Date Published: February 28, 2008
Publisher: BioMed Central
Author(s): Rikke K Kirk, Bente Jørgensen, Henrik E Jensen.
Joint lesions occur widespread in the Danish sow population and they are the most frequent cause for euthanasia. Clinically, it is generally impossible to differentiate between various types of non-inflammatory joint lesions. Consequently, it is often necessary to perform a post mortem examination in order to diagnose these lesions. A study was performed in order to examine the relation of abnormal gait and posture in sows with specific joint lesions, and thereby obtaining a clinical diagnostic tool, to be used by farmers and veterinarians for the evaluation of sows with joint problems.
The gait, posture and lesions in elbow- and knee joints of 60 randomly selected sows from one herd were scored clinically and pathologically. Associations between the scorings were estimated.
The variables ‘fore- and hind legs turned out’ and ‘stiff in front and rear’ were associated with lesions in the elbow joint, and the variables ‘hind legs turned out’ and ‘stiff in rear’ were associated with lesions in the knee joint.
It was shown that specified gait and posture variables reflected certain joint lesions. However, further studies are needed to strengthen and optimize the diagnostic tool.
Joint lesions are a major cause of euthanasia and culling of sows in Denmark and are of importance both economically and in relation to animal welfare . Joint lesions of sows are frequent causes of leg weakness, and non-inflammatory joint diseases as arthrosis and osteochondrosis are main causes of lameness [2-4]. Osteochondrosis developes in growing animal and is due to a failure in the endochondrale ossification of the articular cartilage and the growth plate . The lesions caused by osteochondrosis can heal completely  or progress into secondary arthrosis in the adolescent animal . The aetiology of osteochondrosis is thought to be multifactorial, and trauma, heredity, rapid growth, nutrition, and anatomical conformation are factors associated with this disease [5-7]. Non-osteochondrosis-related arthrosis (i.e. primary arthrosis) is characterized by fibrillation and ulceration of the articular cartilage and of eburnation of the subchondral bone . The pathogenesis of primary arthrosis of sows is not well understood, but the confinement of sows and the subsequent limitations of exercise have been suggested as a possible aetiology . Osteochondrosis and arthrosis in sows are often bilateral and symmetrical and are frequently observed in the distal humerus and femur .
Joint lesions were observed more often in the elbow joint compared to the knee joint (Tables 1 and 2). The most frequent lesion in the elbow joint was erosion of the articular cartilage, in particular on the medial humeral condyle (left side 95%, and right side 84%). Also ulceration (left side 18%, right side 10%) and repair (left side 13%, right side 16%) of the articular cartilage of the medial humeral condyle, as well as formation of marginal osteophytes of processus anconeus (left side 14%, right side 16%) of ulna were often observed. In the knee joint, erosion (left side 15%, right side 42%) and ulceration (left side 10%, right side 6%) of the articular cartilage of the medial femoral condyle were noted as the most frequent lesions.
Correlations between various lesions on the same articular surfaces and between lesions of opposing articular surfaces in the elbow and knee joints were observed. It was not obvious from the correlations which types of lesions preceded the other ones. However, because histology revealed erosions of the articular cartilage without ulcerations (Fig. 2a), it was most likely that erosions preceded ulcerations. An exception from this was in cases of osteochondritis dissecans, where ulceration was seen without erosion being present (Fig. 2b).
In the present study it was shown that some defined gait and posture variables reflected specific joint lesions in sows. Presence of ‘stiff in front and rear legs’ and ‘forelegs turned out’ were highly indicative of osteochondrotic and arthrotic lesions in the elbow joint. These observations could be helpful in the selection procedure of breeding animals and should encourage farmers to include animals with a low incidence of osteochondrosis in breeding programmes. However, further studies are needed to further strengthen and optimize the diagnostic tool.
The author(s) declare that they have no competing interests.
BJ designed the study and developed the gait and posture scoring methods. RKK examined and scored the joint lesions with assistance from HEJ. RKK and BJ performed the statistical analysis and RKK, BJ, and HEJ drafted the manuscript. All authors read and approved the final manuscript.