Flea allergy dermatitis is the most common skin disease in dogs worldwide, causing intense itching from an immune reaction to flea saliva that goes far beyond what non-allergic dogs experience.
Dogs with FAD experience intense, sustained itching from each flea bite - an allergic reaction that persists for days and is qualitatively different from the transient discomfort of a normal flea bite. The itching drives compulsive scratching, biting, and rubbing that causes self-trauma: hot spots, abraded skin, secondary bacterial infections, and hair loss. Many FAD dogs cannot sleep normally during flare-ups, and the constant urge to scratch dominates their waking life. The behavioral frustration of unrelievable itching - an itch that cannot be scratched away - causes measurable distress. FAD is entirely manageable with modern prescription flea prevention, making every FAD flare-up in a treated dog a treatment failure requiring attention.