Bacillary Necrosis

  • Fusobacterium necrophorum
  • calves and lambs
  • common in intensively reared beef cattle
  • occurs following an infected umbilicus in neonates and from rumenitis in adult cattle
Gross
  • rounded pale multiple foci of coagulative necrosis throughout the liver
  • unsoftened, greyish-yellow patches
  • ringed by a zone of hyperaemia
  • foci coalesce in severe cases
  • in adult animals, these lesions may have progressed to abscesses following lysis of the coagulated necrotic tissue and the formation of fibrous capsule around the damaged tissue
  • if animal survives, these lesions may soften develop into abscesses
Microscopically
  • coagulative necrosis
  • possible evidence of migrating flukes
  • bacteria can be demonstrated in the periphery of the necrotic tissue, especially near its junction with viable tissue
  • there is a rim of neutrophilic cells