Clinically healthy dogs with subclinical Leishmania infantum infection exhibit early inflammatory haematological and electrophoretical alterations

Canine leishmaniosis caused by Leishmania infantum is a vector-borne zoonotic disease with a broad clinical spectrum ranging from asymptomatic infection to severe systemic disease. Although clinicopathological alterations have been extensively described in clinically affected dogs, less information is available regarding subtle laboratory differences associated with subclinical infection in apparently healthy animals. The aim of this study was to explore whether clinically healthy dogs naturally infected with L. infantum exhibit measurable haematological, biochemical and serum protein electrophoretic differences compared with non-infected dogs. Early laboratory alterations associated with subclinical L . infantum infection remain insufficiently characterised in clinically healthy dogs. This study evaluated whether qPCR-positive asymptomatic dogs exhibit detectable inflammatory haematological and biochemical signatures. Although all laboratory values remained within reference intervals, infected dogs exhibited distinct inflammatory-associated laboratory patterns compared with non-infected animals. Infected dogs showed eosinopenia together with lower erythrocyte haemoglobin indices and increased monocyte and basophil counts. Biochemical and electrophoretic analyses revealed increased total protein and α1-, β2- and γ-globulin fractions in infected dogs, supporting the presence of early inflammatory and immune activation. These findings suggest that subclinical L. infantum infection is accompanied by detectable inflammatory laboratory alterations before overt clinical disease develops.