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FRACTURE of the distal phalanx is a well-known orthopaedic condition in cattle that usually results from severe trauma to the sole of the digit ( Blowey 2008 ). Hard walking surfaces, oestrous behaviour, service, transportation, heavy bodyweight, hoof overgrowth, and weakened bone due to age or fluorosis may be predisposing factors for the disease ( Greenough and others 1981 , Blowey 2008 ). The fracture line usually runs from the solar surface of the bone to the articular surface of the distal interphalangeal joint ( Ferguson 1997 , St Jean and Desrochers 2004 , Blowey 2008 ). Fracture of the distal phalanx may also occur as a sequel to osteitis resulting from the spread of infection in cases of deep septic pododermatitis ( Ferguson 1997 ). This type of fracture is most likely to be associated with avulsion fragments of the solar surface of the bone at the site of insertion of the deep digital flexor tendon and the apical region ( Greenough and others 1981 ). Fractures of the distal phalanx that involve the extensor process of the bone have not been well documented in cattle, and occur most frequently in horses ( Honnas and others 1988 ). This report describes two cases of extensor process fractures of the distal phalanx, in a bull and a lactating cow, resulting in acute severe lameness.
Case report
Case 1
Case 1 was a six-year-old Holstein bull that had been kept in an individual pen in a breeding centre and provided semen at weekly intervals. The bull had been lame on the left forelimb for a few days and showed signs of severe pain. The affected limb was held forward and slightly inward, and much of the weight was taken by the heel ( Fig 1 ). When the bull walked, a weight-bearing lameness was apparent, and the cranial stride of the affected limb was lengthened to bear more weight on the heel. The bull often stopped to lift the affected limb, shaking it in severe pain. On clinical examination, mild swelling and tenderness over the dorsal coronet of the inner digit of the affected limb were found. The swelling became more pronounced on the second day. No visible lesions on the sole of the digit were...