By Blowey, R., 15th International Symposium & 7th Conference on Lameness in Ruminants, 2008
Description
During a farm lameness investigation it became apparent that many chronically lame cows had developed a swelling on the lower rib cage. Similar swellings have since been seen on many chronically lame cows on other farms elsewhere. The swelling can be palpated one hand breadth directly caudal to the elbow (the olecranon), is usually on the 7th or 8th rib, boney to palpate, non painful and non fluctuating. At post mortem the swelling is at the costo chondral junction or on the cartilaginous portion of the rib, and appears as a fracture. In some cows the affected rib is also displaced laterally, such that the whole rib protrudes from the rib case. On many cows the swelling is bilateral, even though the lameness is unilateral. Lesions are seen in chronically lame cattle, rather than acute lameness, and this suggests that a prolonged period of trauma is required to produce the dislocation. The precise cause has not been determined, although it is well known that when lying down, lame cattle drop onto the floor surface more rapidly than non lame animals, the latter slowly lowering themselves into a lying position. It is postulated that this sudden drop puts pressure onto the rib cage, and as ribs 7 and 8 are amoung the more pronounced, then it is these ribs that take the full force of the drop. There may also be additional trauma from the front foot, because this foot is adjacent to the rib cage as the cow drops.
During a farm lameness investigation it became apparent that many chronically lame cows had developed a swelling on the lower rib cage. Similar swellings have since been seen on many chronically lame cows on other farms elsewhere. The swelling can be palpated one hand breadth directly caudal to the elbow (the olecranon), is usually on the 7th or 8th rib, boney to palpate, non painful and non fluctuating. At post mortem the swelling is at the costo chondral junction or on the cartilaginous portion of the rib, and appears as a fracture. In some cows the affected rib is also displaced laterally, such that the whole rib protrudes from the rib case. On many cows the swelling is bilateral, even though the lameness is unilateral. Lesions are seen in chronically lame cattle, rather than acute lameness, and this suggests that a prolonged period of trauma is required to produce the dislocation. The precise cause has not been determined, although it is well known that when lying down, lame cattle drop onto the floor surface more rapidly than non lame animals, the latter slowly lowering themselves into a lying position. It is postulated that this sudden drop puts pressure onto the rib cage, and as ribs 7 and 8 are amoung the more pronounced, then it is these ribs that take the full force of the drop. There may also be additional trauma from the front foot, because this foot is adjacent to the rib cage as the cow drops.
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