Respiratory disease in kennelled dogs: serological responses to Bordetella bronchiseptica lipopolysaccharide do not correlate with bacterial isolation or clinical respiratory symptoms

Abstract

The role of Bordetella bronchiseptica in a natural outbreak of canine infectious respiratory disease was investigated both by culture and serological analysis. B. bronchiseptica was found in the lungs of a large proportion of clinically healthy dogs and in a greater proportion of dogs with respiratory disease. Using a lipopolysaccharide (LPS) antigen-based enzyme-linked immunosorbent assay, we analyzed the serological responses of a large number of dogs. Dogs with high antibody levels showed no protection from disease, and there was no correlation between the development of disease and rising antibody titer. Similarly, there was no difference in antibody levels in dogs with and without B. bronchiseptica in the lungs. Antibodies to LPS have no predictive value in determining which animals will contract respiratory disease, how severe the disease will be, or which dogs will have B. bronchiseptica colonizing the lungs.

FIG. 1.

Antibody titers do not alter between days 1 and 21. LPS antibody levels of dogs on days 1 and 21 (day 1, n = 424; day 21, n = 156) in the kennel are shown. Any samples with levels above the cutoff point of 1,452 antibody units were deemed to be positive. For clarity, the y axis has been limited to 10,000 U.

FIG. 2.

Antibody titers do not differ between healthy (H; day 1, n = 286; day 21, n = 18), diseased (D; n = 119), and convalescent (C; n = 19) dogs. LPS antibody levels in dogs on days 1 and 21, separated according to the disease statuses of the animals on day 21, are shown. Any samples with levels above the cutoff point of 1,452 antibody units were deemed to be positive. For clarity, the y axis has been limited to 10,000 U.

FIG. 3.

Percentage of dogs with either low (89 of 101 dogs) or high (49 of 55 dogs) antibody levels on day 1 which developed disease by day 21. High antibody titers offer no protection from disease.

FIG. 4.

B. bronchiseptica isolation and disease. The percentages of dogs with lung cultures positive for B. bronchiseptica (Bb) are shown (no symptoms, n = 54; mild disease, n = 26; moderate disease, n = 47; severe disease, n = 25). B. bronchiseptica is isolated with higher frequency from animals with symptoms of moderate disease.