Objective—To determine effects of repeated aerosol
exposures to fly ash dust on respiratory tracts of tent-confined
Animals—12 weanling Boer-Spanish crossbred
Procedure—Goats were randomly assigned to 2
groups: fly ash treatment group (principal goats,
n = 6) or control group (control goats, 6). Aerosolized fly
ash dust was provided during a 4-hour period for each
of 6 applications given over 3 months and one 2-hour
application prior to necropsy. Fly ash particle diameters
ranged from 0.1 to 130 µm and averaged 17.8 µm, with
1.5% of fly ash particles in the 0.1- to 5-µm-diameter
range. A mean ± SD of 748 ± 152 g/treatment was
delivered inside a tent containing principal goats; control
goats were placed inside a similar tent for 4-hour
treatments without dust. Following treatment, rectal
temperatures were taken at 0, 4, 6, 8, 24, and 72
hours; Hcts were recorded at 0, 24, and 72 hours.
Results—Rectal temperatures were significantly
increased at 4, 6, and 8 hours and decreased at 72
hours, compared with 0 hours. Mean ± SEM Hct values
were significantly increased for principal goats
(37.47 ± 0.39%), compared with control goats (36.17
± 0.42%). A significant increase in the mean area of
gross atelectatic lung lesions (1,410 mm2) was found
in principal goats (n = 6), compared with control goats
(440 mm2; 5).
Conclusions and Clinical Relevance—An increase
in atelectatic lung lesions was observed in principal
goats, compared with control goats; however, overall,
fly ash dust effects were nontoxic. ( Am J Vet Res 2005;66:991–995)
Objective—To compare Salmonella isolates cultured
from feedyard and nonfeedyard (control) playas (ie,
temporary shallow lakes) of the Southern High Plains.
Sample Population—Water and muck (sediment)
samples were obtained from 7 feedyard playas and 3
nonfeedyard playas in the winter and summer.
Procedure—Each water and muck sample was
enriched with sulfur-brilliant-green broth and incubated
in a shaker at 37°C for 24 hours. A sample (100 mL)
of the incubated bacterial-enriched broth was then
mixed with 100 mL of fresh sulfur-brilliant-green
enrichment broth and incubated in a shaker at 37°C
for 24 hours. After the second incubation, a swab
sample was streaked on differential media. Suspect
Salmonella isolates were further identified by use of
biochemical tests, and Salmonella isolates were confirmed
and serovar determinations made.
Results—Salmonella isolates were not recovered
from the 3 control playas. Seven Salmonella enterica
serovars were isolated from 5 of 7 feedyard playas in
the summer, and 13 S enterica serovars were isolated
from 7 of 7 feedyard playas in the winter. In the
summer, 296 isolates were cultured, and 47 were
Salmonella organisms. In the winter, 288 isolates
were cultured, and 171 were Salmonella organisms.
Conclusions and Clinical Relevance—Results indicated
that feedyard playas are frequently contaminated
with many Salmonella serovars. These pathogens
should be considered whenever feedyard managers
contemplate the use of water from these playas.
Water from feedyard playas should not be used to
cool cattle in the summer or for dust abatement. ( Am J Vet Res 2004;65:40–44)
Objective—To investigate the effects of sterile fine dust aerosol inhalation on antibody responses and lung tissue changes induced by Mucor ramosissimus or Trichoderma viride spores following intratracheal inoculation in goats.
Animals—36 weanling Boer-Spanish goats.
Procedures—6 goats were allocated to each of 2 M ramosissimus–inoculated groups, 2 T viride–inoculated groups, and 2 control (tent or pen) groups. One of each pair of sporetreated groups and the tent control group were exposed 7 times to sterilized fine feedyard dust (mean ± SD particle diameter, < 7.72 ± 0.69 μm) for 4 hours in a specially constructed tent. Goats in the 4 fungal treatment groups were inoculated intratracheally 5 times with a fungal spore preparation (30 mL), whereas tent control goats were intratracheally inoculated with physiologic saline (0.9% NaCl) solution (30 mL). Pen control goats were not inoculated or exposed to dust. Goats received an IV challenge with equine RBCs to assess antibody responses to foreign antigens. Postmortem examinations were performed at study completion (day 68) to evaluate lung tissue lesions.
Results—5 of 7 deaths occurred between days 18 and 45 and were attributed to fine dust exposures prior to fungal treatments. Fine dust inhalation induced similar lung lesions and precipitating antibodies among spore-treated goats. Following spore inoculations, dust-exposed goats had significantly more spores per gram of consolidated lung tissue than did their nonexposed counterparts.
Conclusions and Clinical Relevance—Fine dust inhalation appeared to decrease the ability of goats to successfully clear fungal spores from the lungs following intratracheal inoculation.
Objective—To compare the virulence of spores of 7
fungi by tracheal inoculation of goats following exposure
of goats to an aerosol of sterilized feedyard dust.
Animals—54 weanling Boer-Spanish goats.
Procedure—A prospective randomized controlled
study was conducted. There were 7 fungal treatment
groups, a tent control group, and a pen control group
(n = 6 goats/group). Goats in the 7 treatment and tent
control groups were exposed to autoclaved
aerosolized feedyard dust for 4 hours in a specially
constructed tent. Goats in the 7 treatment groups
were then inoculated intratracheally with 30 mL of a
fungal spore preparation, whereas tent control goats
were intratracheally inoculated with 30 mL of physiologic
saline (0.9% NaCl) solution. These treatments
were repeated each week for 6 weeks.
Results—Severity of pathologic changes differed significantly
among the 7 fungal treatment groups as
determined on the basis of gross atelectatic and consolidated
lung lesions and histologic lesions of the
lungs. Descending order for severity of lesions was
Mucor ramosissimus, Trichoderma viride,
Chaetomium globosum, Stachybotrys chartarum,
Aspergillus fumigatus, Penicillium chrysogenum, and
Monotospora lanuginosa. Trichoderma viride spores
were the most invasive and were isolated from the
bronchial lymph nodes and thoracic fluid of all 6 goats
administered this organism. Spores were observedhistologically
in lung tissues harvested 72 hours after
inoculation from all treatment groups.
Conclusions and Clinical Relevance—4 of 7 fungal
spore types induced significantly larger lung lesions,
compared with those induced by the other 3 spore
types or those evident in control goats. (Am J Vet Res 2005;66:615–622)
Objective—To determine the bacterial, fungal, and
endotoxin concentrations in aerosolized ambient air
during the winter and summer in feedyards located in
the Southern High Plains, identify aerosolized microbial
pathogens, and determine the size of microbial
and dust components.
Sample Population—Aerosol samples were
obtained from 7 feedyards.
Procedure—Aerosol samples were collected upwind,
on-site, and downwind from each feedyard at a point
1 m above the ground by use of biological 2- and 6-
stage cascade impactors.
Results—Significantly more microbes were cultured
from on-site and downwind samples than upwind
samples. There were significantly more microbes during
the summer than during the winter. However,
mean endotoxin concentration was significantly higher
during the winter (8.37 ng/m3) than the summer
(2.63 ng/m3). Among 7 feedyards, mean ± SE number
of mesophilic bacteria (1,441 ± 195 colony-forming
units [CFUs]/m3) was significantly higher than mean
number of anaerobic bacteria (751 ± 133 CFUs/m3) or
thermophilic bacteria (54 ± 10 CFUs/m3) in feedyard
air. Feedyard aerosol samples contained more
mesophilic fungi (78 ± 7 CFUs/m3) than thermophilic
fungi (2 ± 0.2 CFUs/m3). Eighteen genera of bacteria
were identified by use of an automated identification
Conclusions and Clinical Relevance—It appeared
that gram-negative enteric pathogens offered little
risk to remote calves or humans via ambient aerosols
and that gram-positive pathogens of the Bacillus,
Corynebacterium, and Staphylococcus spp can be
spread by aerosols in and around feedyards. It was
common to detect concentrations of endotoxin in the
ambient air of 7 feedyards. ( Am J Vet Res 2004;
Objective—To determine the impact of feedyards on
endotoxin concentration, fecal coliform count, and
other water quality measurements during winter and
summer in feedyard playas (shallow lakes).
Sample Population—Water samples obtained from
7 feedyard playas and 3 nonfeedyard control playas.
Procedure—Surface water samples were collected
from each playa and at various depths from 3 feedyard
playas. Endotoxin concentrations, 22 water quality
variables, and fecal coliform counts were determined
in samples collected in summer and winter
from various combinations of playas.
Results—Cattle numbers per feedyard ranged from
40,000 to 175,000 head/y. Mean endotoxin concentrations
were significantly lower in control playas than
in feedyard playas in winter and summer. Endotoxin
concentration appeared to be homogenous at various
water depths. Values for 20 of 22 water quality variables
were higher in the feedyard playas than in control
playas in winter and summer. In winter only, mean
total fecal coliform concentration in feedyard playas
was significantly greater than in control playas.
Conclusions and Clinical Relevance—Results indicated
that feedyards have the potential to impact
water quality in playas, and cattle should not be
allowed access to them. Feedyard playa water should
not be used under high pressure to settle dust in pens
with cattle or to cool cattle, because aerosols containing
pathogens and high concentrations of endotoxin
are a health hazard for humans and cattle. (Am J
Vet Res 2001;62:1402–1407)
Objective—To determine the clinical, clinicopathologic,
and histologic effects of aerosolized feedyard dust
that contains natural endotoxins on adult sheep.
Animals—Eighteen 3-year-old Saint Croix sheep.
Procedure—A prospective randomized controlled
study was conducted. There were 2 treatment groups
(dust-endotoxin group, n = 9; control group, 9).
Aerosolized feedyard dust was provided continuously
during a 4-hour period for each application (once in week
1, 3 times in week 2, and 7 times in week 3) to sheep in
a semiairtight tent. All sheep were euthanatized and
necropsied 8 hours after the treatment group received
the last dust treatment. Variables measured before and
after each dust treatment were rectal temperature,
total WBC count, and concentrations of fibrinogen
Results—Mean amount of dust administered during
each treatment was 451 g/4 h. Filter collection indicated
51 mg of dust/m3 and 7,423 ng of endotoxin.
Mean rectal temperature at 8 hours (40.4 C) and
mean WBC counts 12 and 24 hours after dust treatment
were significantly higher for the treated group
than the means of the respective variables for the
control group. Similar responses were observed with
repeated dust-endotoxin treatments; however, with
each subsequent treatment, there was a diminished
response. Sheep in the treatment group had generalized
alveolar septal thickening and hypercellularity.
Conclusion and Clinical Relevance—Feedyard
dust induced a temporary febrile response and leukocytosis
in sheep in the treatment group. Exposure to
dust that contains endotoxins may be a stressor preceding
acute infectious respiratory tract disease of
marketed sheep. (Am J Vet Res 2002;63:28–35)
Objective—To determine whether increased conglutinin
titers are evident in stressed calves that do not
develop respiratory tract disease in feedlots,compared
with respiratory tract disease, and to determine
the increase in immunoconglutinin titers.
Animals—101 mixed-breed beef calves.
Procedure—Calves were processed at 4 farms of origin
and allowed to remain with their dams for another
100 days. Calves from each farm were brought to a
centrally located order-buyer barn. In a feedlot, 101
calves were assigned to pens and observed daily for
clinical signs of acute respiratory tract disease. When
sick calves were detected, they were treated with
antibiotics and isolated in a pen for 4 days.
Conglutinin and immunoconglutinin titers were determined
for all calves.
Results—During the 28-day study, 73 calves developed
respiratory tract disease, whereas 28 calves
remained healthy. Mean conglutinin titers differed significantly
among calves from the 4 farms. Significant
differences were not detected in conglutinin titers
among calves on the basis of sex, morbidity, or vaccination
status against Mannheimia haemolytica at
each farm, the order-buyer barn, or the feedlot on
days 8, 15, and 28 after arrival. Immunoconglutinin
titers in calves differed significantly among farms and
Conclusions and Clinical Relevance—Mean conglutinin
titers in calves do not appear to be associated with
the incidence of acute respiratory tract disease; however,
increased immunoconglutinin titers appear to be
associated with recovery of stressed calves from respiratory
tract disease during the first 15 days after
arrival in a feedlot. (Am J Vet Res 2000;61:1403–1409)