We hypothesized that renal glomerulopathy is a common finding in dogs with subclinical ehrlichiosis, and pro-inflammatory cytokines may be associated with renal injury. The aim of this study was to evaluate renal cortex biopsies in 15 dogs with subclinical ehrlichiosis diagnosed by PCR and enzyme-linked immunosorbent assay (ELISA) and in 17 healthy dogs as a control group. Dogs with presence of clinical signs, comorbidities and/or azotemia were excluded. Biopsy material was examined by light microscopy (LM). Sections were stained with hematoxylin and eosin, periodic acid-Schiff, Jones methenamine silver, Masson's trichrome, and Congo red. Cytokine quantification of tumor necrosis factor alpha (TNF-α), interferon gamma (INF-γ) and interleukin 6 were assessed through ELISA using commercial kits specific to dogs (MILLIPLEX®), according to the manufacturer's instructions. LM abnormalities were identified in 14 dogs (93.3%) from the ehrlichiosis group, but most findings were subtle. Mesangial cell proliferation (40.0%), synechiae (40.0%), globally sclerotic glomeruli (33.3%), ischemic glomeruli (33.3%), focal segmental glomerulosclerosis (FSGS) (33.3%), focal thickening of the glomerular basement membranes (26.7%), hydropic degeneration (26.7%), and interstitial fibrosis and tubular atrophy (IFTA) (20.0%) were frequent.

Cytokines were increased in subclinical phase on levels of TNF-α, INF-γ, and IL-6 in comparison to control. These results suggest that TNF-α, INF-γ and IL-6 may be involved in the pathogenesis of tubule-glomeruli injury and subclinical ehrlichiosis may lead in chronic kidney disease (acknowledgement to FAPESP for financial support - #2014/21506-2).