Dr Jennifer Stewarts Bone Formula Forte is a fortified calcium supplement for horses on hard feed. Bighead and osteoporosis are a constant risk from high phosphorus, oxalates and phytates in feeds. Some examples are cereal and grassy hays, grains, bran and sub-tropical grass (including buffel, panic, kikuyu and setaria) found throughout Australia. Signs include shifting intermittent lameness. Also reluctance to move forward freely, joint pain, creaky joints, stiffness, dental problems and an increased risk of fractures, tendon and ligament injuries.