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
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Last modified: Tuesday, 20 March 2012, 7:03 AM