Porcine dermatitis and nephropathy syndrome. clinical and pathological features of cases in the United Kingdom (1993-1998).

This paper documents the salient clinical and pathological features of porcine dermatitis and nephropathy syndrome (PDNS) in 96 pigs submitted from 55 units in the UK from 1993 to 1998. This series of cases pre-dated the emergence of post-weaning multisystemic wasting syndrome (PMWS) in the UK. The morbidity during outbreaks was 1% or less. Affected pigs ranged from 14 to 70 kg in weight and most died after a short clinical illness. Fifty-five pigs had multifocal or coalescing erythematous skin lesions, some progressing to dermal necrosis. Biochemistry showed raised serum urea, creatinine and gamma globulin levels accompanied by proteinuria. All cases showed bilateral renal enlargement with petechiae throughout the cortices. Microscopically these renal lesions ranged in chronology from acute necrotizing glomerulitis and vasculitis with multiple hyaline casts in renal tubules to chronic glomerular sclerosis with interstitial inflammation and fibrosis. Haemorrhagic dermatitis when present was associated with necrotizing vasculitis in the dermal vessels. Vasculitis was sometimes detected in other tissues including subcutis, lymph nodes, spleen, liver, joint synovial membrane, gastric and intestinal submucosa or serosa and meninges but its frequency and distribution varied considerably in individual pigs. Immunostaining showed deposits of IgG and IgM in damaged glomeruli, renal casts and skin lesions. The aetiology and pathogenesis of the condition remain unknown but the histopathological and immunological findings suggest a systemic immune-complex disorder resulting in vasculitis with particular predilection for kidney and skin.