Skin Lesions and Diseases

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Name Etiology Signs - Lesions Comments
Actinobacillus suis infection Actinobacillus suis Unusual but in feeding/finishing and mature swine, the lesions are raised, red and rhomboid. Signs, internal and cutaneous lesions can (rarely) resemble those of acute erysipelas
Aural hematoma Trauma to ear followed by hemorrhage between skin and cartilage Thickening and inflammation of ear over organizing hematoma. Lesions can be very large. Trauma from many causes: bites, violent head shaking, commingling.
Dermatosis vegetans Semi-lethal hereditary defect affecting occasional pigs. Coronary band lesion on one or more feet of neonate, which leads to hoof deformity. Red macules expand, become papillomatous. Defect originally in Landrace breed. Most affected piglets die within a few weeks. Many survivors have interstitial pneumonia.
Epitheliogenesis imperfecta Congenital defect Missing areas of skin since birth, often over back or rump, perhaps mouth. Small lesions often heal by scarring.


Erysipelothrix rhusiopathiae  Acute: Raised, rhomboid lesions. 
Chronic: Peeling plaques often over back. Necrosis of parts of ears, tail.
Acute skin lesions often resolve if animal recovers promptly. Skin lesions appear slightly after acute febrile stage of disease.
Greasy pig disease  Staphylococcus hyicus skin infection Brownish lesions in axilla and groin spread to head, face, other areas, perhaps mouth. Lesions dark, greasy, often extensive. Triggering factors are poorly understood. Irritation of skin may precede the infection. Treatment seldom is satisfactory.
Necrotic ear syndrome Trauma, vasculitis, often bites, and secondary infection. Areas of ulceration, infection and necrosis in ear(s). Infection occasionally results in septicemia and death.
Pediculosis (lice) Haematopinus suis louse. Rubbing, scratching, anemia. Eggs attached to hair on jowls, flanks, inner surface of legs, behind ears. Leads to unthriftiness and anemia. Lice sometimes transmit pox virus.
Photodynamic dermatitis Photodynamic agents (plants or drugs) plus sunlight. White areas of skin inflamed and pruritic. Severe peeling of areas of necrotic skin. Many plants and drugs are photodynamic. Conjunctivitis often accompanies the dermatitis.
Pityriasis rosea Unknown but some evidence of hereditary predisposition. Raised, expanding circular lesions in 12-14 week old pigs. Lesions usually on ventral abdomen, less often elsewhere. Lesions resolve within a few weeks without treatment. Disease may go unnoticed unless ventrum is examined.
Porcine dermatopathy and nephropathy syndrome (PDNS) Mechanism unknown but associated with post-viral (PCV2, PRRSV, CSF)* infection, perhaps an immune mediated disease Red to purple, circular 1 cm lesions appear on perineal, ham, ventral regions that may enlarge and coalesce. Nephropathy also present may lead to death in days to weeks. Diagnosis by recognition and histopathology on skin and kidney. Usually sporadic but morbidity can approach 10%. No treatment.
Pox Swine pox virus Initial 1-2 cm round to oval lesions on ventrum but can extend over the body. Papule, vesicle, pustule and scab stages. All age groups susceptible. Usually seen in young, growing pigs. Pox virus sometimes transmitted by lice. Congenital pox occurs sporadically.
Pustular dermatitis Lancefield type C Streptococci Pustules on posterioventral abdomen, inguinal area, inner thighs, perhaps eyes, lips, ears. Pustules rupture, are replaced by black scabs. Most pigs recover in a few weeks. Provide clean bedding, improve sanitation. Recovery perhaps hastened by antibiotics in water or feed.
Ringworm Usually Microsporum nanumor Trichophyton verrucosum. Roughly circular, expanding hairless areas that develop crested scabs. Non-pruritic. Usually self-limiting. Contagious to humans. Occasionally caused by other fungi. Usually seen in old swine and quite common in sows.
Skin necrosis of piglets Skin abrasion with secondary infection. Abrasive lesions on knees, fetlocks, coronets, hocks, or elbows lead to septicemia; often high mortality. Lesions often are more serious than realized. Less abrasive surfaces or adequate bedding are necessities.
Sunburn Excessive sunshine on skin Pigs may “drop to belly” from pain on sunburned back. Reddening, thickening, peeling of most exposed skin, usually on back and ears. Unpigmented skin more susceptible. If shade is provided, pigs will not lay in the sun.
Vesiculating viral diseases Foot-and-mouth disease (FMD), Vesicular stomatitis (VS), Vesicular exanthema(VE). Round to oval vesicles on feet, in and around the mouth, on snout, in nostrils, occasionally elsewhere. Lesions similar in all vesiculating viral diseases and cannot be used to differentiate. Report all promptly!
Vices Tail or flank biting; savaging of moribund swine. Tail or flank bite wounds. Moribund swine often have red, linear bite marks. Overcrowding and idleness are thought to contribute to development of vices.

CSF - classical swine fever
PCV2 - porcine circovirus type 2
PRRSV - porcine reproductive and respiratory syndrome virus