Changes in serological, inflammatory, and serum protein electrophoretic markers during ongoing meglumine antimoniate plus allopurinol therapy in canine leishmaniosis

Canine leishmaniosis, caused by Leishmania infantum, is a vector-borne disease in which early treatment monitoring remains challenging. This prospective study evaluated short-term changes in serological, inflammatory, and serum protein electrophoretic parameters during first-line therapy with meglumine antimoniate plus allopurinol. Eighteen dogs with confirmed clinical disease were enrolled at diagnosis, and fifteen dogs completing all follow-up visits (Days 0, 7, 14, 21, and 29) were included. Infection was confirmed by compatible clinical and/or laboratory abnormalities, high anti-Leishmania antibody levels, and successful parasite isolation. Anti-Leishmania antibodies were quantified using in-house single-dilution and two-fold serial dilution ELISA; circulating immune complexes, C-reactive protein, a complete blood count, a biochemical profile, and serum protein electrophoresis were also assessed. Both ELISA methods showed a significant decline in antibody levels during treatment, with serial dilution ELISA showing greater discrimination among highly positive samples. C-reactive protein concentrations decreased significantly from diagnosis to Day 29, indicating reduced systemic inflammation. Serum protein electrophoresis showed significant increases in albumin and the albumin:globulin ratio, along with a significant decrease in gamma globulins. Circulating immune complexes concentrations remained stable. These findings support quantitative serology, C-reactive protein, and serum protein electrophoresis as useful tools for early monitoring of therapeutic response in clinical canine leishmaniosis.