Clinical and pathological features of the Porcine Ulcerative Dermatitis Syndrome (PUDS)

The nomenclature of ulcerative dermatitis as used in literature is somehow confusing because on the one hand this skin disorder is associated with bacterial growth and on the other hand it is a synonym for a chronic sporadic disease of adult sows with unknown aetiology. Thus, we propose the terminus 'Porcine Ulcerative Dermatitis Syndrome (PUDS)' for the latter to distinguish between these two disease complexes. This syndrome could be identified by clinical and pathological examinations in six sows, that were submitted to the clinic. Epidermal ulcers could be found nearly all over the body, but teats were always spared. Haematological examination showed a slight anaemia but physiological leucocyte counts. However, lymphopenia (x = 44.8%), granulocytosis (x = 42.0%) and an increased number of monocytes (x = 13.1%) could be found. Histologically, a lymphoplasmacytic and granulohistiocytic infiltration in the corium was most prominent. In some cases, a moderate leucocytoclastic vasculitis and perivasculitis could be seen at the dermo-epidermal border. Additionally, a multifocal interstitial nephritis with lymphoplasmacytic infiltration was a prominent feature in all animals. Participation of an immune complex associated disorder can be assumed when regarding histological findings as skin lesions in combination with glomerulonephritis are a common feature of such diseases. Also, IgG levels were elevated two- to fourfold in all affected sows when compared with healthy control pigs. This supports the hypothesis that not only T cells, as shown previously, but also the humoral branch of the immune system is involved in the aetiology of PUDS.