Complement C3 in Bernese Mountain dogs

 Background: Previous research suggests that low serum concentrations of
the third component of complement (C3) are associated with both the
susceptibility to infectious agents such as Borrelia burgdorferi and the
development of glomerular disease. We hypothesized that low levels of C3
are associated with the coincident occurrence of B. burgdorferi
infection and glomerulonephritis in Bernese Mountain dogs.
Objectives: The aims of this study were to evaluate the serum
concentration of C3 in Bernese Mountain dogs with and without antibodies
against B. burgdorferi and to compare this concentration with that of
healthy control dogs.
Methods: Eighty-three clinically healthy Bernese Mountain dogs and 46
control dogs were included. Antibodies against B. burgdorferi were
determined using an ELISA with a whole cell sonicate as antigen. Results
were confirmed using Western blot. C3 was measured using a single radial
immunodiffusion test.
Results were reported as the percentage concentration of C3 compared
with that in pooled preserved canine serum (100% C3 concentration).
Results: Median C3 concentration was 128.5% in Bernese Mountain dogs
with antibodies against B. burgdorferi, 133.5% in B.
burgdorferi-negative Bernese Mountain dogs, 87.8% in positive control
dogs, and 102.2% in negative control dogs. Within Bernese Mountain and
control groups, C3 was lower in dogs with antibodies against B.
burgdorferi compared with those without. Percentage concentration of C3
was higher in healthy Bernese Mountain dogs compared with control dogs.
Conclusion: Low C3 concentration is not an explanation for the high
prevalence of B. burgdorferi infections and glomerular disease in
Bernese Mountain dogs.