The Syrian hamster (Mesocricetus auratus) is the best animal model for human leishmaniosis, an emergent disease that causes 400,000 new cases every year. The main objective of this assay was to prove the relationship between female lactation, which implies hyperprolactinaemia (IFN-gamma, IL-12, IL-2 and TNF-alpha elevated), and leishmaniosis (IFN-gamma, IL-12, IL-2 and TNF-alpha diminished). The results demonstrate the clear implication of lactation in immune response. The infected lactating females did not show any symptoms of sickness, a 24g mean increase was noticed, throughout the assay they were negative in the indirect diagnosis test (Direct Agglutination Test (DAT)), and in the direct diagnosis tests (N-N-N isolation, tissue impressions).