PATHOLOGICAL AND RADIOLOGICAL INVESTIGATIONS ON OSTEOCHONDROSIS IN PIGS, ASSOCIATED WITH LEG WEAKNESS

Two-hundred and seventy-eight Danish Landrace boars were examined radi ologically and pathologically for osteochondrosis and other joint lesi ons on the left legs at slaughter (95 kg). The joint changes were scor ed on a scale from 1 (normal) to 5 (very severe changes/osteochondriti s dissecans). The correlations between radiological and pathological s cores were highly significant in the humeral condyles (r = 0.66, P < 0 .001), the distal ulna growth plate (r = 0.51, P < 0.001), the femoral condyles (r = 0.33, P < 0.001) and hock (distal tibia (r = 0.17, P < 0.01) and the medial trochlear ridge of the talus (r = 0.17, P < 0.01) , indicating that radiographical examination is a useful method for di agnosing osteochondrosis in live pigs. Thickening of cartilage was str ongly associated with subchondral lesions in the three predilection si tes: the humeral condyle, the femoral condyles and the distal ulna gro wth plate. Osteochondritis dissecans (OCD) in the humeral condyles was significantly associated with subchondral lesions (<(OR)over cap> = 1 .86; P < 0.001), but not with cartilage thickness when analysed simult aneously.There were no associations between lesions in the distal ulna growth plate, the humeral condyles, the femoral condyles or the ancon eal process. There was no significant correlation between OCD in the h umeral condyles and the anconeal process. Osteochondrosis could theref ore not be stated to be a generalized disorder. Regression coefficient s between joint changes and leg weakness symptoms judged before slaugh ter were very small and showed no clear trends. OCD in the humeral con dyles was, however, significantly associated with 'legs turned out on fore (<(OR)over cap> = 2.48; P < 0.001) and hind (<(OR)over cap> = 1.6 2; P < 0.05) legs', and OCD in the anconeal process with 'stiff moveme nt in front' (<(OR)over cap> = 2.01; P < 0.05). Osteochondrosis is thu s comparable with a threshold trait, where the threshold is the develo pment of an OCD in an osteochondrosis injured joint.