Necrobacillosis Ahmed Sobhi Muhammad Eslam Muhammad Sayyed Definition

Necrobacillosis Ahmed Sobhi Muhammad Eslam Muhammad Sayyed

Definition • Necrobacillosis is a disease of different species of animal (horsecattle- sheep- goat) and human. • Characterized by septicemia, necrosis and damage for different tissues the body , also it is a fatal disease in young animals.

Different conditions caused by the same micro organism 1) 2) 3) 4) Equine thrush Liver necrosis Calf diphtheria Footrot

1 - Necrotizing pododermatitis (equine thrush) • Necrotizing pododermatitis is a painful necrotizing condition of the frog central and the lateral sulci if the hoof. • Wet humid conditions allow for softening of the frog and bacterial colonization. • F. necrophrum produces leukotoxin as the major virulence factor.

Grossly lesions consist of softening the frog with black discoloration and very foul odor. Microscopically the lesions are characterized by necrosis and suppurative inflammation of the frog epithelium and sometimes deeper tissues.

2 - Hepatic necrobacillosis

Pathogenesis Hepatic necrobacillosis liver abscess is a secondary infection of ruminal wall which called (ruminal-liver abscess complex) where rapid fermentation of grains by M. O occurs, causes damage for protective surface of rumen so occurs invasion and spread in blood stream so reaches to portal circulation causing liver abscessiation by leukotoxin mediated cytotoxicity

Grossly • The ruminal lesions are characterized by a marked inflammatory reaction and necrosis. • Hepatic abscesses which are pale yellow and spherical with irregular outlines.

Microscopically Coagulative necrosis of the hepatocytes with a surrounding intense zone of hyperemia and inflammation which becomes thickened later by thick capsule of granulation tissue.

3 - Footrot

4 - Calf diphtheria

References • Jubb, Kennedy & Palmer's Pathology of Domestic Animals. 5 th ed. • Carlton L. Gyles, John F. Prescott, J. Glenn Songer, Charles O. Thoen. Pathogenesis of Bacterial Infections in Animals. 4 th ed. • The Merck Veterinary Manual, www. merckvetmanual. com