A: These terms are similar in meaning; however, technically, they are different.
Caudal heel pain is typically used to describe pain from the heel or back of the foot. A horse with caudal heal pain would respond positively to a palmar digital nerve block. The navicular structures are often included, but the horse could also have pain associated with other structures.
Navicular disease is usually used to describe disease that has caused radiographic changes to the navicular bone.
Navicular syndrome is more encompassing to describe lesions associated with the navicular soft-tissue structures and may not have radiographic abnormalities.
Having said this, all three terms are commonly used interchangeably depending on veterinarian preference.