Clinical performance of 3 commercially available point-of-care antibody tests for Brucella canis in dogs.

BACKGROUND

Brucellosis in dogs, caused by Brucella canis, is a zoonotic disease often underdiagnosed because of diagnostic challenges and subclinical infection. Bacterial culture, the reference standard, is impractical and has limited sensitivity because of intermittent or low-grade bacteremia. Accurate point-of-care (POC) testing could facilitate timely management and infection control.

HYPOTHESIS/

OBJECTIVES

Evaluate the diagnostic performance of 3 POC lateral flow assays for detection of B. canis antibodies in dogs, using the Canine Brucella Multiplex (CBM) assay as the reference serologic assay.

ANIMALS: Fifty serum samples from 50 client-owned dogs submitted for B. canis serology.

METHODS

Samples were classified as CBM-positive (n = 10; culture-positive dogs) or CBM-negative (n = 40; healthy dogs undergoing export testing). Assays were run in duplicate and independently interpreted by 2 observers. Positive percent agreement (PPA), negative percent agreement (NPA), and inter-reader agreement were calculated relative to CBM.

RESULTS

The Anigen Rapid C.Brucella Ab assay demonstrated 90.0% PPA (95% CI, 55.5-99.8) and 100% NPA (95% CI, 91.1-100). The FASTest® BRUCELLA canis assay demonstrated 100% PPA (95% CI, 69.1-100) and 92.5% NPA (95% CI, 79.6-98.4). The Canine Brucella LPS Antibody Rapid Test demonstrated 0% PPA (95% CI, 0-30.9) and 97.5% NPA (95% CI, 86.8-99.9). Inter-reader agreement was almost perfect for all assays (κ = 0.81-1.00).

CONCLUSIONS AND CLINICAL

IMPORTANCE

The Anigen Rapid C.Brucella Ab and FASTest® BRUCELLA canis assays showed good agreement with the CBM assay and may be useful rule out tests in dogs with clinical signs compatible with brucellosis. In low prevalence settings, positive results require confirmatory testing, and false negatives remain possible.