Impulsive, disinhibited behavior in dogs, which comes to expression as aggression, has a major impact on public health. Measures taken without a real understanding of the underlying pathology are unlikely to be effective. It would therefore be not only of pathophysiological but also of clinical relevance to develop a research paradigm to investigate this aberrant behavior in dogs. The first aim of this article is to review the literature concerning functional-anatomical and biochemical research on animal impulsivity. On the basis of this research, a hypothesis involving the prefrontal serotonin-2A receptor in the frontal cortex is generated and the feasibility of quantifying the 5-HT2A receptor with Single Photon Emission Computed Tomography (SPECT) and the highly selective receptor radioligand 123I-5I-R91150 is presented in a pilot study. If confirmed, this hypothesis may lead to the development of an in vivo research tool for investigating behavioral disorders and a modality for monitoring the effects of pharmacologic interventions and behavior therapy.