PCVAD and PDNS in the UK

There was a continuation in the steady downward trend in the proportion of diagnostic submissions for which a diagnosis of postweaning multisystemic wasting disease (PMWS) or porcine circovirus type 2 (PCV2)-associated disease was established.

This resulted in a statistically significant lower percentage than in any year other than 2005 or in 2000 – the first year the diagnosis was recorded in the first quarter. The first British confirmed diagnosis of PMWS was in the third quarter of 1999.

Cases continued to occur in much older pigs (15 to 20 weeks) with several Regional Laboratories (RLs) recording incidents associated with descriptions of ‘sudden death’ in finishing pigs. A handful of cases still continued to occur in the classical age range of 6 to 8 weeks of age, and a further case of circoviral hepatitis was also recorded with a typical presentation of jaundice and death in 3 to 4-week-old Gloucester Old Spot pigs. Possibly the first diagnosis of PMWS in other than Sus scrofa was made in a 6-month-old red river hog (Potomochoerus porcus). Although the numbers of PMWS cases occurring in non-domesticated breeds and species are very few, they usually occur in much older animals.

The percentage of diagnosable submissions of PDNS peaked in the first quarter of both 2000 and in 2005 but fell during 2006 similar to those obtained in the intervening years. The reason for this finding is not known. A surprise was the lower than expected number of PDNS cases associated with finisher mortality. This may not reflect the true situation as it is easy to avoid selecting PDNS cases with skin lesions for a differential diagnostic necropsy on the presumption that the clinical diagnosis is sufficient. However, other diseases commonly occur in PDNS cases.

One notable PDNS case in a Gloucester Old Spot pig presented with malaise and ulcerative sloughing mouth lesions. Foot and mouth disease and Aujeszky’s disease (PRV) were among the possible diseases initially considered because of the presence of tonsillar necrosis. However, they were ruled out on the basis of the full clinical history available. Uremia, resulting from chronic PDNS-associated renal failure, was considered the probable cause of the ulcerative mucosal lesions.