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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #131369
Title: EFFECTS OF AEROSOLIZED DUST IN GOATS ON LUNG CLEARANCE OF PASTEURELLA AND MANNHEIMIA SPECIES

Author
item Purdy, Charles
item STRAUS, DAVID - TEXAS TECH UNIVERSITY
item CHIRASE, N - TAES - AMARILLO, TX
item AYERS, JON - TAMU VET. DIAG. LAB.
item HOOVER, MARK - LOVELACE RESP. RES. INST.

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2002
Publication Date: 3/24/2003
Citation: Purdy, C. W., Straus, D. C., Chirase, N., Ayers, J. R., Hoover, M. D. Effects of aerosolized dust in goats on lung clearance of Pasteurella and Mannheimia species. Current Microbiology. 2003. v. 45. p. 174-179.

Interpretive Summary: Feedyard dust is considered to have a negative health effect on ruminants confined to feedyards in the Southern High Plains. Aerosol experimentation using feedyard dust have not been conducted. Conventional wisdom states that dust laden ruminant lung macrophages (particle/bacterial eating cells) are less efficient when exposed to pneumonic bacterial pathogens. This would imply that goats subjected to a dusty environment, especially dust particles under 5 microns (which are inspired deep into the lung) would be more susceptible to pneumonic bacteria. Two of the most important bacterial pathogens that induce pneumonia in ruminants are Pasteurella multocida and Mannheimia haemolytica. Twenty-four weanling goats were randomly allotted to 4 treatment groups, 6 goats per group. Two control groups (C1 & C2) did not receive any dust, and 2 principal groups (P1 and P2) received a total of 14 four-hour dust treatments except for the last dusting which was 1-1/2 2hr long. Immediately after the 10 dust treatments on day 12 of the experiment, P1 and P2 and C1 and C2 goats were similarly injected into the right posterior lobe of the lung. The objective was to determine if the inhalation of large quantities of dust predisposed the animals to lung bacterial proliferation. All 24 goats were necropsied on the 4th day following the bacterial injection into the lung and their lungs were examined for gross and histopathological lesions. Results showed that the dusted goats developed a fever and increase in white blood cells after the first dust treatment. Dusted animals demonstrated lung clearance of two potential bacterial pathogens that was not significantly different from that shown by non-dusted controls. Under these conditions, dust may not be as negative an impact on health as previously thought.

Technical Abstract: Twenty-four weanling female Spanish goats were randomly allotted to four treatment groups (n=6/group). Two control groups (C1 and C2) did not receive dust treatments and two principal groups (P1 and P2) received a total of 14 dust treatments each. The dust treatments were each 4 hr, except for the last one which was shortened to 1 « hr. The C1 and P1 group of goats each received a transthoracic challenge of live Mannheimia haemolytica (4x10**6 colony forming units CFU). The C2 and P2 group of goats each received a transthoracic challenge of live Pasteurella multocida (1.0x10**6 CFU/goat). The transthoracic bacterial challenge was administered in 1 ml of phosphate buffered saline (PBS) in the posterior lobe of the right lung of each goat immediately after the 10th dust treatment on day 12 of the study for P1 and P2 groups, and the C1 and C2 goats were similarly injected on the same day. The objective was to determine if the inhalation of large quantities of feedyard dust predisposed the animals to pulmonary bacterial proliferation. All 24 animals were sacrificed on the fourth day following the transthoracic bacterial challenge. Serum and white blood cells (WBC) were obtained from the animals on days -5, +5, +7, +11, and +15. The results showed that dusted animals had fever when compared to non-dusted controls. In addition, dusted animals demonstrated a leukocytosis with neutrophilia, after the first dust treatment which was not sustainable. Dusted and nondusted animals did not differ in their hemagglutination responses to IV injected equine red blood cells. Finally, dusted animals demonstrated pulmonary clearance of two potential bacterial pathogens that was not significantly different from that shown by control (not dusted) animals.