THE SEQUELAE OF DISTAL ULNA PHYSEAL DYSCHONDROPLASIA (OSTEOCHONDROSIS) LESIONS IN BREEDING SWINE - A RADIOLOGICAL INVESTIGATION IN DANISH LANDRACE PIGS

A radiological follow-up study of osteochondrotic lesions in the dista l ulna was carried out in 58 Danish Landrace breeding sows for a perio d of 15 months (October 1992 to December 1993). This was part of a maj or project involving the radiological investigation of articular-epiph yseal and physeal development to investigate osteochondrotic lesions i n pigs. The radiological lesions were graded from 1 to 5 with increasi ng severity. It was observed that not all pigs passed through all grad es. Only 21 % of the pigs had no radiological osteochondrotic lesions (grade 1) during the first radiography series. After 5-7 months, the n umber of pigs without osteochondrotic radiological lesions were observ ed to have increased dramatically (21-69 %), but the converse was true for grades 2 (mild), 3 (moderate), 4 (severe) and 5 (very severe): (3 3-17 %), (21-9 %), (19-5 %) and (7-0 %) respectively. This was observe d with increasing age and weight. The 3rd radiography series indicated that the percentage of pigs without osteochondrotic lesions increased up to 82 %, and that grades 2, 3, and 4 had fallen to 14 %, 2 % and 2 % respectively, while grade five remained at 0 %. This indicated that the distal ulna osteochondrotic lesions can be important in breeding pigs during the period of growth before first pregnancy. During the fi rst pregnancy the osteochondral ossification fault can be corrected, a nd the lesions heal. The ulna growth plates were not closed at the sec ond, but mostly closing during the third radiography series.