Introduction

• Cause:
  • Clostridial myositis in cattle presents as blackleg or malignant edema.
  • Cl chauvoei is responsible for causing Blackleg in cattle.
  • Cl chauvoei, cl. novyi, cl. Septicum and/or cl. Sordelli are responsible for malignant edema.
• Signs:
  • Blackleg:
    • Acute death is the most common clinical finding .
    • If seen early in the disease process sudden onset depression, pyrexia and initial stiffness progressing to lameness and recumbency.
    • Death follows shortly after the onset of the clinical syndrome.
  • Malignant edema:
    • Acute painful swelling and pronounced edema of muscle group or vagina/vulva.
    • Acute death.
• Diagnosis: fluorescent antibody tests on slides from the primary lesion.
• Treatment:
  • 25,000-40,000 IU Procaine Penicillin per kg body weight has been advocated.
  • Non-steroidal anti-inflammatories.
  • Intra-venous fluid therapy.
• Prognosis: poor.

Pathogenesis

Etiology

• Clostridia Clostridium spp are Gram positive, spore bearing anerobic bacteria.
• They are ubiquitous in the environment and are widely dispersed in soil and vegetative matter, whilst also serving as a commensal within the intestines of many ruminant species.
• Blackleg:
  • Ingestion of spores allows bacteremic spread to the viscera and muscle tissue where they may lie dormant for a prolonged period of time, before a trigger factor initiates the onset of clinical disease.
• Malignant edema:
  • Mixed clostridial infection normally occurs in association with a deep penetrating wound which favours anerobic conditions for replication or infection of the vulva/vagina in association with dystocia.
  • Rapid multiplication of clostridial spores within the damaged tissues causes release of its associated toxin causes vast tissue damage, often necrotizing and hemorrhagic in nature.

Predisposing factors

General

• Blackleg: ingestion of soil or vegetative matter containing Cl. Chauvoei spores by cattle at pasture, or through soil contamination or spoilage of conserved forages.
• Malignant edema: a deep penetrating wound favouring anaerobic conditions for clostridial replication or dystocia associated injury, allowing bacterial infection.
• Blackleg and Malignant edema: poor hygiene associate with injection site and technique.

Specific

• Ingestion of Clostridiam chauvoei spores.
• Trigger factors which reduce oxygen tension or trauma to tissues, which may include muscle bruising (such as the result of a kick), injection site reactions and dystocia.
• Tooth eruption during time of spore ingestion, allowing systemic spread to peripheral sites. Tooth eruption
• Deep penetrating wounds allowing bacterial entry and replication under anerobic conditions.

Timecourse

• Hours.

Epidemiology

• Normally sporadic in nature, with a small number of animals affected in any at risk population.
• However, in the case of Blackleg, soil or vegetative contamination of conserved forages and their subsequent feeding may result in epizootic episodes.

Diagnosis

Treatment

Prevention

Outcomes