDR) isolates, with calves having a higher prevalence of MDR isolates at revaccination than arrival (100% vs. 13%; P < 0.001). Future research evaluating the impact of MDR on response to antimicrobial therapy is necessary.

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle. () is the bacterial pathogen most frequently isolated from cattle with BRD and the prevalence of antimicrobial resistance in this pathogen has been increasing. Administration of antimicrobials to prevent BRD is commonplace in stocker cattle, but the impact of this practice on emergence of resistance in is unknown. High risk, sale barn origin bull and steer calves ( = 169) were transported to a stocker facility in central Georgia and sampled via deep nasopharyngeal swab (NPS) at arrival processing. All calves received the macrolide antimicrobial tulathromycin (2.5 mg/kg subcutaneously) at arrival processing. A second NPS was collected from each calf 10 to 14 d after arrival. The occasional calves diagnosed and treated for BRD prior to 10 to 14 d were swabbed and cultured prior to treatment. Swabs were submitted for culture and antimicrobial susceptibility testing using the Kirby-Bauer disk diffusion method. Of the 169 cattle enrolled, 27 (16.0%) were culture positive for at arrival processing and of these, a multi-drug resistant (MDR) strain of was detected in 1 (3.7%). In contrast, 123 (72.8%) cattle were culture positive for at second sampling and of these, a MDR strain of was detected in 122 (99.2%). The proportions of cattle culture positive for and positive for MDR at arrival processing and at second sampling were significantly different ( < 0.001). At the level of the individual bacterial isolate, 366 individual isolates were collected from the calves at the time of the second sampling. Of these isolates, 361 (98.6%) were intermediate or resistant to all macrolides tested (tilmicosin, gamithromycin, tulathromycin) and the fluoroquinolone enrofloxacin. In addition, 254 isolates (69.4%) were intermediate or resistant to florfenicol and 4 (1.1%) were intermediate or resistant to ceftiofur. There was a significant difference in the proportion of isolates resistant to all of the drug classes except cephalosporins at arrival processing versus second sampling ( < 0.001). Our results show that there was an increase in the proportion of calves positive for from arrival processing to second sampling, and that there was an increase in the proportion of calves that had MDR strains of detected from arrival processing to second sampling. More research is needed to understand the role of metaphylaxis on MDR in and the impact of MDR on morbidity and mortality in stocker cattle.

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