Leishmaniosis caused by Leishmania infantum is vector-born severe enzootic disease in dogs. It includes a wide spectrum of clinical symptoms, but the most characteristic are alterations in the hematopoetic system and renal failure. Also, infected animals could be asymptomatic, so the manifestation of L. infantum infection depends on many factors, including host’s immunological status. The aim of this survey was to find parameters related with hematopoetic and renal failure (hematology, biochemical parameters - urea, creatinine, serum proteins) in symptomatic and asymptomatic dogs seropositive for canine leishmaniosis. Within the hematological parameters, we found significant differences between symptomatic and asymptomatic dogs in the erythrogram and platelet count, but not in the leukogram. Significant differences between the two groups were found also for urea, creatinine, serum albumin and globulin, but not in serum total protein and A/G ratio. These findings indicate individual variability of the host’s response to infection with L. infantum.