Erysipelas - Pig

Description

An infectious disease caused by Erysipelothrix rhusiopathiae. Affects mainly growing pigs causing septicaemia, [[Joints Inflammatory - Pathology#Arthritis|arthritis] and laminitis.

• Carrier pigs act as reservoir of infection
• Organisms excreted in faeces of acutely-affected pigs
• Ingestion of contaminated food and water, or via skin abrasions

History and Clinical signs

• Clinical outcome depends on susceptibility of pigs and virulence of strain
• Pigs susceptible after maternal antibody waned (after 3 months) and before protective immunity acquired (3 years)
• Change in diet, extremes of temperature and fatigue thought to predispose to infection
• Septicaemic form:
  • Acute; incubation period 2-3 days
  • Pigs found dead, febrile, depressed, recumbent or with stilted gait
  • Mortality high
  • Pregant sows abort
• Cutaneous form:
  • Diamond skin lesions
  • Fewer systemic signs, mortality rates lower
  • Pigs febrile with small, pink/purple raised areas or extensive diamond-shaped plaques over skin
  • Lesions may resolve within a week, or become necrotic and slough
• Arthritis:
  • Older pigs, chronic
  • Stiffness, lameness, non-weight bearing on affected limbs
  • Joint lesions with erosion of articular cartilage, fibrosis and ankylosis
  • Strong impact on productivity
• Chronic valvular endocarditis:
  • Vegetatic thrombosis of mitral valves
  • Asymptomatic or congestive heart failure and sudden death with stress
• Diagnosis:
  • Diamond-shaped skin lesions
  • Haematology and post mortem, especially liver, spleen, heart valves, synovial tissues
  • Slender Gram-positive rods on microscopy of acute lesions; filamentous forms in chronic lesions and smears
  • No growth on MacConkey agar
  • Colonial characteristics and biochemical tests

Treatment

• • Penicillin and tetracyclines for acute infections
  • Hyperimmune serum
• Control:
  • Hygience
  • Cull chronic cases
  • Isolate affected pigs
  • Live attenuated or inactivated vaccines

• • Most important and most common cause of arthritis
  • Causes chronic serofibrinous polyarthritis
  • Also causes discospondylitis
    • Similar to discospondylitis in dogs
  • Thickening of synovial membrane lining + plus hyperaemia and villus formation + lymphocyte and plasma cell infiltration
  • Acute stage
    • Increased joint fluid + hot swollen joints
    • Also expresses as septicaemic and urticarial lesion on the back (diamond shaped)
    • May involve endocarditis as a sequel
  • Chronic stage
    • More commonly encountered
    • Erosion of articular surface of joints with formation of pannus +/- joint ankylosis
    • Vaccination prevents septicaemic and urticarial forms but has no effect on joints
      • Probably due to dead bacteria still stimulating host immune system
  • Septicaemia lo9calises in meninges and joints
  • Well known in piglets in their first two months of life
  • Expresses as acute fibrinopurulent arthritis