Increased susceptibility of lead-exposed swine to Salmonella choleraesuis var kunzendorf.

The effect of oral subclinical lead exposure on the susceptibility of swine to Salmonella choleraesuis var kunzendorf was studied in two experiments. In experiment 1, 18 pigs were exposed to lead acetate and 18 pigs were exposed to sodium acetate for 1, 2, or 3 weeks and then challenge exposed intraperitoneally. In experiment 2, 8 pigs were exposed to lead chloride for 2 weeks, 8 pigs were exposed to lead chloride for 1 week, and 8 pigs were exposed to sodium chloride for 2 weeks. These pigs were then challenge exposed orally. Only one pig (sodium acetate-exposed) died during experiment 1, but clinical signs were more severe in sodium acetate-exposed than in lead acetate-exposed animals. In experiment 2, 93.6% of the lead-exposed pigs died, whereas control pigs had 50.0% mortality. In experiment 2, clinical signs were more severe in lead-exposed pigs, and bacteria were more widespread in the tissues of these animals. Significant reductions of beta- or gamma-globulin concentrations or of agglutinating antibody titers were not observed in lead-exposed pigs in either of the trials. Possible mechanisms of the increased susceptibility in lead-exposed pigs of experiment 2 are discussed.