Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/8/1999
Publication Date: N/A
Technical Abstract: Eighteen 3 yr-old sheep were randomized into two treatment groups (Dust n=9 and Control n=9). Dust in a semi-air tight tent was constant over a 4-hr period for each application. Design: The dust group was given dust one day in week one, three days in week two, seven days in week three, and four days in week four. The non-dust group was placed in a non-dust tent on the esame days and time periods as the dust group. All sheep were necropsied eight hours after the dust group received their last dust episode. These variables were followed at the start and end of each dust event: pre-rectal body temperature and total CBC counts. They were also taken after the dust event(s) at 4 hr, 8 hr, 12 hr, and 20 hr. The average amount of dust given on each dust episode was 451 g in 4-hr. Millipore filter collection indicated 51 mg dust/m**3/30 min or 7423 ng ET/m**3/30 min. Five-stage cyclone impactor determined the mean amount and size of fine dust particles sfor a 4-hr dust period. The particle size and weight of dust in each stag was as follows: dust collected on filter (< 0.32 m) - 0.0089 g, stage-5 (0.32 m) - 0.0524 g, stage-4 (0.65 m) - 0.0411 g, stage-3 (1.4m) - 0.1428 g, stage-2 (2.1 m) - 0.0833 g, and stage-1 (5.4 m) 0.2112 g. The average air flow rate for the cyclone vacuum pump was 29.3 L/min over the 4-hr dust event. The endotoxin (146 g ET/g of dust) induced in the sheep a significant mean maximum body temperature (40 deg C) in 8 hr and a maximum total WBC count (12,219 /mm**3) in 20 hr after the dust event. The differences in these two variables became less apparent after several dust events. Three to five percent of inhaled dust reached alveoli. There were no gross lung lesions due to dust.