Investigation of a chronic inflammation model in swine

Previous research demonstrated slow‐release lipopolysaccharide (LPS) pellets could induce a chronic inflammatory response in rodents. The objective of this preliminary study was to translate this rodent model of chronic inflammation into swine. A dose‐response study with repeated measures was performed using 12 barrows (~ 100 kg; three per group). The four treatments groups were: non‐surgical controls, placebo (pellet with matrix only), and pellets with LPS designed to release at a rate of 2.5 or 5.0 μg/kg/d. Food intake and behavior were monitored daily. Rectal temperatures and blood samples were taken on days 0, 1, 2, 3, and 7 post‐implantation. Implantation of the pellets did not induce lethargy and vomiting in the pigs thereby demonstrating the LPS dosages were safe to use in swine. Temperature was increased (P<0.05) by LPS on day 1 but returned to baseline levels by day 2. LPS caused an increase (P<0.05) in neutrophils and a decrease (P<0.05) in lymphocytes indicating the induction of an inflammatory response. Neutrophil and lymphocyte counts returned to baseline levels by day 7. No differences (P>0.05) were observed between the two dosages of LPS. The results of this preliminary study indicate the use of slow‐release LPS pellets are safe and efficacious to use in generating a low‐grade inflammatory response in swine. Supported by: SD Agricultural Experiment Station and the SDSU Research and Support Fund