Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2006
Publication Date: 7/1/2007
Citation: Purdy, C.W., Straus, D.C., Hoover, M.D. 2007. Fever and leukocytosis responses in goats to inhaled endotoxin are dose-dependent. ScienceDirect. Small Ruminant Research. 70:140-144.
Interpretive Summary: Endotoxin is found in the cell membrane of all Gram-negative bacteria and these bacteria are very numerous in manure which dries eventually and becomes dust. The endotoxin dose response of ruminants including goats is poorly understood. The question we asked in this study, if the threshold dose of endotoxin/dust was increased, would it induce a greater increase in the fever and white blood cell counts (WBC). This question was examined by keeping the endotoxin/dust dose constant over time and changing the time that goats were exposed. It was found that a 4 hr exposure of endotoxin/dust in goats gave a more rapid and longer period of fever compared to a 3 hr exposure and both the 1 hr and 15 min exposure were similar to the no dust control response. The WBC were increased for both the 4hr and 1hr group at 8 hr post endotoxin/dust treatment, but the 4 hr group had a maximum increase at 12 hr. The 4 hr group samples were lost during 8 to 24 hrs and the 15 min group was not significantly different than the control group during the 8 to 12 hr period of time. It was concluded that if the threshold dose of endotoxin/dust was exceeded it would increase the fever and WBC. The WBC appears to be a more sensitive indicator that the fever response. This finding is important to the scientist to better understand the endotoxin/dust dose response in ruminants, and if endotoxin has an effect on animal production.
Technical Abstract: Forty-five, weanling goats were randomly allotted to five treatment groups: one control group (no dust) and four principal groups (organic dust for 15 min, 1 hr, 3hr, and 4 hr). Inhalation exposures were performed in a closed tent. The amount of endotoxin calculated to be in the dust was shown to be 26.9 µg/g. The amounts of dust introduced into the tent were 4.58 g/m3 of air (15 minutes); 7.46 g/m3 of air (1 hr); 14.82 g/m3 of air (3 hr); and 40.60 g/m3 of air (4 hr). There was a significant increase in the white blood cell counts in the animals dusted for 4h, at 8 hr and 12 hr following exposure. There was a significant decrease in the lymphocyte cell count following the 15 min exposure at 12 hr post exposure, and there was a significant increase in the lymphocyte cell count following the 4 hr exposure, 24 hr after the exposure. There was a significant increase in the neutrophil cell count 8 hr and 12 hr following the 4 hour exposure, while there was a significant decrease in the neutrophil cell count 48 hr following the 4 hr exposure. There was a significant increase in the rectal temperatures of all goats receiving the 4 hour dust exposure at all time periods tested. There was a significant increase in the rectal temperatures of goats following the 1 hr exposure, 8 hours later. These results indicate that the larger the dose of inhaled endotoxin, the higher the resultant fever and leukocytosis.