- Cause of epizootic pneumonia in cattle known as Shipping Fever, Transit Fever or pneumonic pasteurellosis (90% caused by Mannheimia haemolytica Biotype A, serotype 1 but also Pasteurella multocida
- Usually secondary to viral infections such as parainfluenza - 3 or IBR, bacterial infections such as Mycoplasma or environmental stress
- May contribute to Enzootic pneumonia of calves, Enzootic pneumonia of lambs
- Enzootic pneumonia in sheep
- Peritonitis in sheep
- Permeability types of pulmonary oedema
- Septicaemia in young lambs
- Causes gangrenous mastitis in sheep
- Beta-haemolytic on blood agar
- Grow weakly on MacConkey agar
- Odourless
- All are Mannheimia A biotypes (previously Pasterurella haemolytica)
- Strains often produce a cytotoxin, known as leukotoxin, which kills leukocytes of ruminants
- Leukotoxin is a member of the RTX group toxins, and is probably largely responsible for the pathogenicity of the bacteria in septicaemia and pneumonia