Plasma concentrations of a type II collagen-derived peptide and its nitrated form in growing ardenner sound horses and in horses suffering from juvenile digital degenerative osteoarthropathy

Several breeds of draft horses suffer from degenerative digital osteoarthropathy, resulting in a reduced active lifespan. A group of 30 Ardenner horses was followed, in standardized conditions, from 15 to 28 months of age to detect the early manifestations of the disease. The severity of the disease was assessed according to a personal grading system including clinical and radiographic items. Coll 2-1, a peptide of the helical region of type II collagen, and its nitrated form (Coll 2-1 NO2) were assayed in blood plasma collected at 452 +/- 18 days, 504 +/- 20 days, 558 +/- 18 days, 613 +/- 19 days, 675 +/- 19 days, 752 +/- 21 days and 852 +/- 19 days of age. At the end of the follow-up period, 53.3% of Ardenner horses were affected by a degenerative digital osteoarthropathy. A significant effect (p < 0.05) of time, sex and pathology was observed for Coll 2-1 NO2. Variations of Coll 2-1 were not significant except for the time effect. The elevation of Coll 2-1 NO2 in the pathological group could indicate an inflammatory process during the growth of the affected horses, as nitration of tyrosine is mediated through reactive oxygen/nitrogen species and/or myeloperoxidase activity. Coll 2-1 NO2 appears to be an interesting early marker of cartilage degradation and oxidation in degenerative osteoarthropathy