Porcine Dermatitis and Nephropathy Syndrome (PDNS)
|PCV2 is thought to play a role in Porcine Dermatitis and Nephropathy Syndrome (PDNS) cases such as these. Skin lesions are typically raised, red-to-purple, irregular in shape, and have a black center. Kidneys typically are enlarged and "waxy" in appearance and hae petechial hemorhages on the surface of the cortex.
PDNS is characterized clinically by acute onset of skin lesions (raised purple skin lesions progressing to multifocal raised red scabs with black centers most prominent on the rear legs), fever, and lethargy and is almost always fatal. Macroscopically, there are enlarged tan waxy kidneys with white foci and streaks. Microscopically, there is systemic vasculitis with dermal and epidermal necrosis and necrotizing and fibrinous glomerulonephritis. The microscopic hallmark lesions of PDNS, generalized vasculitis and glomerulonephritis, are suggestive of a type III hypersensitivity reaction which is characterized by deposition of antigen-antibody aggregates or immune complexes at certain tissue sites. Many pathogens including viruses (PRRSV; Choi and Chae, 2001; Thibault et al., 1998) and bacteria such as Pasteurella multocida, Streptococcus suis type 1 and 2, E. coli, Proteus sp., Haemophilus parasuis, APP, Bordetella bronchiseptica, Arcanobacterium pyogenes, Staphyloccoccus aureus, or Salmonella sp. (Thomson et al., 2002) have been implicated in the etiology of PDNS. Lainson et al. (2002) further differentiated Pasteurella multocida isolates from PDNS cases and from cases without PDNS by pulsed-field gel electrophoresis and found a single Pasteurella multocida variant associated with PDNS. PDNS was first associated with PCV2 in 2000 (Rosell et al., 2000). Allan et al. (2000) investigated PDNS cases submitted in Northern Ireland in 1990 when PRRSV had not been introduced into the area and found granulomatous lymphadenitis associated with PCV2 antigen in affected pigs.
There are two forms of PDNS described: the sporadic form and the epizootic form. With the sporadic form the mortality is rarely above 0.5%. The epizootic form was first observed in 1999 in England, when there was a sudden, marked increase of PDNS cases (Thomson et al., 2000, 2002). The within-herd mortality was reported to range from 0.25-20% and similar observations were made in the Netherlands (Elbers et al., 2000; Wellenberg et al., 2004). Investigations into this “outbreak” found that there was a clear temporal association of PMWS and PDNS; PDNS cases usually followed PMWS cases on the same farms. Studies have determined that the mean age of pigs affected by PMWS ranges from 6 to 14 weeks whereas the mean age of pigs affected by PDNS ranges from 12 to 16 weeks (Gresham et al., 2000). Similar observations were made in Korea and these authors speculated that the presence of both PMWS and PDNS in the same herd but in different age groups was probably due to different strains of PCV2 or varying susceptibility of the pigs (Choi et al., 2002). A recent case-control study investigating PDNS in the Netherlands found that there was a significant association of high antibody titers to PCV2 and the development of PDNS (Wellenberg et al., 2004).
The authors were not able to show PCV2-antigen by IHC in all of the PDNS cases but they were able to confirm the presence of PCV2 by PCR in all cases of PDNS. Importantly, the authors were able to show that porcine parvovirus or PRRSV nucleic acids were not present in many of the PDNS cases as determined by PCR (Wellenberg et al., 2004). A study comparing PCV2 serum load in PMWS and PDNS cases found that PDNS cases had significantly lower numbers of PCV2 in serum compared to healthy, subclinical PCV2-infected pigs (Olvera et al., 2004). This study further confirms that PDNS pigs are infected with PCV2. Mauch et al. (2004) observed abortions and death loss in dams after 94 gilts in mid-pregnancy and seronegative for PCV2-antibodies were transported to four PCV2 positive farms. Within 2 months of entry, 34 of the 94 gilts showed typical PDNS like lesions, 8 of 34 gilts aborted, and 4 of 34 gilts died. The gilts had necrotizing vasculitis in skin, renal cortex, lymph nodes, spleen ileum, and in the uterus wall (Mauch et al. 2004).
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Choi C, Chae C: Colocalization of porcine reproductive and respiratory syndrome virus and porcine circovirus 2 in porcine dermatitis and nephrology syndrome by double-labeling technique. Vet Pathol. 38:436-441, 2001
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Elbers AR, Hunneman WA, Vos JH, Zeeuwen AA, Peperkamp MT, van Exsel AC: Increase in PDNS diagnoses in the Netherlands. Vet Rec. 147:311, 2000
Gresham A, Giles N, Weaver J: PMWS and porcine dermatitis nephropathy syndrome in Great Britain. Vet Rec. 147:115, 2000
Lainson FA, Aitchison KD, Donachie W, Thomson JR: Typing of Pasteurella multocida isolated from pigs with and without porcine dermatitis and nephropathy syndrome. J Clin Microbiol. 40:588-593, 2002
Mauch C, Bilkei G: Porcine circovirus (PCV) associated losses in pregnant gilts. Pig J. 53:69-74, 2004
Olvera A, Sibila M, Calsamiglia M, Segalés J, Domingo M: Comparison of porcine circovirus type 2 load in serum quantified by a real time PCR in postweaning multisystemic wasting syndrome and porcine dermatitis and nephropathy syndrome naturally affected pigs. J Virol Methods. 117:75-80, 2004
Rosell C, Segalés J, Ramos-Vara JA, Folch JM, Rodríguez-Arrioja GM, Duran CO, Balasch M, Plana-Durán J, Domingo M: Identification of porcine circovirus in tissues of pigs with porcine dermatitis and nephropathy syndrome. Vet Rec. 146:40-43, 2000
Thibault S, Drolet R, Germain MC, D'Allaire S, Larochelle R, Magar R: Cutaneous and systemic necrotizing vasculitis in swine. Vet Pathol. 35:108-116, 1998
Thomson J, Smith B, Allan G, McNeilly F, McVicar C: PDNS, PMWS and porcine circovirus type 2 in Scotland. Porcine dermatitis and nephropathy syndrome. Post-weaning multisystemic wasting syndrome. Vet Rec. 146:651-652, 2000
Thomson JR, Higgins RJ, Smith WJ, Done SH: Porcine dermatitis and nephropathy syndrome. clinical and pathological features of cases in the United Kingdom (1993-1998). J Vet Med A Physiol Pathol Clin Med. 49:430-437, 2002
Wellenberg GJ, Stockhofe-Zurwieden N, De Jong MF, Boersma WJA, Elbers ARW: Excessive porcine circovirus type 2 antibody titres may trigger the development of porcine dermatitis and nephropathy syndrome: a case-control study. Vet Microbiol. 99:203-214, 2004