In this issue of Veterinary Clinics of North America: Equine Practice, guest editor Dr. Lais R. R. Costa brings her considerable expertise to the topic of A Problem-Oriented Approach to Immunodeficiencies and Immune-Mediated Conditions in Horses. Top experts in the field focus on a problem-oriented approach, starting with the clinical presentation, differential diagnosis, and tools to rule out other conditions to reach the final diagnosis of the immunologic condition, followed by discussion of pathogenesis, management, and treatment. Contains 15 relevant, practice-oriented topics including skin allergies of horses; approach to immune-mediated thrombocytopenia and immune-mediated hemolytic anemia; approach to equine recurrent uveitis; approach to inflammatory bowel disease; and more. Provides in-depth clinical reviews on immunodeficiencies and immune-mediated conditions in horses, offering actionable insights for clinical practice. Presents the latest information on this timely, focused topic under the leadership of experienced editors in the field. Authors synthesize and distill the latest research and practice guidelines to create clinically significant, topic-based reviews.