Diagnosis of Lyme’s disease is challenging and normally depends on evidence of exposure along with clinical signs and diagnostic tests.
Tests for Borrelia burgdorferi can be divided into those that demonstrate presence of the organism, and antibody tests.
Detection of the organism by culture, cytology, or polymerase chain reaction (PCR) assay can be difficult as the organism is difficult to culture and very rarely found in blood, urine, joint fluid or CSF.
Serological testing is helpful, but subclinical infections can occur, and antibodies to B. burgdorferi may cross react with other spirochaetes. A positive serological test does not equate to a diagnosis of Lyme disease, but animals with clinical Lyme disease are unlikely to be negative for anti-Borrelia antibodies.
The cytological changes in synovial fluids from dogs with Lyme disease are often more typical of low-grade immune-mediated joint disease than of a bacterial infection.