Objective—To evaluate serum titers obtained by use
of the microscopic agglutination test (ie, MAT titers)
to Leptospira interrogans serovar pomona and autumnalis
and Leptospira kirschneri serovar grippotyphosa
in dogs given a commercial vaccine against serovars
pomona and grippotyphosa.
Animals—Forty 12-week-old puppies and 20 mature
Procedure—Puppies received a commercial vaccine
against serovars pomona and grippotyphosa at 12 weeks
of age, then received a booster vaccine and 3 weeks
later; mature dogs received the vaccine once. Serum
MAT titers to serovars pomona, autumnalis, and grippotyphosa
were measured before vaccination and at 2, 4, 6,
10, and 16 weeks after the first or only vaccination.
Results—Of the 40 puppies vaccinated, 40, 0, and 40
developed MAT titers of > 100 after vaccination to
serovars pomona, grippotyphosa, and autumnalis,
respectively. Microscopic agglutination test titers to
serovar autumnalis were higher than MAT titers to
serovars pomona and grippotyphosa and persisted in
some dogs for 16 weeks (6 weeks longer than for
titers to serovar pomona). Of the 20 mature dogs, 13,
5, and 20 developed MAT titers of > 100 at 2 weeks
to serovars pomona, grippotyphosa, and autumnalis,
respectively. Titers to serovar pomona were higher
and persisted in some dogs beyond 16 weeks after
vaccination, compared with titers to serovars pomona
and grippotyphosa, which persisted for 10 and 6
Conclusions and Clinical Relevance—Subunit vaccines
against serovars pomona and grippotyphosa
induce MAT titers not only to homologous antigens
but also to serovar autumnalis, which could lead to a
misdiagnosis of leptospirosis caused by serovar
autumnalis. (Am J Vet Res 2005;66:1780–1784)
Objective—To estimate the prevalence of fecal shedding of Salmonella spp among bovine patients at a veterinary teaching hospital, to identify risk factors for fecal shedding of Salmonella organisms, and to characterize the serotypes.
Design—Retrospective cohort study.
Sample Population—5,398 hospitalized cattle.
Procedures—Data were collected for all cattle admitted during an 11-year period. Fecal shedding of Salmonella spp was determined by means of standard bacteriologic culture. Multivariable logistic regression models were used to identify risk factors for shedding of Salmonella spp among patients.
Results—The prevalence of Salmonella shedding among clinical suspects was 6.5% (50/768), whereas that among nonsuspects tested through routine surveillance was 2.5% (50/2,020). Among clinical suspect calves, fecal shedding of Salmonella spp was more likely for those admitted in the fall (odds ratio [OR], 5.9), those with septicemia (OR, 3.3), or those with an umbilical hernia (OR, 8.6). Among clinical suspect adult cattle, those with enteritis (OR, 9.9) or metritis (OR, 5.2) were more likely to be shedding Salmonella spp. Among nonsuspect cattle, none of the variables were significant predictors of shedding status. Twenty-one serotypes were detected during the study period, with the most common being Salmonella enterica serotypes Typhimurium (33%), Newport (23%), and Agona (12%).
Conclusions and Clinical Relevance—Seasonal and disease risk factors for fecal shedding of Salmonella spp were evident among clinical suspect cattle admitted to a veterinary teaching hospital. In contrast, lack of significant associations among nonsuspect cattle would suggest that targeted screening within this population is not warranted.
Objective—To elucidate the ecology of Listeria monocytogenes on dairy cattle farms by determining the prevalence of the organism in various samples.
Sample Population—Dairy cattle operations in central New York State.
Procedures—A repeated cross-sectional study design was used. Various samples were obtained from cattle (feces, composite udder milk, and udders), their environment (silage, feed bunks, water troughs, and floor bedding), inline milk filters, and bulk tank milk from 50 dairy farms. Samples were tested for L monocytogenes by use of a PCR assay with 2 steps of bacterial enrichment. Data were analyzed with mixed-effect logistic regression to control for the potential clustering of L monocytogenes on particular farms.
Results—L monocytogenes was detected in composite milk, udder swab samples, and fecal samples at prevalences of 13%, 19%, and 43%, respectively. There was no significant clustering of the pathogen by farm. Listeria monocytogenes was more common in samples obtained from cattle and the environment during winter and summer versus the fall. The prevalence of L monocytogenes was twice as high in samples obtained from feed bunks, water troughs, and bedding, compared with that in samples obtained from silage (65%, 66%, 55%, and 30%, respectively).
Conclusions and Clinical Relevance—L monocytogenes was more prevalent in samples obtained from dairy cattle and their environment than in milk samples. Strategies to control the pathogen in dairy operations should focus on cow hygiene and sanitary milk harvesting on the farm.
Objective—To determine the duration of fecal shedding of and serologic response to Salmonella spp after natural infection in dairy calves and characterize Salmonella organisms recovered from these herds.
Animals—Calves from 2 dairy herds (A and B) in the northeast United States that were identified at the beginning of a Salmonella outbreak.
Procedures—Fecal samples were collected twice per week (herd A) or once per week (herd B); blood samples were collected for serologic testing once per week in both herds. Bacteriologic culture of fecal samples was performed, and Salmonella isolates were characterized by serotype, pulsed-field gel electrophoresis (PFGE) pattern, and antimicrobial resistance profile.
Results—All Salmonella isolates from herd A were serovar Typhimurium var Copenhagen, had the same PFGE pattern, and were resistant to at least 9 antimicrobials. All isolates from herd B were Salmonella Typhimurium, represented 2 PFGE patterns, and were susceptible to all antimicrobials evaluated. The estimated duration of fecal shedding was 14 days in herd A and 9 days in herd B. Few calves were seropositive for antibody against Salmonella lipopolysaccharide within the first week after birth (0 of 20 in herd A and 13 of 79 in herd B) or seroconverted (6 in herd A and 4 in herd B). Fecal shedding was more common in calves that seroconverted, but overall, there was not a strong association between seropositivity and fecal shedding of Salmonella organisms.
Conclusions and Clinical Relevance—Although the herds differed in serologic response and Salmonella subtype, the duration of fecal shedding among calves was similar between herds.