Effect of specific treatment on the intensity of lesions or cytokine expression in the heart tissue of dogs infected with Trypanosoma cruzi. Dogs were inoculated with 2,000 trypomastigotes per kg of body weight of the Y strain and treated with RAV at 12 mg/kg b.i.d. (q12h) for 90 days or BZ at 7 mg/kg b.i.d. (q12h) for 60 days; infected and untreated (infected control [IC]) and noninfected control (NIC) groups were also evaluated. IFN-γ (A) and IL-10 (B) mRNA expression in the right atrium was evaluated by semiquantitative reverse transcription-PCR 180 days posttreatment. Morphometric and histopatology analyses were performed with hematoxylin-eosin staining for inflammation quantification (C, E, F, G, and H) and Masson's trichrome staining for collagen quantification (D, I, J, K, and L). Magnifications, ×40. a, b, and c, different letters indicate a significant difference (P < 0.05).