Objectives

Recently, there has been an increasing prevalence of canine leptospirosis, most often due to infection with serovars grippotyphosa or pomona. The objective of thus study was to determine the clinical, serologic, histopathologic, and diagnostic features of canine leptospirosis.

Materials & Methods

Clinical findings and results of necropsy, serology, histopathology, immunohistochemical, and PCR studies were compiled for 15 cases of canine leptospirosis.

Results

Three different stages were characterized: Dogs with the acute form had mild histological lesions with renal interstitial edema and tubular necrosis and profound organ dysfunction. These dogs had no serologic evidence of leptospirosis, leptospira fluorescent antibody examination was positive, and immunohistochemical stains did not detect leptospira antigen. Dogs with subacute or "active" infections had high serologic titers, positive leptospira antibody staining, positive immunohistochemistry, and "classic" puruloplasmacytic interstitial nephritis. Dogs in the chronic stage had low leptospiral titers, variable immunohistochemical results, and chronic interstitial nephritis.

Conclusions

We propose that canine leptospirosis may occur as an acute fulminant, subacute, or chronic disease. While diagnosis of the "classic" subacute active form of the disease is relatively straightforward, leptospirosis should also be considered in dogs with acute fatal illness without the typical lesions of leptospirosis and in dogs with non-specific chronic renal disease.