In this chapter, we describe psychiatric disorders related to the dysregulation of the fear axis. We present sensory deprivation syndrome, categorical phobias, and post-traumatic phobias. The so-called categorical phobias include social phobias, healthcare phobia, noise phobia, and transport phobia, among others. Due to its position in the food chain, being both a predator and prey, the cat is an animal quickly overwhelmed by fear. Its reactions are often highly amplified, and the clinician must be vigilant to distinguish between different disorders. For each disorder, the clinical presentation, diagnosis, treatment, prognosis, and follow-up are detailed, and clinical vignettes illustrate the challenges and particularities of fear expression in cats.