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PMWS and PDNS in the UK

by 5m Editor
5 June 2007, at 2:03pm

UK - Veterinary Laboratories Agency (VLA) Quarterly Surveillance report on PMWS and PDNS from January to March 2006.

Diagnoses of PMWS (as a percentage of relevant diagnostic submissions) levelled out during the quarter compared with the same quarter last year for the first time since 2002 (see histogram). Occasional examples of wasted pigs with severe typical lymph node pathology continue to be presented. There is also a push by some vets to reconfirm the presence of PMWS on units to justify PCV 2 vaccination programs. Complicated cases involving multiple pathogens also continue to be presented.


% of submissions diagnosed with PDNS

In one breeder unit producing store pigs three live weaner-growers of 6, 9 and 11 weeks were submitted following feedback reports that clinical signs of PMWS were being recorded in older grower pigs from this source; some clinical signs had also been seen on this unit. A persistent cough starting in the farrowing house was also present. Pigs are reported to be enzootic pneumonia free and sows are vaccinated with live PRRS-vaccine 2w post-farrowing.

Vaccination of suckling piglets with a combined H. parasuis (serotypes 4 &5) and Mycoplasma hyopneumoniae vaccine had recently been instigated. The two older pigs were ill-thrifty hairy and dyspnoeic when moved, with ecchymotic haemorrhages present on the ear tips. Gross findings included generalised lymphadenomegaly including prominent inguinal lymph nodes (lymph nodes were white with a homogeneous texture). There was pneumonia in one pig from which Pasteurella multocida, Streptococcus suis (untypeable) and PRRS virus were isolated). Histopathology confirmed chronic proliferative bronchointerstitial pneumonia as well as widespread lymphoid necrosis and aggregates of epithelioid macrophages. These findings confirm PMWS and were unexpected as this herd was incorporating Hampshire breeding into its lines, instead of Large White a measure generally regarded as a successful policy in countering PMWS.


% of submissions diagnosed with PDNS

Diagnostic rates for PDNS remain similarly low this quarter, although Carmarthen received their first case. Mortality rates in affected groups can be high with one case reporting a 35% mortality from 1000 pigs on an all in all out finishing unit. In another case ataxia was reported as one of the presenting signs where three died from a pen of 20 on a unit with 590 18 week old finishing pigs.

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