Feline hyperesthesia syndrome is diagnosed primarily through observation of symptoms and the exclusion of other medical conditions. Veterinarians look for signs such as skin twitching, unusual vocalizations, and erratic behavior. Diagnostic tests might include skin biopsies, blood tests, and neurological exams to rule out allergies, infections, and neurological disorders. It's crucial to differentiate these symptoms from those of other diseases that can present similarly, ensuring a correct diagnosis and appropriate treatment strategy.