Objective—To characterize Pasteurella spp isolated
from healthy pack goats and evaluate the effects of
administration of a commercial Pasteurellavaccine.
Procedure—Pharyngeal swab specimens and blood
samples were collected on day 0 before vaccination
with a Pasteurella (Mannheimia) haemolytica
serotype A1 bacterin. Samples were also collected
from 17 goats on days 21 and 35. Isolated Pasteurella
spp were assigned to biovariant groups on the basis
of results of biochemical utilization tests and
serotyped. Serum antibody titers were determined.
Results—Multiple strains of Pasteurellaspp were isolated
from swab specimens and assigned to 30 nonhemolytic
and 14 β-hemolytic biovariant groups. The
most common biovariant isolated was nonhemolytic
P trehalosi belonging to group 2. This strain was isolated
from 41 goats. Nonhemolytic
P haemolytica strains were isolated from 31 goats,
whereas β-hemolytic strains of P trehalosi and
P haemolytica were isolated from 8 and 35 goats,
respectively. Vaccination with the A1 serotype did not
affect the proportion of goats from which we isolated
each biovariant group or the number of biovariant
Conclusion and Clinical Relevance—Multiple
strains of P haemolytica and P trehalosi belonging to
nonhemolytic and β-hemolytic biovariant groups were
isolated from the pharynx of healthy domestic pack
goats. Because hemolytic activity correlates with
leukotoxin production, β-hemolytic strains may have a
greater potential to cause disease in naive populations
of wild ruminants. However, vaccination with an A1
serotype bacterin did not decrease the proportion of
culture-positive goats. (Am J Vet Res 2002;63:119–123)
Objective—To elucidate the species and biovariants of Pasteurellaceae isolated from clinically normal bighorn sheep (Ovis canadensis) or bighorn sheep with evidence of respiratory disease.
Sample—675 Pasteurellaceae isolates from 290 free-ranging bighorn sheep in Idaho, Oregon and Wyoming.
Procedures—Nasal and oropharyngeal swab specimens were inoculated onto selective and nonselective blood agar media. Representatives of each colony type were classified via a biovariant scheme. The association of respective β-hemolytic isolates with respiratory disease was evaluated via χ2 analyses.
Results—Bacterial isolates belonged to 4 species: Histophilus somni, Mannheimia haemolytica, Pasteurella multocida, and Bibersteinia (Pasteurella) trehalosi. Within the latter 3 species, 112 subspecies, biotypes, and biovariants were identified. Bibersteinia trehalosi 2 and B trehalosi 2B constituted 345 of 675 (51%) isolates. Most (597/618 [97%]) isolates from adult sheep were from clinically normal animals, whereas most (47/57 [82%]) isolates from lambs were from animals with evidence of respiratory disease. Twenty-two Pasteurellaceae biovariants were isolated from sheep with respiratory disease; 17 of these biovariants were also isolated from clinically normal sheep. The ability of isolates to cause β-hemolysis on blood agar was associated with respiratory disease in adult bighorn sheep (OR, 2.59; 95% confidence interval, 1.10 to 6.07).
Conclusions and Clinical Relevance—Bighorn lambs appeared more susceptible to respiratory disease caused by Pasteurellaceae than did adult sheep. β-Hemolytic Pasteurellaceae isolates were more likely to be associated with respiratory disease than were non–β-hemolytic isolates in adult sheep. Identification of Pasteurellaceae with the greatest pathogenic potential will require studies to estimate the risk of disease from specific biovariants.