The lungs are usually rubbery and mottled. It appears that most infections are subclinical. It is not known why some infections result in clinical manifestation of the syndrome. The diagnosis of PMWS is based on the age of affected pigs, typical wasting appearance, and necropsy lesions. Microscopic and imunohistochemical examination of tissues reveals unique lung and lymphoid tissue lesions with the presence of PCV-2.
Differential diagnosis includes other conditions that can cause wasting in pigs.
These include infectious diseases like PRRS, swine influenza, illeitis, and enzootic pneumonia. There are also some noninfectious causes of wasting in pigs that should be ruled out such as failure to adjust to solid diets, and a variety of management factors such as high stocking densities and continual production. Treatment and Prevention Antibacterial medication is usually ineffective and there are no vaccines available. Pigs are reported to respond well to injections of corticosteroids , with improved growth rates and reduced mortality. Prevention of the syndrome is based on biosecurity precautions and good husbandry practices.