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.
Objective—To determine comparative efficacy of
vaccines administered IM and intranasally, used alone
or sequentially, to protect puppies from infection with
Bordetella bronchiseptica and determine whether
systemic or mucosal antibody response correlated
Design—Randomized controlled trial.
Animals—50 specific-pathogen-free Beagle puppies.
Procedure—In 2 replicates of 25 dogs each, 14-weekold
puppies that were vaccinated against canine distemper
virus and parvovirus were vaccinated against B bronchiseptica via intranasal, IM, intranasal-IM, or IMintranasal
administration or were unvaccinated controls.
Puppies were challenge exposed via aerosol administration
of B bronchiseptica 2 weeks after final vaccination.
Clinical variables and systemic and mucosal antibody
responses were monitored for 10 days after challenge
exposure. Puppies in replicate 1 were necropsied
for histologic and immunohistochemical studies.
Results—Control puppies that were seronegative
before challenge exposure developed paroxysmal
coughing, signs of depression, anorexia, and fever.
Vaccinated puppies (either vaccine) that were seronegative
before challenge exposure had fewer clinical signs.
Puppies that received both vaccines had the least
severe clinical signs and fewest lesions in the respiratory
tract. Vaccinated dogs had significantly higher concentrations
of B bronchiseptica-reactive antibodies in
serum saliva before and after challenge. Antibody concentrations
were negatively correlated with bacterial
growth in nasal cavity and pharyngeal samples after
Conclusions and Clinical Relevance—Parenterally
and intranasally administered vaccines containing B
bronchiseptica may provide substantial protection
from clinical signs of respiratory tract disease associated
with infection by this bacterium. Administration
of both types of vaccines in sequence afforded the
greatest degree of protection against disease. (J Am
Vet Med Assoc 2001;218:367–375)