How to cite this article: Vet. Res. (2009) 40:02
DOI: 10.1051/vetres:2008040

Potential associations between fecal shedding of Salmonella in feedlot cattle treated for apparent respiratory disease and subsequent adverse health outcomes

Mohammad Jahangir Alam¹, David G. Renter¹, Samuel E. Ives², Daniel U. Thomson³, Michael W. Sanderson³, Larry C. Hollis⁴ and Tiruvoor G. Nagaraja<sup>1

1</sup>  Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, 66506 USA
²  Cactus Research, Ltd., 12100 Cactus Feeders Road, Cactus, Texas, 79013 USA
³  Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, 66506 USA
⁴  Department of Animal Sciences and Industry, College of Agriculture, Kansas State University, Manhattan, Kansas, 66506 USA

Received 19 March 2008; accepted 22 September 2008; published online 27 September 2008

Abstract - A prospective cohort study was used to assess whether Salmonella fecal shedding in commercial feedlot cattle treated with antimicrobials for respiratory disease was associated with subsequent adverse health outcomes. Feces were collected per rectum from cattle that were examined for apparent respiratory disease, had a rectal temperature 40 °C, and subsequently received antimicrobial treatment. Salmonella were recovered from 918 (73.7%) of 1 245 fecal samples and weekly prevalence estimates ranged from 49 to 100% over the 3-month study. Genotypic and phenotypic characteristics of Salmonella strains in the population were determined. Serogroup E Salmonella were most common (73.3%), followed by C1 (11.0%), C3 (8.6%), and B (1.1%). Predominant serotypes were Orion (46.5%), Anatum (19.8%), Kentucky (8.7%), Montevideo (7.5%), and Senftenberg (4.9%). Few isolates (36/918) were positive for antimicrobial resistance-associated integron gene intI1. Phenotypic susceptibility was associated with isolate intI1 status. Crude re-pull, re-treatment and case fatality risks were higher for cattle that were Salmonella-positive versus -negative at initial treatment, but not statistically different on multivariable analysis. However, case fatality risk was higher for cattle shedding Group B Salmonella than for cattle shedding other serogroups. Lots (groups) with a higher Salmonella prevalence at first treatment had a higher proportion of mortalities occur in a hospital pen, higher overall re-treatment risks, and were more likely to be sampled later in the study. Results indicate a high prevalence of Salmonella in this population of cattle treated for apparent respiratory disease, but that effects associated with clinical outcomes may depend on the Salmonella strain.

Key words: Salmonella / bovine respiratory disease / feedlot / cattle

Corresponding author: drenter@vet.k-state.edu

© INRA, EDP Sciences 2008