Description
An infectious disease caused by Erysipelothrix rhusiopathiae. The disease is characterised by sudden death, septicaemia, [[Joints Inflammatory - Pathology#Arthritis|arthritis], endocarditis, diamond shaped skin lesions, laminitis and abortion in pregnant sows. Carrier pigs act as reservoir of infection and Organisms are excreted in faeces of acutely-affected pig. Infection occurs via ingestion of contaminated food and water, or through skin abrasions.
Signalment
May occur in certain conditions often during hot humid weather or in particular buildings or fields.
Diagnosis
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