• Cause: disease process associated with a filamentous gram-positive, anaerobic or microaerophilic bacilli of the genus Actinomyces, phylum Actinobacteria.
• Signs: can range from non-specific findings such as lethargy and anorexia to visible masses, ulcer and/or sinus tracts that are most reported around the face and jaw. Dyspnea and tachypnea may be noted in animals with pulmonary and/or pleural disease associated with actinomycosis.
• Diagnosis: bacteriologic identification of filamentous bacilli together with the presence of sulfur granules within affected tissue(s), or positive identification using molecular methods.
• Treatment: Actinomyces spp are typically sensitive to penicillin, amoxicillin, clindamycin and doxycycline. Treatment with high doses for a prolonged period is usually required. Other treatment modalities may be required depending on the location of infection and body system(s) affected.
• Prognosis: good to fair if disease is recognized early and followed by prompt and appropriate treatment(s); guarded to poor if infection is in a critical location or if disease is identified in later stages with significant tissue destruction and/or multiple sinus tract formation.

Presenting signs

• May be non-specific such as lethargy and anorexia.
• Specific signs depend on site(s) affected:
  • Visible and/or palpable mass(es), ulcers and/or sinus tracts. Most commonly reported around the face and jaw.
  • Dyspnea, tachypnea may be reported in animals with thoracic disease.

Acute presentation

• Presenting signs as above, although sudden death has been reported in a ferret with pulmonary lesions attributed to actinomycosis.
• Acute presentation may be limited to lethargy and anorexia only.

Geographic incidence

• No known geographic association has been established.

Age predisposition

• No known age predisposition has been established.

Gender predisposition

• None established.

Breed/Species predisposition

• Infection in ferrets considered rare; occasional cases reported.

Public health considerations

• While actinomycosis has been extensively reported in humans, Actinomyces spp are considered part of the endogenous flora of the human mucous membranes, gastrointestinal and urogenital tracts. Human infections are primarily opportunistic infections when the mucosal or epithelial barrier is breached.
• A single report in human medicine describes possible zoonotic transmission via an animal bite.

Cost considerations

• While Actinomyces spp respond to common and readily affordable antibiotic therapy, cost of diagnostic investigations, prolonged treatment and repeated monitoring can be costly.
• Where infection is in a critical location, eg causing pleural effusion, cost of treatments to stabilize the patient, eg placement of a thoracostomy tube followed by repeated pleural drainage and lavage can become significant
• Multiple animals within a breeding colony can be affected if infection is suspected to be initiated through venereal trauma:
  • Fecundity and fertility may be affected.
  • Treatment or culling of affected animals may have a significant economic impact.

Special risks

• Actinomycosis located in the oral-cervicofacial region may result in respiratory compromise. May also interfere with placement of an endotracheal tube during anesthesia.
• Anesthetic risk may be increased in patients with thoracic actinomycosis causing pulmonary lesions and/or pleural effusion.