Objective—To determine whether a monovalent
Leptospira borgpetersenii serovar hardjo (type hardjobovis)
vaccine commercially available in Australia,
New Zealand, Ireland, and the United Kingdom would
protect cattle from renal colonization and urinary
shedding when exposed to a US strain of Leptospira
borgpetersenii serovar hardjo.
Animals—24 Hereford heifers that lacked detectable
antibodies against serovar hardjo.
Procedure—Heifers received 2 doses, 4 weeks
apart, of the commercial hardjo vaccine (n = 8) or a
monovalent US reference hardjo vaccine (8) or were
not vaccinated (controls; 8). Heifers were challenged
16 weeks later by intraperitoneal inoculation or conjunctival
instillation. Serum antibody titers were measured
weekly, and urine samples were examined for
leptospires. Heifers were euthanatized 11 to 14
weeks after challenge, and kidney tissue was examined
for evidence of colonization.
Results—All 8 heifers vaccinated with the reference
vaccine were found to be shedding leptospires in
their urine and had evidence of renal colonization. All
4 control heifers challenged by conjunctival instillation
and 2 of 4 control heifers challenged by intraperitoneal
inoculation shed leptospires in their urine, and
all 8 had evidence of renal colonization. In contrast,
leptospires were not detected in the urine or tissues
of any of the 8 heifers that received the commercial
hardjo vaccine. Heifers that received the commercial
hardjo vaccine had significantly higher antibody titers
than did heifers that received the reference vaccine.
Conclusions and Clinical Relevance—Results suggest
that cattle that received 2 doses of the commercial
hardjo vaccine were protected against renal colonization
and urinary shedding when challenged with L
borgpetersenii serovar hardjo strain 203 four months
after vaccination. (Am J Vet Res 2001;62:995–1000)
Objective—To evaluate antibiotics for treatment of
cattle with leptospirosis caused by Leptospira borgpetersenii
Design—Randomized controlled trial.
Animals—42 healthy mixed-breed cattle.
Procedure—Cattle were inoculated via conjunctival
instillation with L borgpetersenii serovar hardjo. After
infection and urinary shedding of L borgpetersenii
were confirmed, cattle were treated with various
antibiotics. To determine effectiveness of antibiotic
treatment, urinary shedding of L borgpetersenii was
monitored for 4 to 6 weeks after administration of
antibiotics, using darkfield microscopic examination,
microbial culture, immunofluorescence testing, and a
polymerase chain reaction assay.
Results—All inoculated cattle developed leptospirosis
and shed leptospires in their urine. The following
antibiotic treatments resulted in elimination of urinary
shedding of leptospires: a single injection of oxytetracycline
(20 mg/kg [9 mg/lb] of body weight, IM), tilmicosin
(10 mg/kg [4.5 mg/lb], SC), or a combination
product that contained dihydrostreptomycin-penicillin
G (25 mg/kg [11.4 mg/lb], IM) or multiple injections of
ceftiofur sodium (2.2 or 5 mg/kg [1 or 2.3 mg/lb], IM,
once daily for 5 days, or 20 mg/kg, IM, once daily for
Conclusions and Clinical Relevance—Successful
resolution of leptospirosis in cattle by administration
of dihydrostreptomycin-penicillin G confirms results
obtained by other investigators. Three other antibiotics
(oxytetracycline, tilmicosin, and ceftiofur) also
were effective for resolving leptospirosis and may be
useful substitutes for dihydrostreptomycin, an antibiotic
that is no longer available for use in food-producing
animals in the United States. Cost, safety, and
withdrawal times of these various treatment options
need to be considered. (J Am Vet Med Assoc
Objective—To evaluate gross, histopathologic, and
serum biochemical findings caused by Leptospira
interrogans serovars pomona and bratislava inoculated
Animals—Twenty-seven 8-week-old female Beagles.
Procedure—Dogs were randomly assigned to challenge
or control groups. Challenge groups were conjunctivally
inoculated on 3 successive days with
5 ×107L interrogans serovar pomona (n = 12) or
serovar bratislava (11). Clinical signs were recorded
throughout the experiment, and clinical pathology
assays, bacteriologic culture, and necropsies (6 or 7
dogs necropsied at each time point) were done on
postinoculation day (PID) 7, 10, 14, and 20.
Results—Infection could not be confirmed in any
serovar bratislava–inoculated dog, and control dogs
remained healthy throughout the experiment.
Positive culture and fluorescent antibody test results
were confirmed in 11 of 12 serovar pomona–inoculated
dogs. Fever and lethargy starting at PID 7 were
the most common clinical signs in serovar
pomona–infected dogs. On day 10, gross lesions
included multifocal renal and pulmonary hemorrhage
and perirenal edema. Serovar pomona–inoculated
dogs had histopathologic lesions including hepatitis,
interstitial nephritis, and pneumonia at PID 7, 10, 14,
and 20. Increases in BUN, anion gap, and bilirubin
concentration occurred on PID 10, 14, and 20.
Platelet counts in dogs with positive results of bacteriologic
culture were decreased from baseline values
on PID 10, 12, and 14.
Conclusions and Clinical Relevance—
Conjunctival inoculation with L interrogans serovar
pomona resulted in a high rate of infection with concomitant
hemorrhagic and inflammatory lesions of
the kidneys, liver, and lungs. (Am J Vet Res
Objective—To develop a method for inducing acute
leptospirosis in dogs.
Animals—31 nine-week-old female Beagles.
Procedure—Beagles were randomly assigned to 2
inoculation groups or a control group. Dogs were
inoculated on 3 successive days by conjunctival instillation
of 5 X 107 cells of Leptospira kirschneri serovar
grippotyphosa strain 82 (12 dogs) or strain RM 52 (14
dogs). Control dogs (n = 5) were similarly inoculated
with sterile leptospiral culture media. Clinical signs,
clinicopathologic variables, anti-leptospiral antibody
titers, and evidence of leptospires in tissues and body
fluids were evaluated. Dogs were euthanatized and
necropsied on days 7, 14, 22, or 28 after inoculation or
as required because of severe illness.
Results—Clinical signs in infected dogs included conjunctivitis,
lethargy, diarrhea, dehydration, vomiting,
and icterus. Consistent clinicopathologic alterations
included azotemia, hyperphosphatemia, increased
anion gap, hyperbilirubinemia, and an increase in alkaline
phosphatase activity. Leptospires were cultured
from the kidneys (11/12), urine (6/9), aqueous humor
(9/12), blood (12/12), and liver (12/12) of dogs inoculated
with strain 82. Only 3 of 14 dogs became infected
after inoculation with strain RM 52.
Histopathologic lesions in infected dogs included
interstitial nephritis, renal tubular degeneration and
necrosis, pulmonary hemorrhage, and hepatic edema
Conclusions and Clinical Relevance—Conjunctival
exposure to L kirschneri serovar grippotyphosa strain
82 resulted in acute leptospirosis in all inoculated
dogs, but only 3 of 14 dogs inoculated with strain RM
52 became infected. This method of infection by
serovar grippotyphosa can be used to study the
pathogenesis and prevention of leptospirosis in dogs.
(Am J Vet Res 2004;65:1100–1107)
Objective—To determine the distribution of lesions
and extent of tissues infected with Mycobacterium
bovis in a captive population of white-tailed deer.
Animals—116 captive white-tailed deer.
Procedure—Deer were euthanatized, and postmortem
examinations were performed. Tissues with
gross lesions suggestive of tuberculosis were collected
for microscopic analysis and bacteriologic culture.
Tissues from the head, thorax, and abdomen of deer
with no gross lesions were pooled for bacteriologic
culture. Tonsillar, nasal, oral, and rectal swab specimens,
fecal samples, and samples of hay and pelleted
feed, soil around feeding sites, and water from 2 natural
ponds were collected for bacteriologic culture.
Results—Mycobacterium bovis was isolated from 14
of 116 (12%) deer; however, only 9 of 14 had lesions
consistent with tuberculosis. Most commonly affected
tissues included the medial retropharyngeal lymph
node and lung. Five of 14 tuberculous deer had no
gross lesions; however, M bovis was isolated from
pooled tissue specimens from the heads of each of
these deer. Bacteriologic culture of tonsillar swab specimens
from 2 of the infected deer yielded M bovis.
Mean (± SEM) age of tuberculous deer was 2.5 ± 0.3
years (range, 0.5 to 6 years). Mycobacterium bovis was
not isolated from feed, soil, water, or fecal samples.
Conclusions and Clinical Relevance—Examination of
hunter-killed white-tailed deer for tuberculosis commonly
includes only the lymph nodes of the head.
Results of such examinations may underestimate disease
prevalence by as much as 57%. Such discrepancy
should be considered when estimating disease prevalence.
(J Am Vet Med Assoc 2000;216:1921–1924)
Objective—To determine the extent of leptospirosis
in persons exposed to infected swine, confirm the
source of disease, define risk factors for infection,
and identify means for preventing additional infections
during an outbreak in Missouri in 1998.
Sample Population—240 people and 1,700 pigs.
Procedure—An epidemiologic investigation was conducted
of people exposed to infected pigs from the
University of Missouri-Columbia swine herd. The investigation
included review of health of the pigs, a crosssectional
study of the people handling the pigs, serologic
testing of human and porcine sera, and risk-factor
analysis for leptospirosis within the human population.
Results—Serologic testing of samples collected at the
time of the investigation indicated that 59% of the pigs
had titers to leptospires, denoting exposure. Of the
240 people in the exposed study population, 163 (68%)
were interviewed, and of these, 110 (67%) submitted a
blood sample. Nine (8%) cases of leptospirosis were
confirmed by serologic testing. Risk factors associated
with leptospirosis included smoking (odds ratio [OR],
14.4; 95% confidence interval [CI],1.39 to 137.74) and
drinking beverages (OR, 5.1; 95% CI, 1.04 to 24.30)
while working with infected pigs. Washing hands after
work was protective (OR, 0.2; 95% CI, 0.03 to 0.81).
Conclusions and Clinical Relevance—Leptospirosis
is a risk for swine producers and slaughterhouse
workers, and may be prevented through appropriate
hygiene, sanitation, and animal husbandry. It is essential
to educate people working with animals or animal
tissues about measures for reducing the risk of exposure
to zoonotic pathogens. (J Am Vet Med Assoc