Objective—To evaluate various sampling strategies for potential use in measuring prevalence of antimicrobial susceptibility in cattle.
Sample Population—500 isolates of non–type-specific Escherichia coli (NTSEC) isolated from the feces of 50 cows from 2 dairy farms (25 cows/farm and 10 isolates/cow).
Procedures—Diameters of inhibition zones for 12 antimicrobials were analyzed to estimate variation among isolates, cows, and farms and then used to determine sampling distributions for a stochastic simulation model to evaluate 4 sampling strategies. These theoretic sampling strategies used a total of 100 isolates in 4 allocations (1 isolate from 100 cows, 2 isolates from 50 cows, 3 isolates from 33 cows, or 4 isolates from 25 cows).
Results—Analysis of variance composition revealed that 74.2% of variation was attributable to isolates, 18.5% to cows, and 7.3% to farms. Analysis of results of simulations suggested that when most of the variance was attributable to differences among isolates within a cow, culturing 1 isolate from each of 100 cows underestimated overall prevalence, compared with results for culturing more isolates per cow from fewer cows. When variance was not primarily attributable to differences among isolates, all 4 sampling strategies yielded similar results.
Conclusions and Clinical Relevance—It is not always possible to predict the hierarchical level at which clustering will have its greatest impact on observed susceptibility distributions. Results suggested that sampling strategies that use testing of 3 or 4 isolates/cow from a representative sample of all animals better characterize herd prevalence of antimicrobial resistance when impacted by clustering.
Objective—To assess perceptions of personnel working at a veterinary teaching hospital regarding risks of occupational hazards and compare those perceptions with assessments made by occupational safety experts.
Study Population—A representative sample of personnel (n = 90) working at the veterinary teaching hospital at Colorado State University and a panel of 3 occupational safety experts.
Procedures—Hospital personnel ranked perceptions of 14 physical, chemical, and biological workplace hazards and listed the injuries, illnesses, and near misses they had experienced. The expert panel provided consensus rankings of the same 14 hazards for 9 sections of the facility. Risk perceptions provided by the 2 sources were compared.
Results—Risk perceptions did not differ significantly between hospital personnel and the expert panel for most of the site-specific comparisons (94/126 [75%]). Personnel perceived greater risks for some physical hazards (loud noises, sharps injuries, and ionizing radiation) and some chemical or materials exposures (insecticides or pesticides and tissue digester emissions). In contrast, the expert panel perceived greater risks for physical hazards (bite or crush and restraining and moving animals), chemical exposures (anesthetic waste gas), and biological exposures (Toxoplasma gondii, antimicrobial-resistant bacteria, and allergens).
Conclusions and Clinical Relevance—Participants and safety experts had similar perceptions about occupational risks, but there were important differences where hospital personnel apparently overestimated or underappreciated the risks for workplace hazards. This type of study may be useful in guiding development of optimal workplace safety programs for veterinary hospitals.
Objective—To evaluate the potential association between Salmonella enterica shedding in hospitalized horses and the risk of diarrhea among stablemates, and to characterize gastrointestinal-related illness and death following discharge among horses that shed S enterica while hospitalized.
Animals—221 horses (59 that shed S enterica during hospitalization and 162 that tested negative for S enterica shedding ≥ 3 times during hospitalization).
Procedures—Information from medical records (signalment, results of microbial culture of fecal samples, clinical status at the time of culture, and treatment history) was combined with data collected through interviews with horse owners regarding formerly hospitalized horses and their stablemates. Data were analyzed to investigate risk factors for death and diarrhea.
Results—Occurrence of diarrhea among stablemates of formerly hospitalized horses was not associated with S enterica shedding in hospitalized horses but was associated with oral treatment with antimicrobials during hospitalization. Salmonella enterica shedding during hospitalization was not associated with risk of death or gastrointestinal-related illness in study horses ≤ 6 months after discharge, but shedding status and history of gastrointestinal illness were associated with increased risk of death during the preinterview period.
Conclusions and Clinical Relevance—Stablemates of horses that shed S enterica during hospitalization did not appear to have an increased risk for diarrhea, but comingling with horses that receive orally administered antimicrobials may affect this risk. Salmonella enterica shedding during hospitalization may be a marker of increased long-term risk of death after discharge. Risks are likely influenced by the S enterica strain involved and biosecurity procedures used.
Objective—To evaluate the extent of environmental
contamination with Salmonella enterica in a veterinary
Samples—Environmental samples obtained from 69
representative locations within a veterinary teaching
hospital by use of a commercially available electrostatic
Procedure—Environmental samples were obtained for
bacteriologic culture, and antimicrobial susceptibility
testing was performed on each environmental isolate.
Environmental isolates were compared with isolates
obtained from animals during the same period to investigate
potential sources of environmental contamination.
Results—54 S enterica isolates were recovered from
452 (11.9%) cultured environmental samples .Five different
serotypes were recovered; the most common
serotypes were S Newport and S Agona. Within the 5
serotypes recovered, 10 distinguishable phenotypes
were identified by use of serotype and antimicrobial
susceptibility patterns. Of the environmental isolates,
41 of 54 (75.9%) could be matched to phenotypes of
isolates obtained from animal submissions in the
month prior to collection of environmental samples.
Conclusions and Clinical Relevance—Results indicated
that environments in veterinary hospitals can
be frequently contaminated with S enterica near
where infected animals are managed and fecal specimens
containing S enterica are processed for culture
in a diagnostic laboratory. Bacteriologic culture of
environmental samples collected with electrostatic
wipes is an effective means of detecting contamination
in a veterinary hospital environment and may be
beneficial as part of surveillance activities for other
veterinary and animal-rearing facilities. (J Am Vet Med Assoc 2004;225:1344–1348)
Objective—To characterize biosecurity and infection control practices at veterinary teaching hospitals located at institutions accredited by the AVMA.
Population—50 biosecurity experts at 38 veterinary teaching hospitals.
Procedures—Telephone interviews were conducted between July 2006 and July 2007, and questions were asked regarding policies for hygiene, surveillance, patient contact, education, and awareness. Respondents were also asked their opinion regarding the rigor of their programs.
Results—31 of 38 (82%) hospitals reported outbreaks of nosocomial infection during the 5 years prior to the interview, 17 (45%) reported > 1 outbreak, 22 (58%) had restricted patient admissions to aid mitigation, and 12 (32%) had completely closed sections of the facility to control disease spread. Nineteen (50%) hospitals reported that zoonotic infections had occurred during the 2 years prior to the interview. Only 16 (42%) hospitals required personnel to complete a biosecurity training program, but 20 of the 50 (40%) respondents indicated that they believed their hospitals ranked among the top 10% in regard to rigor of infection control efforts.
Conclusions and Clinical Relevance—Results suggested that differences existed among infection control programs at these institutions. Perceptions of experts regarding program rigor appeared to be skewed, possibly because of a lack of published data characterizing programs at other institutions. Results may provide a stimulus for hospital administrators to better optimize biosecurity and infection control programs at their hospitals and thereby optimize patient care.
Objective—To evaluate the efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage (EIPH) in Thoroughbred racehorses under typical racing conditions.
Design—Randomized, placebo-controlled, blinded, crossover field trial.
Animals—167 Thoroughbred racehorses.
Procedures—Horses were allocated to race fields of 9 to 16 horses each and raced twice, 1 week apart, with each of the 2 races consisting of the same race field and distance. Each horse received furosemide (500 mg, IV) before one race and a placebo (saline solution) before the other, with the order of treatments randomly determined. Severity of EIPH was scored on a scale from 0 to 4 after each race by means of tracheobronchoscopy. Data were analyzed by means of various methods of multivariable logistic regression.
Results—Horses were substantially more likely to develop EIPH (severity score ≥ 1; odds ratio, 3.3 to 4.4) or moderate to severe EIPH (severity score ≥ 2; odds ratio, 6.9 to 11.0) following administration of saline solution than following administration of furosemide. In addition, 81 of the 120 (67.5%) horses that had EIPH after administration of saline solution had a reduction in EIPH severity score of at least 1 when treated with furosemide.
Conclusions and Clinical Relevance—Results indicated that prerace administration of furosemide decreased the incidence and severity of EIPH in Thoroughbreds racing under typical conditions in South Africa.
Objective—To evaluate trends in feedlot cattle mortality
ratios over time, by primary body system affected,
and by type of animal.
Design—Retrospective cohort study.
Animals—Approximately 21.8 million cattle entering
121 feedlots in the United States during 1994 through
Procedures—Yearly and monthly mortality ratios
were calculated. Numbers of deaths were modeled
by use of Poisson regression methods for repeated
measures. Relative risks of death over time and by
animal type were estimated.
Results—Averaged over time, the mortality ratio
was 12.6 deaths/1,000 cattle entering the feedlots.
The mortality ratio increased from 10.3
deaths/1,000 cattle in 1994 to 14.2 deaths/1,000
cattle in 1999, but this difference was not statistically
significant (P = 0.09). Cattle entering the feedlots
during 1999 had a significantly increased risk
(relative risk, 1.46) of dying of respiratory tract disorders,
compared with cattle that entered during
1994, and respiratory tract disorders accounted for
57.1% of all deaths. Dairy cattle had a significantly
increased risk of death of any cause, compared with
beef steers. Beef heifers had a significantly
increased risk of dying of respiratory tract disorders,
compared with beef steers.
Conclusions and Clinical Relevance—Results suggested
that although overall yearly mortality ratio did
not significantly increase during the study, the risk of
death attributable to respiratory tract disorders was
increased during most years, compared with risk of
death during 1994. The increased rates of fatal respiratory
tract disorders may also reflect increased rates
of non-fatal respiratory tract disorders, which would
be expected to have adverse production effects in
surviving animals. (J Am Vet Med Assoc 2001;219:1122–1127)
Objective—To describe time-dependent changes in
plasma concentrations of 3-methylindole (3MI) and
blood concentrations of 3-methyleneindolenine
(3MEIN)-adduct in feedlot cattle.
Animals—64 yearling steers.
Procedures—Steers were assigned to 2 groups (32
steers/group). During the first 8 weeks, blood samples
were collected from group 1 before the morning
ration was fed, whereas samples from group 2 were
collected 2 to 3 hours after the ration was fed. Blood
samples were collected from all steers approximately
4 times/wk for 3 weeks and 3 times/wk for the subsequent
5 weeks. Samples were collected at the
same time for all steers for an additional 10 weeks.
Plasma samples were analyzed for 3MI concentrations.
Blood samples collected from cattle in group 2
during the first 8 weeks were analyzed for 3MEINadduct
Results—Mean blood concentration of 3MEINadduct
increased to a maximum value on day 33 (0.80
U/μg of protein) and then decreased to a minimum on
day 54 0.40 U/μg of protein). Plasma 3MI concentrations
initially decreased and remained low until after
day 54. Group-1 cattle had lower plasma 3MI concentrations,
compared with concentrations for group-2
cattle. Blood 3MEIN-adduct concentrations and plasma
3MI concentrations were not associated with
deleterious effects on weight gains.
Conclusions and Clinical Relevance—Blood
3MEIN-adduct concentrations peaked during the period
of greatest risk for development of bovine respiratory
disease complex. Conversely, plasma 3MI concentrations
decreased during the same period.
Animal-to-animal variation in metabolic capacity to
convert 3MI to 3MEIN may be of more importance
than differences in plasma 3MI concentration. Am J Vet Res (2002;63:591–597).
Objective—To evaluate efficacy of 2 disinfectants as
used in footbaths in veterinary hospitals for reducing
bacterial contamination of footwear.
Sample Population—Bacteria collected from the
soles of rubber boots after experimental contamination
and exposure to disinfectant solutions or control
Procedures—Investigators contaminated boots by
walking through soiled straw animal bedding. Swab
samples were collected from the sole of 1 boot (right
or left) without treatment. The other boot was briefly
immersed in a disinfectant solution (either a quaternary
ammonium compound [QAC] or a peroxygen
compound) or water, and samples were collected
after 7 minutes. Differences associated with the
experimental treatments were analyzed statistically.
Veterinary teaching hospitals (VTHs) in the United
States and Canada were contacted to obtain information
about the use of footbaths.
Results—Mean bacterial concentrations from peroxygen-treated boots were 67% to 78% lower, compared
with samples taken from untreated boots. In
contrast, there were no statistically detectable differences
in mean bacterial concentrations in samples
taken from QAC- or water-treated boots, compared
with control boots. Disinfectant footbaths were
reportedly used in 30 of 31 VTHs.
Conclusions and Clinical Relevance—Disinfectant
solution containing peroxygen applied in a footbath
reduced bacterial concentrations on rubber boots
under conditions representative of those found in
VTHs. Footbaths are commonly used as a method to
control infectious diseases in veterinary hospitals.
Disinfectant footbaths should not be expected to sterilize
footwear, but they may help in reducing the risk for
nosocomial infection when used with effective disinfectants.
(J Am Vet Med Assoc 2005;226:2053–2058)
Objective—To assess the likelihood of an introduction of foot-and-mouth disease (FMD) into the Malaysia-Thailand-Myanmar (MTM) peninsula through terrestrial movement of livestock.
Animals—89,294 cattle and buffalo legally moved into the MTM peninsula.
Procedures—A quantitative risk assessment was conducted by use of a stochastic simulation. Patterns of livestock movement were ascertained through review of relevant governmental records and regulations and by interviewing farmers, traders, and local officers when the records did not exist. Parameters identified in the process were the probabilities of livestock having FMD and of FMD infection going undetected during import processes. The probability of an animal accepted for import having FMD was also assessed. Sensitivity analysis was performed to determine the effects that each parameter had on the model.
Results—The simulation yielded an average consignment prevalence of 10.95%. Typically, each animal in a quarantine facility had a 2.7% chance of having an inapparent form of FMD infection; hence, it was likely an animal would not be identified as infected. Findings revealed that the mean probability of an animal accepted for import having FMD was 2.9%, and the risk was as high as 11%.
Conclusions and Clinical Relevance—Results of the model allowed for the evaluation of movement regulations currently imposed in the MTM peninsula. Evidence from the study suggested that current practices in animal movement were far from efficient in preventing introduction of FMD-infected animals into the MTM region, and additional measures will be necessary.