The presence of collagen types II and X in medial coronoid processes of 21dogs

The purpose of this study was to determine collagen type II and X immunohis tochemical staining characteristics of naturally-occurring fragmented media l coronoid processes (FMCP) in order to help delineate potential pathophysi ological events associated with FMCP. 34 surgically excised FMCP from 21 client-owned dogs and 16 intact medial c oronoid processes from 8 mongrel dogs were examined. The specimens were cat egorized by the dog's age: <12 months, 12-18 months, 18-24 months, >24 mont hs. The excised FMCP and normal medial coronoid processes were sectioned and st ained with haematoxylin and eosin, safranin-O fast green, and toluidine blu e. Sections were subjectively evaluated for tissue morphology, cell and mat rix content, and proteoglycan staining. Immunohistochemical staining was pe rformed for collagen types II and X. Sections were then subjectively evalua ted for the location and intensity of staining. FMCP tissue demonstrated a wide variety of histological and immunohistochem ical characteristics compared to normal medial coronoid processes. Signific antly (P = 0.016) more normal dogs stained positive for collagen type X tha n dogs with FMCP in the <12 months old group. No other significant differen ces between affected and normal dogs were noted for either collagen type in any age group. No significant difference in age was noted for the presence or absence of collagen type II among affected dogs, and no statistically s ignificant correlation was observed between age of those with collagens typ e X and type II present. Although not statistically significant (P = 0.100) , there was a trend for the presence of collagen type II when collagen type X was present. The results of this study have not provided a definitive an swer regarding the role of collagen type X in the etiopathogenesis of FMCP, but suggest that it may be an important factor in some cases, warranting f urther investigation.