EVOLUTION

ANIMAL BREEDS

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BEHAVIOUR

EXOTIC ANIMALS

SPECIAL SECTION

Bacterial Disease - Malignant Edema

Introduction:

Malignant edema is an acute, generally fatal toxemia of cattle, horses, sheep, goats, and pigs usually caused by Clostridium septicum, often accompanied by other clostridial species. Other clostridia implicated in wound infections include C.chauvoei, C.perfrigens, C.novyi and C.sordellii. The disease occurs worldwide. A similar infection in man is not uncommon.

Etiology

Clostridium septicum is found in soil and intestinal contents of animals (including man) throughout the world. Infection ordinarily occurs throught contamination of wounds containing devitalized tissue, soil, or some other tissue-debilitant. Wounds caused by accident, castration, docking, insanitary vaccination, and parturition may become infected.

Clinical Findings and Diagnosis

General signs, such as anorexia, intoxication and high fever, as well as local lesions, develop with few hours to a few days after predisposing injury. The local lesions are soft swellings that pit on pressure and extend rapidly because of the formation of large quantities of exudates that infiltrates the subcutaneous and intramuscular connective tissue of the exudates that infiltrates the subcutaneous and intramuscular connective tissue of the affected areas. The muscle in such areas is dark brown to black. Accumulations of gas are uncommon. Severe edema of the head of rams occurs after infection of wounds inflicted by fighting.

Malignant edema associated with lacerations of the vulva at parturition is characterized by marked edema of the vulva, severe toxemia, and death in 24-48 hour. Similarity to blackleg is marked, and differentiation made on necropsy is unreliable; laboratory confirmation is the only certain procedures. Horses and pigs are susceptible to malignant edema but not to blackleg.

Braxy

This disease seems to be confined mostly to European sheep fed on "frosted" pasture.

Diagnosis

It can be confirmed rapidly on the basis of fluorescent antibody staining of Clostridium septicum from a tissue smear. However, Clostridium septicum is an extremely active postmortem invader from the intestine, and its presence in a specimen taken from an animal that has been dead for ≥24 hour is not significant.

Control

Bacterins are used for immunization. Clostridium septicum usually is combined with C.chauvoei in a blackleg/malignant edema vaccine and is available in multicomponent vaccines. In endemic areas, animals should be vaccinated before they are castrated, dehorned or docked. Calves should be vaccinated at 2 months of age.

Two doses 2-3 week apart generally give protection. In high-risk areas, annual vaccination is indicated, as is revaccination after severe trauma.

Treatment with high doses of penicillin or broad-spectrum antibiotics is indicated early in the disease. Although injection of penicillin directly into the periphery of the lesion may minimize spread of the lesion, usually the affected tissues still slough.


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