Overview
As in the forefoot, the bovine hindfoot bears weight on two main digits, III (medial) and IV (lateral), each with a proximal, middle and distal phalanx. Digits II and V are the dewclaws (accessory digits), on the plantar side of the fetlock, with one or two small bones that do not articulate with the skeleton. In the pelvic limb the lateral claw is larger and carries more load than the medial, especially during walking; this is why it is the one most often diseased.
Phalanges
- Proximal phalanx (phalanx proximalis): articulates at the fetlock with one condyle of the metatarsus and with the proximal sesamoid bones.
- Middle phalanx (phalanx media): forms the pastern joint with the proximal phalanx.
- Distal phalanx (phalanx distalis): enclosed in the claw. Its solear surface rests on the corium of the sole; on it the flexor tubercle receives the tendon of the deep digital flexor. The extensor process receives the digital extensor.
Sesamoid bones
- Proximal sesamoid bones: four per limb, two on the plantar side of each fetlock.
- Distal sesamoid bones: one per digit, plantar to the distal interphalangeal joint.
Clinical relevance
- Sole ulcer: appears at the typical site of the sole, near the heel, beneath the flexor tubercle of the distal phalanx, mostly in the lateral hind claw. Sinking of the distal phalanx within the claw compresses the corium between the bone and the sole.
- White line disease and toe necrosis: also predominate in the lateral hind claw; toe necrosis affects the tip of the distal phalanx.
- Septic pedal osteitis and septic distal interphalangeal arthritis: when these lesions become deeply infected. They can be treated by resection of the affected tissue or amputation of the digit, often with a block on the sound claw.
- Fractures of the distal phalanx: less common than in the thoracic limb.