Final answer:
The condition that affects more than 50% of horses with PPID is Laminitis.
Step-by-step explanation:
The condition that affects more than 50% of horses with PPID (Pituitary Pars Intermedia Dysfunction) is Laminitis. Laminitis is a painful condition that affects the feet of horses and can result in lameness or even the inability to walk.
PPID, also known as equine Cushing's disease, is a hormonal disorder commonly found in older horses. It occurs when the pituitary gland produces an excess of certain hormones. Laminitis is a common secondary complication associated with PPID, affecting a significant majority of affected horses.Gastric ulcers can also occur in horses with PPID, but they do not affect more than 50% of horses with the condition. Therefore, the correct answer to the question is E. Laminitis.