Swinepox: An Old Skin Disease That Still Matters in Modern Pig Farming

Swinepox is a visually striking but generally mild and self-limiting viral skin disease of pigs. It is caused by swinepox virus (SWPV), a poxvirus of the genus Suipoxvirus, and is mainly recognized in young pigs. The disease is characterized by a progression from erythematous macules and papules to vesicles or pustules, followed by necrosis, ulceration and dark crust formation. The pig louse, Haematopinus suis, is an important vector or mechanical transmitter, while skin trauma, other ectoparasites, direct contact and contaminated environments may facilitate spread. Histologically, epidermal hyperplasia, ballooning degeneration, vesicle or pustule formation, necrosis and characteristic eosinophilic intracytoplasmic inclusion bodies may be observed. Clinical appearance can strongly suggest swinepox, but PCR and histopathology are useful for confirmation, especially in unusual outbreaks. Differential diagnosis is particularly important when vesicular lesions are present because serious notifiable diseases must be excluded. Indian studies have documented SWPV outbreaks in several regions and have demonstrated a distinct Indian molecular lineage. Although mortality is usually low, outbreaks can cause production losses, secondary infections and increased management costs. Effective control depends mainly on ectoparasite control, sanitation, biosecurity, reduction of skin trauma and appropriate laboratory confirmation.