A locomotor disorder clinically similar to spastic paresis in an adult Friesian bull.

A 5-year-old Friesian stud bull developed a progressive locomotor disorder on return to stud after a period of rest. He had defects in conformation exacerbated by poor condition. The hind limbs were excessively straight. When he stood or moved, the Achilles tendons and their associated muscles were rigid. The disorder clinically resembled spastic paresis of calves. Necropsy showed a degenerative arthropathy in all hind limb joints below the hip. Lesions were also in tendons and skeletal muscles. The M. flexor digitorum superficialis had severe type II cell atrophy with many ring, lobulated and moth-eaten type I cells.