Lyme nephritis is a poorly understood disease of dogs characterized by renal proteinuria, Borrelia burgdorferi seropositivity, and a rapid and frequently fatal progression. Early identification of the disease has been suggested to have the potential to improve outcomes. Current recommendations include annual B. burgdorferi antibody screening of apparently healthy dogs in endemic regions, followed by evaluation of proteinuria in positive dogs in an attempt to identify early cases of Lyme nephritis. However, evidence to support this recommendation is lacking. The proposed study is designed to address the question of whether screening asymptomatic B. burgdorferi dogs for proteinuria allows for identification of those with early Lyme nephritis. The study methodology is a multi-center cross-sectional design comparing the prevalence of pathologic proteinuria between apparently healthy B. burgdorferi positive and B. burgdorferi negative client-owned dogs. Screening for B. burgdorferi will be done via the Idexx SNAP 4Dx Plus test kit, Abaxis VetScan Rapid Test/Flex4 Rapid Test kit, or Antech AccuPlex4 test platform, while proteinuria will be assessed via a hybrid staged approach utilizing urine dipsticks and urine specific gravity, followed by urinalysis and urine protein to creatinine ratio assessment when indicated.