Diagnosis of PMWS


In the absence of a clear causal agent, there are four aspect that lead to an accurate diagnosis:

Clinical signs exhibited by the group of pigs

The pathological signs exhibited by the group of pigs

The herd history over 3 months

The epidemiological history of the infected area.


Clinical signs exhibited by the group of pigs

The course of the condition can make definitive diagnosis difficult, initially.  The major clinical signs are variable, depending largely on the secondary pathogens present on the unit.  However, there are prime clinical signs:

The nursery pigs do well until 30-40 lbs.  Several producers actually comment that the pigs have never looked better.

As the condition starts, many producers note that 120-160 lb pigs start developing an ‘ileitis’ which does not respond to treatment – either by vaccination or antimicrobial therapy.

Some producers have commented on an increase in coughing in the farrowing house.

A couple of pigs 60 lbs or more develop Porcine Dermatitis and Nephropathy Syndrome (PDNS).  This is often dramatic with several pigs in a pen being affected.  Sporadic (rare) PDNS is normal.

Increasing numbers of growing pigs suddenly loose their body condition.  The pigs loose weight rapidly, some within 4 days.  The pigs are generally of 30 lbs to 160 lbs bodyweight.  The condition appears in a few pigs each day; these either die or are moved into the hospital pens.  Males tend to be more affected than females and there is generally a litter effect.

The farm now has full blown PMWS

There is an increase in respiratory diseases in pigs less than 60 lbs or an increase in digestive diseases in pigs older than 60 lbs – this largely depends on the prevalent conditions on the farm

One characteristic of PMWS is that some pigs in the pen look normal whereas other are extremely emaciated.



The farm experiences a general increase in severity and frequency of secondary pathogens and their clinical signs.  Diseases which have not been seen for several years reappear.

Glässer’s disease



Greasy pig disease







Clinical findings



Gross pathological findings



Laboratory findings

Herd History



Treatment and control

PMWS negative

PMWS positive