Methods, pharmaceutical formulations, and kits are provided for using neurokinin 2 receptor agonists to effectuate voluntary “on-demand” voiding of urine and feces in mammals who cannot void without external invasion of the bladder and bowel or those who void involuntarily (i.e., those having urinary and/or fecal incontinence). The pharmaceutical formulations and kits can also be useful for inducing voiding of urine and defecation in mammals that do not have a voiding dysfunction such as, for example, in a person who is comatose and may void unconsciously or in a pet at a convenient location at a specific time. The methods and compositions provide patients with voiding dysfunction control over when and where they void.