Pathology of so-called leg weakness in the pig.

The morphologic background of the poorly defined clinical entity called leg weakness in pigs was determined. Two hundred and thirty skeletons of breeding pigs slaughtered because of leg weakness were studied. Macroscopic, radiologic, bacteriologic and histologic examinations were performed. Three main types of pathologic changes were found and defined: Osteochondrosis, osteoarthrosis and arthritis. Distribution of the changes and their interrelationship were studied as well as age, sex and breed incidence. It was concluded that osteochondrosis is the most important cause of leg weakness. In adolescent animals, manifestations of osteochondrosis were seen in joints and growth plates of almost all individuals. A high frequency of osteoarthrosis, higher with increasing age, was also found. In most animals osteoarthrosis seemed to be secondary to osteochondrosis. However, primary osteoarthrosis of the hock joint similar to spavin in the horse was found. This lesion occurred already in young animals. Chronic proliferative arthritis and discospondylitis were frequent. Suppurative arthritis and osteomyelitis due to pyemia were also common findings. Inflammatory changes were seen as complications to osteochondrosis. Arthritis was secondary to osteochondrosis in importance as the cause of leg weakness in the pig.