Objective—To use real-time polymerase chain reaction
(PCR) technology to develop a highly sensitive
and specific diagnostic assay for the detection of
Salmonella spp in fecal specimens.
Sample Population—299 fecal specimens from cattle,
horses, and dogs.
Procedure—Enrichment of fecal specimens was followed
by genomic DNA extraction by use of commercially
available isolation kits. Real-time PCR assay
was performed to target a Salmonella spp-specific
DNA segment. Results of real-time PCR assay were
compared with bacterial culture results to determine
relative sensitivity and specificity.
Results—Use of the spaQ primer-probe set resulted
in a relative sensitivity of 100% and a specificity of
98.2%, compared with bacterial culture results when
tested on 299 clinical fecal specimens.
Conclusion and Clinical Relevance—A rapid, sensitive,
and specific assay for the detection of
Salmonella spp from enriched clinical fecal specimens
was developed. This technique would be highly valuable
in clinical settings to help avoid or mitigate the
complications arising from an outbreak of salmonellosis
in a herd or among patients of a veterinary hospital.
(Am J Vet Res 2002;63:1265–1268)
Objective—To evaluate antimicrobial susceptibility of commensal Escherichia coli strains isolated from the feces of horses and investigate relationships with hospitalization and antimicrobial drug (AMD) administration.
Animals—68 hospitalized horses that had been treated with AMDs for at least 3 days (HOSP–AMD group), 63 hospitalized horses that had not received AMDs for at least 4 days (HOSP–NOAMD group), and 85 healthy horses that had not been hospitalized or treated with AMDs (community group).
Procedures—Fecal samples were submitted for bacterial culture, and up to 3 E coli colonies were recovered from each sample. Antimicrobial susceptibility of 724 isolates was evaluated. Prevalence of resistance was compared among groups by use of log-linear modeling.
Results—For 12 of the 15 AMDs evaluated, prevalence of antimicrobial resistance differed significantly among groups, with prevalence being highest among isolates from the HOSP–AMD group and lowest among isolates from the community group. Isolates recovered from the HOSP–AMD and HOSP–NOAMD groups were also significantly more likely to be resistant to multiple AMDs. Resistance to sulfamethoxazole and resistance to trimethoprim-sulfamethoxazole were most common, followed by resistance to gentamicin and resistance to tetracycline. Use of a potentiated sulfonamide, aminoglycosides, cephalosporins, or metronidazole was positively associated with resistance to 1 or more AMDs, but use of penicillins was not associated with increased risk of resistance to AMDs.
Conclusion and Clinical Relevance—Results suggest that both hospitalization and AMD administration were associated with prevalence of antimicrobial resistance among E coli strains isolated from the feces of horses.
Objective—To identify factors associated with development of vesicular stomatitis (VS).
Sample Population—138 livestock premises and 118 horses suspected of having VS in Texas, New Mexico, and Colorado.
Procedures—Premises with ≥ 1 animal with clinical signs and laboratory confirmation of infection were classified as case premises. Premises where laboratory confirmation results were negative were control premises. Among equine premises, case and control horses were selected on the basis of premises status. A survey was conducted to identify factors associated with VS for premises and specific horses.
Results—Control of insect populations in the 2 weeks before the VS investigation decreased the odds of disease for premises where vegetation coverage was grassland or pasture (odds ratio [OR], 0.08; 95% confidence interval [CI], 0.01 to 0.7). Odds of VS for premises covered with grassland or pasture increased when measures to control insect populations were not used (OR, 11; 95% CI, 0.8 to 156.3) and for premises that had a body of water (OR, 2.3; 95% CI, 1.0 to 5.6). Use of measures to prevent insect bites or harassment by insects (OR, 0.2; 95% CI, 0.1 to 0.8) and spending time in shelters (OR, 0.4; 95% CI, 0.2 to 1.1) in the 2 weeks prior to investigation decreased the odds of being a case horse.
Conclusions and Clinical Relevance—Insect control and spending time in shelters decreased the odds for infection with VS. Premises covered with grassland or pasture or that had a body of water were at a higher risk.
Objective—To evaluate the prevalence of nasal colonization
with methicillin-resistant Staphylococcus
aureus (MRSA) in horses and horse personnel.
Design—Prospective prevalence study.
Sample Population—972 horses and 107 personnel
from equine farms in Ontario, Canada and New York
Procedure—Nasal swab specimens were collected
from horses and humans on farms with (targeted surveillance)
and without (nontargeted surveillance) a history
of MRSA colonization or infection in horses during
the preceding year. Selective culture for MRSA was
performed. Isolates were typed via pulsed-field gel
electrophoresis, and antibiograms were determined.
Results—MRSA was isolated from 46 of 972 (4.7%)
horses (0/581 via nontargeted surveillance and
46/391 [12%] via targeted surveillance). Similarly,
MRSA was isolated from 14 of 107 (13%) humans
(2/41 [5%] from nontargeted surveillance and 12/66
[18%] from targeted surveillance). All isolates were
subtypes of Canadian epidemic MRSA-5, an uncommon
strain in humans. All isolates were resistant to at
least 1 antimicrobial class in addition to β-lactams. On
all farms with colonized horses, at least 1 human was
colonized with an indistinguishable subtype. For horses,
residing on a farm that housed > 20 horses was
the only factor significantly associated with MRSA
colonization. For humans, regular contact with > 20
horses was the only identified risk factor.
Conclusions and Clinical Relevance—Results confirm
a reservoir of colonized horses on a variety of farms in
Ontario and New York and provide evidence that 1
MRSA strain is predominantly involved in MRSA colonization
in horses and humans that work with horses.
(J Am Vet Med Assoc 2005;226:580–583)
Objective—To estimate prevalence of fecal shedding
of Salmonella spp among horses in the US horse population
and prevalence of Salmonella spp in grain or
other concentrate used as horse feed on equine operations
in the United States.
Sample Population—Horses on 972 operations in 28
Procedure—Fecal samples were collected from horses
resident at each operation. Only a single sample
was collected from any individual horse; number of
horses from which samples were collected on each
operation was determined on the basis of number of
horses on the operation. A single sample of grain or
concentrate was also collected from each operation.
All samples were tested for Salmonella spp by means
of bacterial culture.
Results—Overall, 0.8% (SE, 0.5) of resident horses
shed Salmonella spp in their feces. The overall prevalence
of operations positive for fecal shedding of
Salmonella spp (ie, operations with ≥ 1 horse shedding
Salmonella spp in its feces) was 1.8% (SE, 0.7).
Prevalence of grain or other concentrate samples positive
for Salmonella spp was 0.4%. Serotypes of
Salmonella spp that were identified in grain or other
concentrate were not those typically associated with
clinical disease in horses.
Conclusions and Clinical Relevance—Results suggest
that the national prevalence of fecal shedding of
Salmonella spp by horses in the United States was
0.8%, and that prevalence of Salmonella spp in grain
or other concentrate used for horse feed was 0.4%.(J
Am Vet Med Assoc 2000;217:226–230)
Objective—To evaluate factors potentially associated
with fecal Salmonella shedding among equine
patients hospitalized for colic at a veterinary teaching
hospital and to determine the effects of probiotic
treatment on fecal Salmonella shedding and clinical
Design—Longitudinal study and controlled trial.
Animals—246 equine colic patients.
Procedure—History and medical information were
obtained from patient records. Fecal and environmental
samples were submitted for aerobic bacterial culture
for Salmonella enterica. Fifty-one patients were
treated with a commercially available probiotic; 46
were treated with a placebo. Logistic regression was
used to evaluate data.
Results—Salmonella organisms were detected in
feces from 23 (9%) patients at least once during hospitalization.
Patients were more likely to shed
Salmonella organisms if diarrhea was evident ≤ 6
hours after hospitalization and duration of hospitalization
exceeded 8 days (odds ratio [OR], 20.3), laminitis
developed during hospitalization (OR, 12.0), results of
nasogastric intubation were abnormal (OR, 4.9),
leukopenia was evident ≤ 6 hours after hospitalization
(OR, 4.6), or travel time to the teaching hospital
exceeded 1 hour (OR, 3.5). Horses treated with the
probiotic did not differ from control horses in regard to
likelihood of fecal Salmonella shedding (OR, 1.5) or
prevalence of clinical signs.
Conclusions and Clinical Relevance—Results suggest
that certain risk factors are associated with fecal
shedding of S enterica among equine patients hospitalized
at a veterinary teaching hospital because of
colic and that pathogen monitoring in patients and the
hospital environment and use of barrier nursing precautions
for equine colic patients are beneficial. (J Am
Vet Med Assoc 2001;218:740–748)
Objective—To determine current practices regarding
use of antimicrobials in equine patients undergoing
surgery because of colic at veterinary teaching hospitals.
Sample Population—Diplomates of the American
College of Veterinary Surgeons performing equine
surgery at veterinary teaching hospitals in the United
Procedure—A Web-based questionnaire was developed,
and 85 surgeons were asked to participate. The
first part of the survey requested demographic information
and information about total number of colic
surgeries performed at the hospital, number of colic
surgeries performed by the respondent, and whether
the hospital had written guidelines for antimicrobial
drug use. The second part pertained to nosocomial
infections. The third part provided several case scenarios
and asked respondents whether they would
use antimicrobial drugs in these instances.
Results—Thirty-four (40%) surgeons responded to
the questionnaire. Respondents indicated that most
equine patients undergoing surgery because of colic
at veterinary teaching hospitals in the United States
received antimicrobial drugs. Drugs that were used
were similar for the various hospitals that were represented,
and for the most part, the drugs that were
used were fairly uniform irrespective of the type of
colic, whereas the duration of treatment varied with
the type of colic and the surgical findings. The combination
of potassium penicillin and gentamicin was the
most commonly used treatment.
Conclusions and Clinical Relevance—Results of
this study document the implementation of recommendations
by several authors in veterinary texts that
antimicrobial drugs be administered perioperatively in
equine patients with colic that are undergoing surgery.
However, the need for long-term antimicrobial drug
treatment in equine patients with colic is unknown. (J
Am Vet Med Assoc 2002;220:1359–1365)
Objective—To develop a questionnaire for self-assessment of biosecurity practices at equine boarding facilities and to evaluate infectious disease control practices in these facilities in Colorado.
Sample Population—64 equine boarding facilities in Colorado.
Procedures—Survey questions were rated according to importance for prevention and containment of equine infectious diseases. Point values (range, 0 to 20) were assigned for possible responses, with greater values given for optimal infection control methods. Questionnaires were mailed to equine boarding facilities in Colorado advertised on the World Wide Web. Survey responses were compared with assessments made by a member of the research team during visits to 30 randomly selected facilities. Agreement among results was analyzed via a kappa test and rated as poor, fair, moderate, substantial, or nearly perfect.
Results—Survey responses were received for 64 of 163 (39%) equine boarding facilities. Scores ranged from 106 to 402 points (maximum possible score, 418). Most facilities received better scores for movement and housing of equids than for other sections of the survey. Respondents at 24 of 48 (50%) facilities that routinely received new equids reported isolation of new arrivals. Agreement between self-assessment by survey respondents and evaluation by a member of the research team was determined to be fair to substantial.
Conclusions and Clinical Relevance—Most equine boarding facilities have opportunities to improve measures for prevention or containment of contagious diseases (eg, isolation of newly arrived equids and use of written health management protocols). Most self-assessments of infection control practices were accurate.
Objective—To identify factors associated with excessive
proportions of early fetal losses associated with
mare reproductive loss syndrome in central Kentucky
Procedure—Questionnaires were used to collect
information on farm-, pasture-, and individual animallevel
factors purportedly associated with mare reproductive
loss syndrome. Data were collected for 133
farms (97 with excessive proportions of early fetal
losses and 36 control farms) representing 6,576
Results—Factors significantly associated with an
increased risk of excessive early fetal losses were
exposure to moderate to high concentrations of
Eastern tent caterpillars, exposure to cherry trees,
farm size ≥ 50 broodmares, being bred during
February 2001, and frequent exposure to waterfowl.
Feeding hay to mares outside was associated with a
decreased risk of excessive proportions of early fetal
losses. Pasture composition and management factors
were not significantly different between affected
and control pastures. Individual animal-level factors
were investigated on 6 farms representing 340
mares, and age, parity, and pre- and postbreeding
treatments were not significantly associated with risk
of early fetal loss.
Conclusions and Clinical Relevance—Results suggest
that limiting exposure to Eastern tent caterpillars
and cherry trees and feeding hay to mares outside
may help decrease the risk of excessive proportions
of early fetal losses associated with mare reproductive
loss syndrome. (J Am Vet Med Assoc 2003;222:
Objective—To determine historical, physical examination,
clinicopathologic, and postmortem findings in
horses with putative uremic encephalopathy.
Animals—5 horses with renal failure and neurologic
disease not attributable to abnormalities in any other
Procedure—Medical records from 1978 to 1998 were
examined for horses with renal disease and neurologic
signs not attributable to primary neurologic, hepatic,
or other diseases. Signalment, history, physical
examination findings, clinicopathologic data, renal
ultrasonographic findings, and postmortem data were
Results—Of 332 horses with renal disease, 5 met
selection criteria. Historical findings, physical examination
findings, clinicopathologic data, ultrasonographic
data, and postmortem findings were consistent
with chronic renal failure. Swollen astrocytes
were detected in all 4 horses examined at necropsy.
Conclusions and Clinical Relevance—A single criterion
was not determined to be pathognomonic for
uremic encephalopathy in horses. Uremic encephalopathy
should be considered as a differential diagnosis
in horses with evidence of chronic renal failure
and encephalopathic neurologic sign not attributable
to other causes. Astrocyte swelling, which was common
to all 4 horses examined at necropsy, may
serve as a microscopic indicator of uremic
encephalopathy in horses. (J Am Vet Med Assoc