Heart rate of DNA-immunized dogs with experimental T. cruzi infection. Heart beat recordings from each experimental group (plasmid DNA immunized- and SS mock-immunized dogs) were compared with those of the control group (uninfected healthy animals). Heart rates exceeding 160 beats per minute were considered tachycardic. The values represent the average of the heart rate recordings ± S.D. Two-way ANOVA statistical test (* P ≤ 0.05).