Evaluation of Three Serological Tests for Diagnosis of Canine Brucellosis

Canine brucellosis caused by Brucella canis, is an infectious disease affecting dogs and wild Canidae. Clinical diagnosis is challenging, and laboratory testing is crucial for a definitive diagnosis. Various serological methods have been described, but their accuracy is uncertain due to limited validation studies. The present study aimed to evaluate the performances of three serological tests for the diagnosis of B. canis in comparison with bacterial isolation (gold standard), in order to establish a protocol for the serological diagnosis of canine brucellosis. A panel of sera from naturally infected dogs (n = 61), from which B. canis was isolated, and uninfected dogs (n = 143), negative for B. canis isolation, were tested using microplate serum agglutination (mSAT), complement fixation performed using the Brucella ovis antigen (B. ovis-CFT), and a commercial immunofluorescence assay (IFAT). The sensitivity and specificity of the three serological methods were, respectively, the following: 96.7% (95% CI 88.8-98.7%) and 92.3 (95% CI 86.7-95.1%) for mSAT; 96.7% (95% CI 88.8-98.7%) and 96.5 (95% CI 92.1-98.2%) for B. ovis-CFT; 98.4% (95% CI 91.3-99.4%) and 99.3 (95% CI 96.2-99.8%) for IFAT. The use in of the three methods in parallel, combined with bacterial isolation and molecular methods, could improve the diagnosis of the infection in dogs.