ABSTRACT Purpose To verify the effect of dog intervention on the regular session of speech therapy for developmental stuttering in adults. Methods The study involved young adults and adults with developmental stuttering. The study sample was composed of eight participants, six males and two females, ranging in age from 16 to 45 years. Participants were divided into two groups: G1 – those who underwent treatment for stuttering with the presence of a dog-therapist in the therapy room and G2 – those who underwent treatment for stuttering without the presence of the dog therapist. We included a control group, G3, composed of fluent participants, matched in age and sex to G1 and G2 to control the natural variability of speech fluency. Results Comparative results between the groups indicated that the group that performed the treatment without the presence of the dog achieved better performance, evolution and efficacy rates. Conclusion for the population in this study, the dog intervention on speech therapy did not improve treatment.