[C] 1.39 Gangrene

Question 1

Summarise gangrene

Answer 1

Secondary phenomenon after necrosis

• Gangraena sicca
• Gangraena humida
• Gas-gangrene

Question 2

Gangraena sicca

Answer 2

No bacteria

• Physiologic (Umbilical cord)
• Desiccation following necrosis
  
  • Macroscopic changes:
    
    • Shrunken
    • Dark brown
    • Hard as wood
    • Histopathology: Recognisable tissue structure
  • Skin
    
    • Chronic erysipelas
  • Foetus:
    
    • Mummification

Question 3

Gangrena humida

Answer 3

Necrotised area superinfected with saprophytic bacteria (proteolysis)

• Bacterial infection
• Appearance
  
  • Pulpy & soft
  • Grey-black (H₂S + Hb
  • Putrid smell
  • Gases

Question 4

Gas-gangrene

Answer 4

• Clostridia
• Muscles
• Gas-oedema

Question 5

Gangrena humida: Occurance

Answer 5

• Oral cavity
• Lungs
• Uterus

Question 6

Gangrena humida: Specific diseases

Answer 6

• Blackleg-disease
• Malignant oedema (skin & muscles)

Question 7

Gangrena emphysematosia

Answer 7

• Blackleg disease
• Malignant oedema
• Agents (Clostridium)
  
  • C. chauvoei
  • C. septicum
  • C. histolyticum
• Produce exotoxin, CO₂ & acid
• Effect of acids & exotoxin:
  
  • Muscle necrosis
  • Increased vascular wall permeability

Question 8

Gas gangrene

Answer 8

General effect of exotoxin

• Autointoxication
• Skeletal muscle: Myositis emphysematosa
• Stomach wall:
  
  • Swine: Gastritis emphyematosa
  • Lamb: Bradsot
• Liver: Hepatitis emphysematosa
  
  • Sheep: Infectious necrotic hepatitis
• Uterus: Metritis emphysematosa