Final answer:
The distal boundary for a caudocranial radiograph of the feline stifle is the distal 1/3rd of the tibia/fibula, to ensure a comprehensive image of the knee joint and associated anatomical structures.
Step-by-step explanation:
When taking a caudocranial radiograph of the feline stifle, the distal boundary is the distal 1/3rd of the tibia/fibula. This diagnostic imaging technique is used to view the anatomy of the knee joint in detail. The stifle, or the knee joint, in felines includes the articulation of the medial and lateral condyles of the femur with the medial and lateral condyles of the tibia. When positioning for this type of radiograph, it is essential to include the joint space of the stifle as well as the proximal and distal relations to ensure a comprehensive image. Therefore, to properly capture the region of interest, the radiograph must include the distal femur, the patella, as well as the proximal and distal aspects of both the tibia and fibula, with a focus on the distal 1/3rd.