Malignant Edema:

• It is also known as gas gangrene.
• It is an acute fatal toxemia of sheep, goat, cattle, horse, swine
• It is characterized by fever, edematous and emphysematous swelling around the wound.

Etiology:

• Clostridium septicum is main causative agent.
• Beside these, other species of clostridium also causes this disease.
• It is anerobic gram-positive spore forming rod shaped organism measuring 0.4-0.6 µ in width and 2-6µ in length.
• Organism produces two types of toxins, i.e. α and β toxin. Hyaluronidase and collagenase are also produced by the organisms.

Epidemiology:

• Disease is distributed throughout the world.
• These diseases are prevalent in areas where soil is contaminated with bacterial spores.
• They are especially found in warm, humid climates.
• Young, well-fed animals (6 months to 2 years) are most susceptible due to high muscle activity and minor trauma risks.
• High case fatality rate (often >80%) if untreated.

Mode of Transmission:

• Organisms are common inhabitants of alimentary tract.
• Through contaminated soil
• Through surgical or accidental wounds
• Castration, docking, parturition injuries
• Abrasion and puncture wound

Pathogenesis:

Clinical Signs:

• Incubation period: 12-48 hours
• Edematous swelling involving subcutaneous tissue leading to edema in initial stage.
• Hyperemia of conjunctival mucosa and signs of toxemia
• Foul smelling discharge through wound
• Swelled area becomes cold later.
• Gas formation cause wound to break with oozing of serosanguineous materials.
• Swelling sometimes located in head and inter-mandibular space.
• Stiffness, muscle tremor and lameness
• Death usually occurs within 24-48 hours due to toxemia.

PM Lesion:

• Edematous and emphysematous swelling
• Gangrene of affected tissues
• Gelatinous blood-stained fluid is observed in wound.
• Blood tinged fluid in peritoneal, pericardial and pleural sac.

Diagnosis:

• Based on history of injury and wound
• Based on clinical signs.
• FAT
• Isolation of organism
• Animal inoculation test: 1 ml of infected sample inoculated in guinea pig. Death occurs within 48 hours.

Differential Diagnosis:

• Disease should be differentiated with black quarter. In black quarter there is deep muscle involvement and muscle becomes necrotic.

Treatment:

• Massive dose of crystalline penicillin through IV route followed by procaine penicillin through IM route will be rational approach.
• Penicillin @10,000 IU/kg, b.wt., BID for 3-5 days
• Tetracycline may also be used. Dose rate: 1ml/10 kg, b.wt. IM repeated after 72 hours.
• Avil or Cural @10-15 ml, IM on alternate days
• Surgical incision and drainage of wound; Irrigation with 1% H₂O­₂
• Fluid therapy: Rintose, Dextrose

Control Measures:

• Proper cleanliness and hygienic measures will reduce the chance of infection.
• Both surgical and accidental wounds should be properly treated.
• Area of contamination should be adequately disinfected.
• Dead carcasses should be disposed off properly. They should be burnt or buried and soaked with lime.
• Vaccination should be done as a routine measure in enzootic area.