The King Charles Spaniel carries several significant hereditary health concerns. Mitral valve insufficiency (heart disease) is common and worsens with age; patent ductus arteriosus (PDA) is another documented cardiac condition. Syringomyelia — a serious spinal condition — occurs in the breed. Additional concerns include patellar luxation, retinal dysplasia, hydrocephalus, and Legg-Calvé-Perthes disease. Prospective buyers should ask breeders for OFA clearances on hips, heart, and thyroid, CERF eye certification, and confirmation of a CHIC number. Cardiac screening of breeding dogs by a board-certified cardiologist is strongly recommended. Lifespan is 10 to 12 years.