Exudative epidermitis (Greasy pig disease)
- Worldwide disease of pigs under 3 months of age caused by S. hyicus
- Highly contagious and persists in the environment for long periods
- S. hyicus produces exfoliative toxin that causes separation of cells in stratum spinosum resulting in rapid intraepidermal spread of organisms
- Similar to “scalded skin syndrome” in human neonates, due to skin infection by exfoliative toxin-producing Staphylococcus aureus
- Excessive sebacious secretion and exudation on surface of skin
- Pigs are anorexic, febrile, depressed and have a greasy, non-pruritic dermatitis
- SKin thickened, wrinkled and scaley
- Acute death in piglets under 3 weeks due to dehydration and septicaemia
- 20-100% morbidity; up to 90% mortality
- Organism enters skin via abrasions e.g. bite wounds
- Carried in vaginal mucosa and skin of sows
- Predisposed by lack of milk, weaning and other infections
- Piglets from non-immune sows are predisposed
- Passive transfer of antibodies from immune sows and development of immunity with age protect against disease
- Isolation from skin lesions
- Early systemic antibiotics amd topical antiseptics/antibiotics useful
- Disinfection after outbreak
- Wash sows before farrowing
- Differential diagnosis:
- Mange (Sarcoptes scabiei var. suis)
- Swine parakeratosis (zinc and essential fatty acid deficiency)
- Porcine juvenile pustular psoriasiform dermatitis (collarettes or rings typically on the ventrum of young pigs)
- Dermatosis vegetans (associated with a giant cell pneumonia)
- Dermatophytosis (most commonly Microsporum nanum)
Pathology
- = Exudative epidermitis of pigs
- Caused by Staphylococcus hyicus
- Affects neonatal piglets - often fatal, older piglets - milder disease
- Focal erosion of stratum corneum
- Brown exudate
- Dermatitis around eyes, ears, snout, chin and medial legs, may spread to ventral abdomen and thorax
- Rapidly becomes generalised -> greasy exudate over red skin -> hardened, cracked exudate
- In older piglets, milder localised disease develops around eyes, ears and face
- Grossly:
- Thickened epidermis, scaling
- Microscopically:
- Early - subcorneal pustular dermatitis extending to hair follicles -> superficial suppurative folliculitis
- Late - hyperplastic epidermis, thick keratin crusts with cocci, microabscesses