Bo Norby

Analgesic drug administration and attitudes about analgesia in cattle among bovine practitioners in the United States

OBJECTIVE To determine current attitudes and practices related to pain and analgesia in cattle among US veterinarians in bovine practice and to identify factors associated with these attitudes and practices. DESIGN Web-based survey. Sample-3,019 US members of the American Association of Bovine Practitioners (AABP) with e-mail addresses. PROCEDURES Veterinarians were invited via e-mail to participate in a Web-based survey. Respondents replied to questions related to pain and analgesia and supplied personal, professional, and demographic information. Descriptive statistical analysis was performed, and associations among various factors were examined. RESULTS 666 surveys (25.5% response rate) were analyzed. Among common procedures and medical conditions of cattle listed on the survey, castration of dairy calves < 6 months old was subjectively estimated as causing the least pain; abdominal surgery, toxic mastitis, and dehorning of calves > 6 months old were assessed as causing the greatest pain. Respondents reported not providing analgesic drugs to approximately 70% of calves castrated at < 6 months of age. The most commonly administered analgesics were NSAIDs, local anesthetics, and α(2)-adrenergic receptor agonists. Significant associations were detected among respondent characteristics and pain ratings, percentages of cattle treated, and opinions regarding analgesia. CONCLUSIONS AND CLINICAL RELEVANCE Results provide information on current attitudes and practices related to pain and analgesia in cattle among US veterinarians in bovine practice and can be considered in the development of policies and protocols for pain management in cattle. These data can be compared with those of future studies to examine changes over time.

Clostridium difficile in retail meat and processing plants in Texas

The incidence and severity of disease associated with toxigenic Clostridium difficile have increased in hospitals in North America from the emergence of newer, more virulent strains. Toxigenic C. difficile has been isolated from food animals and retail meat with potential implications of transfer to human beings. The objective of the present study was to determine the prevalence of C. difficile in pork from sausage manufacturing plants and retail meat in Texas. Twenty-three C. difficile isolates were detected from 243 meat samples (9.5%) from 3 sausage-manufacturing plants and 5 retail meat outlets from 2004 to 2009. Twenty-two isolates were positive for toxins A, B, and binary toxin, and were characterized as toxinotype V, PFGE type-NAP7, or “NAP7-variant.” Susceptibilities to 11 antimicrobial agents in the current study were similar to those reported previously for toxinotype V isolates, although the results suggested somewhat reduced resistance than reported for other meat, animal, or human clinical toxinotype V isolates.

Quantification of the blaCMY-2 in feces from beef feedlot cattle administered three different doses of ceftiofur in a longitudinal controlled field trial.

The objective of this longitudinal controlled trial was to quantitatively compare carriage of a gene encoding for ceftiofur-resistance (bla(CMY-2)), standardized to a reference gene (16SrRNA), among total community DNA extracted from fecal samples collected from cattle treated with three different dose regimens of ceftiofur crystalline-free acid (CCFA) versus those untreated (controls). Sixty-one steers were assigned to three treatment regimens and housed in six pens. In each pen, five steers were treated and five were controls (one of the pens had six controls). CCFA administration was as follows: two-thirds dose treatment (4.4 mg/kg, on day 0), single-dose treatment (6.6 mg/kg, on day 0), and three-dose treatment (6.6 mg/kg, on days 0, 6, and 13). Fecal samples were collected on days 0, 3, 7, 10, 14, 18, 21, and 28. The gene copy numbers/gram of feces for bla(CMY-2) and 16SrRNA were determined in total community DNA samples using quantitative real-time PCR. The relationships between the quantities of standardized bla(CMY-2), nonstandardized bla(CMY-2), and nonstandardized 16SrRNA, and the explanatory variables (treatment, time, and treatment x time) were assessed using repeated measures mixed models. There were significant differences in each of the three models with respect to each explanatory variable. Overall, while steers administered three doses and two-thirds dose of CCFA had significantly higher quantities of nonstandardized bla(CMY-2) than controls, the standardized values were lower. The administration of CCFA in feedlot cattle may provide selection pressure favoring higher levels of bla(CMY-2) carriage, but this may also lead to concurrent reductions in the total bacterial population (as reflected by lowered 16SrRNA) during the treatment period.

Antimicrobial susceptibility of enteric bacteria recovered from feedlot cattle administered chlortetracycline in feed

OBJECTIVE To evaluate administration of chlortetracycline in feed of cattle as a method to select for tetracycline resistance among enteric bacteria in feedlot settings. ANIMALS 20 steers. PROCEDURES Steers were randomly assigned to an exposed cohort (n = 10) or an unexposed cohort (control cohort; 10). Chlortetracycline (22 mg/kg) in cottonseed meal was administered to the exposed cohort on days 0 through 4, 6 through 10, and 12 through 16. The control cohort was administered only cottonseed meal. Fecal samples were collected from 16 steers on days -7, 0, 2, 6, 8, 12, 14, 19, 22, 26, and 33, and Escherichia coli and Enterococcus spp were isolated. Minimum inhibitory concentration (MIC) of selected antimicrobials was estimated. RESULTS Overall, 56.0% and 31.4% of E coli and Enterococcus isolates, respectively, were resistant to tetracycline. Exposure to chlortetracycline was associated with a significant temporary increase in log(2) MIC for both genera but returned to preexposure values by day 33. Averaged across time, the proportion of tetracycline-resistant E coli and Enterococcus isolates was significantly greater in exposed than in unexposed steers. Although all ceftiofur-resistant E coli isolates were coresistant to tetracycline, exposure to chlortetracycline led to a significant decrease in the proportion of E coli resistant to ceftiofur during exposure. CONCLUSIONS AND CLINICAL RELEVANCE Exposure to chlortetracycline was associated with a temporary increase in the likelihood of recovering resistant bacteria. Exposure to chlortetracycline decreased the likelihood of recovering ceftiofur-resistant E coli isolates, even though isolates were coresistant to tetracycline. These findings warrant further investigation.

Options for the control of bovine leukemia virus in dairy cattle

The subclinical impact of bovine leukemia virus (BLV) on the sustainability of the US dairy industry is only now being fully recognized. Findings of recent longitudinal studies conducted in Michigan dairy herds were consistent with the results of previous studies in showing that within-herd prevalence of BLV-infected cattle was negatively associated with milk production and cow longevity. Risk factors relating to routes of hematogenous transmission such as the use of shared hypodermic needles, shared reproductive examination sleeves, and natural breeding were associated with BLV within-herd prevalence. Few US dairy producers know the prevalence of BLV-infected cattle in their herds or are aware of the insidious economic impact of BLV or the options for BLV control. As an increasing number of countries eradicate BLV from their cattle populations, restrictions on the movement of US cattle and cattle products will likely increase. Veterinarians should be aware of recent developments for screening serum and milk samples for antibodies against BLV and the results of research regarding the economic impact of BLV so they can advise their dairy clients of available alternatives for monitoring and controlling BLV infection.

Utility of Endoscopic Biopsies of the Duodenum and Ileum for Diagnosis of Inflammatory Bowel Disease and Small Cell Lymphoma in Cats

BACKGROUND Endoscopic duodenal biopsies are relatively convenient, minimally invasive tests for infiltrative intestinal disorders of cats. Ileal endoscopic biopsies might not be performed because of technical difficulty and effort required to prepare the colon. It is not known whether or not histopathology of feline duodenal and ileal biopsies for detection of inflammatory bowel disease (IBD) and small cell lymphoma (SC-LSA) provides comparable results. OBJECTIVES To evaluate the agreement between endoscopic biopsies of duodenum and ileum in cats with IBD and SC-LSA. ANIMALS Seventy client-owned cats with gastrointestinal disease and adequate duodenal and ileal tissue biopsies obtained endoscopically. METHODS Retrospective study: Search of medical records of cats with enteropathy and endoscopy. Samples were blinded and re-evaluated by single pathologist (JM) for quality, number of biopsies, and diagnosis according to WSAVA standards. Agreement of IBD and SC-LSA diagnoses among biopsy sites assessed using Cohens Kappa. RESULTS Eighteen of 70 cats (26%) were diagnosed with SC-LSA in duodenum, ileum, or both. Of these 18 cats, 7 (39%) were diagnosed with only duodenal SC-LSA, 8 (44%) were diagnosed with only ileal SC-LSA, and 3 (17%) had SC-LSA in both duodenum and ileum. There was poor agreement on diagnosis between duodenal and ileal biopsies (kappa = 0.23). CONCLUSIONS AND CLINICAL IMPORTANCE Although review by a single pathologist remains a limitation of this study, results suggest that there is a population of cats in which diagnosis of SC-LSA can be found only by evaluation of ileal biopsies. Clinicians should consider performing both upper and lower GI endoscopic biopsies in cats with infiltrative small bowel disease.

Associations between dietary factors and pancreatitis in dogs

OBJECTIVE To estimate associations between dietary factors and pancreatitis in dogs. Design-Retrospective case-control study. ANIMALS 198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis. PROCEDURES Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatments, duration of hospitalization, and discharge status was extracted from medical records. Information on dietary intake, signalment, weight, and medical, surgical, and environmental history was collected through a telephone questionnaire. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals. RESULTS On the basis of information extracted from the medical record, ingesting unusual food items (OR, 4.3) increased the odds of pancreatitis. On the basis of information gathered through the telephone questionnaire, ingesting unusual food items (OR, 6.1), ingesting table scraps the week before diagnosis (OR, 2.2) or throughout life (OR, 2.2), and getting into the trash (OR, 13.2) increased the odds of pancreatitis. Multivariable modeling indicated that reporting exposure to > or = 1 dietary factor during the telephone questionnaire (OR, 2.6), being overweight (OR, 1.3) or neutered (OR, 3.6), previous surgery other than neutering (OR, 21.1), and the interaction between neuter status and previous surgery other than neutering (OR, 0.1) were associated with the odds of pancreatitis. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that dietary factors, being neutered, and previous surgery other than neutering increased the odds of pancreatitis in dogs.

The sensitivity of gross necropsy, caudal fold and comparative cervical tests for the diagnosis of bovine tuberculosis

Bovine tuberculosis (bTb) was diagnosed in 22 cattle herds in the northeast corner of Michigans lower peninsula. Of these 22 herds, 494 animals in 7 herds were examined by gross necropsy, histopathologic exam, mycobacterial culture, and polymerase chain reaction (PCR) assay performed only on samples that were histologically compatible for bTb. Results of culture and PCR assay interpreted in parallel were used as the reference test for calculation of the sensitivity of 1) the caudal fold test (CFT), 2) the caudal fold and comparative cervical skin tests used in series (CFTCCTSER), and 3) gross necropsy. Mycobacterium bovis was isolated from 43 animals. Using all 7 herds, the sensitivities of the CFT, the CFTCCTSER, and gross necropsy were 93.02%, 88.37%, and 86.05%, respectively. When the data were stratified by low- and moderate-prevalence herds, the sensitivities were 83.33%, 75.0%, and 83.33% in low-prevalence herds and 96.77%, 93.55%, and 87.10% in moderate-prevalence herds. The sensitivities of the 2 skin tests were slightly higher when 2 or more gross lesions were present, and the sensitivity of gross necropsy was significantly higher (P = 0.049). The sensitivity of the CFT was found to be notably higher than most estimates in other studies; however, a direct comparison was not possible because the amount of purified protein derivative and the reference methods were different in this study compared with other published studies. Although the sensitivities are high, 2 of the 7 herds (29%) would have had 1 or more positive animals left in the herd if a test-and-removal program had been used. This suggests that when positive herds are identified, selective culling of skin test reactors is a less acceptable disease control strategy than is complete depopulation.

Bovine leukemia virus and cow longevity in Michigan dairy herds

To determine the association between infection with bovine leukemia virus (BLV) and cow longevity, a stratified random sample of 3,849 Holsteins in 112 Michigan dairy herds was followed for an average of 597 d following testing for BLV antibodies with an ELISA milk test. The hazard ratio of 1.23 indicates that BLV-positive cows were 23% more likely than their BLV-negative herd mates to die or be culled during the monitoring period. This result is adjusted for lactation number, which is also positively associated with an increased risk of leaving the herd. Because herd was included in models, the effect of BLV ELISA on cow longevity was a within-herd comparison in which BLV-infected cattle were compared with their uninfected herd mates. The analysis of 4 ELISA optical density (OD) groups demonstrated a dose response such that cows with higher OD values had decreased survival compared with cows with lower OD values. Cows with OD values above 0.5 were at 40% greater risk of dying or being culled than were their uninfected herd mates. These results support the contention that the association of BLV with cow longevity, when added to other economic impacts, may warrant the control of BLV in our US dairy cow population.

Longitudinal Study of Antimicrobial Resistance among Escherichia coli Isolates from Integrated Multisite Cohorts of Humans and Swine

ABSTRACT In a 3-year longitudinal study, we examined the relationship between the seasonal prevalence of antimicrobial-resistant (AR) Escherichia coli isolates from human wastewater and swine fecal samples and the following risk factors: the host species, the production type (swine), the vocation (human swine workers, non-swine workers, and slaughter plant workers), and the season, in a multisite, vertically integrated swine and human population representative of a closed agri-food system. Human and swine E. coli (n = 4,048 and 3,429, respectively) isolates from wastewater and fecal samples were tested for antimicrobial susceptibility, using the Sensititre broth microdilution system. There were significant (P < 0.05) differences among AR E. coli prevalence levels of (i) the host species, in which swine isolates were at higher risk for resistance to tetracycline, kanamycin, ceftiofur, gentamicin, streptomycin, chloramphenicol, sulfisoxazole, and ampicillin; (ii) the swine production group, in which purchased boars, nursery piglets, and breeding boars isolates had a higher risk of resistance to streptomycin and tetracycline; and iii) the vocation cohorts, in which swine worker cohort isolates exhibited lower sulfisoxazole and cefoxitin prevalence than the non-swine worker cohorts, while the slaughter plant worker cohort isolates exhibited elevated cefoxitin prevalence compared to that of non-swine workers. While a high variability was observed among seasonal samples over the 3-year period, no significant temporal trends were apparent. There were significant differences in the prevalence levels of multidrug-resistant isolates between host species, with swine at a higher risk of carrying multidrug-resistant strains than humans. Considering vocation, slaughter plant workers were at higher risk of exhibiting multidrug-resistant E. coli than non-swine workers.