This review deals with the neurocircuitry of fear and anxiety disorders, with the focus on neuroanatomyand neurochemistry. This knowledge is required to correctly diagnose and treat dogs with anxiety-relatedbehavioral disorders.Research to date has shown the involvement of the frontal cortex, the amygdala, the thalamus and thehippocampus as core regions in regulating fear. Imbalances (hyper- or hypoactivation) in this fear circuitrycan trigger inappropriate fear responses, i.e. anxiety disorders.Serotonin, dopamine and norepinephrine are the main neurotransmitters of emotion in the brain, butgamma-aminobutyric acid (GABA), glutamate, and the hypothalamic-pituitary-adrenal (HPA) axis producingglucocorticoids are also important in the neurochemistry of anxiety.