Variation in intervertebral disc serine proteinase inhibitory proteins with ageing in a chondrodystrophoid (beagle) and a non-chondrodystrophoid (greyhound) canine breed.

Intervertebral disc (IVD) proteoglycans (PGs) and trypsin inhibitory protein levels were assessed for groups of beagles and greyhounds aged between 4 and 80 months. A significant age-dependent decline in PGs and in trypsin inhibitory protein levels was evident in extracts of the beagle nucleus pulposus (NP). This was confirmed for the semi-purified trypsin inhibitor, using Western blotting. These age changes, however, were not evident in the greyhound NP. Furthermore, no significant ageing trends in PG or trypsin inhibitory protein levels were evident in extracts of the annulus fibrosus of either animal. The early onset of IVD degeneration in the beagle, a canine breed of the chondrodystrophoid (achondroplastic) classification, may be related to this decline in the anti-catabolic effects of the endogenous serine proteinase inhibitory proteins.