BLACK QUARTER (BLACKLEG)

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Causative Agent(s)

Clostridium chauvoei: a gram-positive spore forming, rod shaped bacterium. Occasionally

Clostridium novyi and Clostridium septicum are isolated (false black leg).

 

Clinical Presentation and Epidemiology

In cattle, if seen before death, there is severe lameness with pronounced swelling of the upper part of the affected leg. There may be pyrexia, depression, and anorexia. In the early stages the swelling is hot and painful to touch but soon becomes cold and painless, and oedema and emphysema can be felt (palpable crackle/crepitation). The skin is discoloured and soon becomes dry and cracked. Lesions are usually confined to the upper part of one limb, and occasionally at the base of tongue, heart muscle, diaphragm, psoas muscle, the brisket, and the udder. The condition develops rapidly, and the animal dies within 12-36hrs, sometimes up to 10days after appearance of clinical signs. In sheep, there is stiff gait and disinclination to move. Subcutaneous oedema is not common and gaseous crepitation cannot be felt before death. Discolouration of the skin may be evident, but necrosis and gangrene do not occur. When infection occurs through wound, extensive local lesion is seen.

Diagnostic Considerations

Bacteriological examinations which include bacterial culture and sensitivity tests of the exudates from affected portions. This will reveal cigar shaped rods.

Management and Treatment
  • Dressing of affected lesions with local injection of
  • Systemic antibiotic: Penicillin in large dose, gentamicin, neomycin, oxytetracycline or

NB: Treatment is usually ineffective in an advanced septicaemic stage. Antibiotic therapy has been found to be effective when administered within 12 hours of the appearance of clinical symptoms.

  • Crystalline penicillin (20,000 – 25,0000 IU/kg) IV on day one followed by penicillin G procaine (17,000 – 25,000 IU/kg) IM x 4/7
  • Penicillin G sodium: 10,000-20,000 IU (6-12 mg)/kg IV or IM, q6-8h x5/7
  • Penicillin G procaine: 17,000-25,000 IU (10-15mg)/kg IM or SC, q12-24h x5/7
  • Oxytetracyline LA 20mg/kg IM (repeat after 2-4 days)
  • Gentamicin 5 mg/kg IM q8h x 3-5/7

Control measure is by the administration of a multivalent vaccine containing Clostridium chauvoei, C septicum, and where needed, C novyi