NAVLE Musculoskeletal

Bovine Actinomycosis Study Guide

Actinomycosis, commonly known as "lumpy jaw" or "big jaw", is a chronic, progressive, pyogranulomatous infection primarily affecting the bony tissues of the head in cattle.

Overview and Clinical Importance

Actinomycosis, commonly known as "lumpy jaw" or "big jaw", is a chronic, progressive, pyogranulomatous infection primarily affecting the bony tissues of the head in cattle. The disease is caused by Actinomyces bovis, a gram-positive, anaerobic, filamentous bacterium that is part of the normal oral microbiota of ruminants. This condition represents a significant cause of economic loss in cattle production due to reduced feed intake, weight loss, and condemnation at slaughter.

The disease was first described by Bollinger and Harz in 1877 and remains an important differential diagnosis for facial swellings in cattle. Understanding actinomycosis is essential for NAVLE preparation as it tests knowledge of infectious disease pathophysiology, diagnostic approach, and treatment protocols in food animal medicine.

Characteristic Description
Gram Stain Gram-positive
Morphology Filamentous, branching rods (less than 1 micrometer diameter)
Oxygen Requirement Anaerobic to microaerophilic
Acid-Fast Staining Non-acid-fast (distinguishes from Nocardia)
Normal Habitat Oral cavity, nasopharynx, and GI tract of healthy ruminants
Environmental Survival Does not survive outside host tissues

Etiology

Causative Agent

Actinomyces bovis is the primary causative agent of bovine actinomycosis. Key microbiological characteristics include:

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