Special Veterinary Pathology

Braxy / Bradshot and black disease

BRAXY

Synonym : Bradsot

Definition

• Acute infectious fatal disease of sheep caused by the absorption of toxins produced by Clostridium septicum and produced hemorrhagic abomasitis

Aetiology

• Clostridium septicum

Incidence

• The disease is mainly seen in Scotland and Scandinavia
• Canada and Northern United State

Transmission

• Ingestion of frozen grass or other feed

Pathogenesis

• Organisms enter through the wounds on the wall of abomasum caused by nematodes and chilled grass in winter liberates toxin and cause the lesions

Clinical signs

• Colic, abomasal bloat, coma and death within few hours

Gross lesions

• Thickening of wall of abomasum,oedema and haemorrhages
• Intestine – the same lesions similar to abomasum

Microscopic lesions

• Large bacilli can be seen in tissue section

Diagnosis

• Demonstration of causative bacilli in tissue sections
• Bacilli in tissue sections

BLACK DISEASE

Synonym : Infectous necrotic hepatitis

Definition

• It is an acute fatal infection of sheep and rarely cattle caused by Cl. novyi type B

Aetiology

• Cl. novyi type B

Incidence

• First reported in Australia and subsequently in New Zealand and many other countries of the world including India

Transmission

• Ingestion
• Faecal contamination of the pastures by carrier animals is the important source of infection

Pathogenesis

• The organisms reach the liver from the intestine and anaerobic environment produced by migration of liver flukes activates the bacteria which release exotoxin casing hepatic necrosis

Clinical signs

• Animals die within a few hours and so no symptoms may be seen

Gross and microscopic lesions

• Multiple foci of necrosis in liver, petechiae on the epicardium and endocardium and hydropericardium
• Subcutaneous venous congestion causes dark discolouration of the skin and hence the name black disease

Diagnosis

• Pathological findings and isolation of the organisms