Black Quarter

BLACK QUARTER

Synonym: Black leg, quarter ill, Symptomatic anthrax

Definition

  • Acute febrile disease of cattle (6 month to 2 years), less often of  sheep, goat and swine characterized by emphysematous, sero haemorrhagic swelling in the heavy muscles, especially of the hind limbs caused by Clostridium chauvoei

Etiology

  • Clostridium chauvoei - Gram positive, spore forming, rod shaped bacterium

Incidence

  • The disease is enzootic in particular areas of India and the mortality rate may approach 100%

Transmission

  • Infection is ingestion of spores
  • In sheep: wound infection

Pathogenesis

  • Incubation period: 1- 5 days
  • Infection is by ingestion and the organisms multiply in the intestine and through blood stream reach the muscle (thigh, shoulder)
  • Necrosis of muscle with formation of gas (Necrotizing Myositis) -Gangrene
  • Smell of Rancid butter(Ferments sugars by organisms) 
  • Death within 24 hrs to 60 hrs. Death may be due to toxaemia

Clinical signs

  • Fever, lameness, visible swelling of muscles- Tongue, diaphragm, myocardium and gluteal muscles
  • In early stages, the swelling is hot and painful to the touch but soon cold and painless and oedema and emphysema can be felt

Gross lesions

  • Crepitating swelling of the muscle(extremities)
  • Rubber sponge and dark brown or black sero sanguineous fluid exudes with gas bubbles -Gas gangrene
  • Affected muscles appears black due to the formation of iron sulphide from H2S and iron of blood
  • Muscle – Centre area is dry and have odour of rancid butter
  • Regional lymph nodes – Swollen and oedematous
  • Large muscles – Diaphragm and tongue
  • Internal organs – Heart, lung, kidneys, liver, spleen and intestine showed acute congestion

Microscopic lesions

  • Muscle fibres separated and showed waxy degeneration and coagulation necrosis
  • Streaks of haemorrhages - Collection of neutrophils, lymphocytes and Gram positive organisms demonstrated in tissue sections

Diagnosis

  • May be confirmed by gross lesions
  • Demonstration of organism – from the fluid incised swelling
  • Biological tests using guinea pigs
  • Fluorescent Antibody Technique (FAT)
  • Fatal course and found dead before signs of illness are seen
Last modified: Tuesday, 20 March 2012, 7:03 AM