IgG avidity index and complete blood count as biomarkers of clinical disease in naturally infected dogs with Leishmania infantum

Abstract Canine visceral leishmaniosis (CVL), a parasitic disease caused by Leishmania infantum , may evolve to a chronic condition and lead to death. Evaluation of infected dogs is important to establish the clinical and laboratory parameters involved in the evolution of the disease. The objectives of the present study were to discriminate a canine population ( n  = 52) into sub-clinical and clinically affected dogs based on signs and scores, to evaluate the hematological, biochemical, histopathological and parasitological parameters of the two dog groups, and to analyze the results by multivariate regression analysis with the aim of establishing biomarkers of CVL clinical disease. The most common signs observed in the clinically affected dogs ( n  = 29) were hyperkeratosis, weight loss, onychogryphosis, pale mucosa and lymphadenomegaly. In the multivariate analysis, animals presenting high IgG avidity index and low red blood, lymphocyte and eosinophil counts, and low serum urea concentration had an increased probability of being classified as clinically affected ( p Anaplasma platys , Babesia canis vogeli , Ehrlichia canis and Hepatozoon canis . Therefore future studies should evaluate the influence of such co-infections on the associations studied using multivariate methods with larger samples.