Actinomyces infection in Lagomorphs and Ferrets

• See also: Abscessation in Lagomorphs and Ferrets

• Actinomyces spp. is rarely linked with abscessation in ferrets. (B602.10.w10)
  • Being a normal inhabitant of the oral cavity (B232.10.w10), Actinomyces is primarily associated with secondary infection after oral mucosa trauma or internal abscessation after the organism is swallowed or inhaled. (B602.10.w10)
  • Actinomyces spp. are normally present in a ferret's mouth. When there is trauma the bacteria can invade the tissues of the head, neck and lungs. (B232.10.w10)

Clinical

Rabbits

• Actinomyces spp. infection in rabbits has been reported in cases of osteitis involving bones of the vertebral column, head, and distal extremities. (B614.8.w8)

Ferrets

• Lumpy jaw lesions (dense compact swelling - nodule or abscess) on the neck. (B631.24.w24)

• High temperature. (B232.10.w10)

• Sinus tracts may be formed and yellow-green pus may discharge from the lesion. (B602.10.w10, B631.24.w24)
• With large lesions, dyspnoea may develop. (B602.10.w10, B627.14.w14)
• A pregnant female ferret developed two hard masses in the neck (one at the thoracic inlet, the other in the nuchal region), with skin over the lesions thickened. Sinuses developed over the dorsal lesions. The masses became larger and towards the end of pregnancy the ferret became dyspnoic. Her general condition deteriorated and she died soon after giving birth. (J42.64.w1)

Pathology

Gross pathology

Rabbits

• Skeletal: bone lysis and proliferation, and granulomatous inflammation containing "sulphur granules"; inflammation extended into adjacent soft tissue. (B614.8.w8)

Ferrets

• A chronic pyogranulomatous mass that contains sulphur granules (pockets of yellow-green material in the fibrous mass). (B232.10.w10)
• In one ferret, cervical masses and sinuses. (B627.14.w14)
  • A dorsal 5 cm diameter fibrotic mass containing many small abscesses of thick, green-yellow pus; sinuses led from these to the overlying, thickened skin. The mass was adherent to the overlying skin and to the adjacent muscles. The ventral mass was similar but without sinuses. (J42.64.w1)
• In a ferret which died without clinical signs, on the lung, firm nodules under the pleura, and enlarged posterior mediastinal lymph nodes; the cut surface revealed abscesses containing greenish granules. (B627.14.w14)

Histopathology:

• Cervical masses: organising granulation tissue containing many discrete and confluent abscesses. In the purulent exudate, mainly polymorphonuclear leucocytes, also many macrophages. Around each abscess, granulation tissue with neutrophil infiltration; further from each abscess, a greater degree of fibroblastic proliferation and fibrosis. Areas of dense sclerosis were noted. The lesions were not encapsulated but were infiltrating into the muscle and dermis. In haematoxylin and eosin preparations, typical Actinomyces colonies were easily visible, reaching as large as 0.4 cm diameter; Gram-negative  club-like structures were found on the surface of colonies and branching filaments within the colonies. (J42.64.w1)
• In a ferret which died without clinical signs, abscesses contained typical Actinomyces colonies. (B627.14.w14)

Human Health Considerations

• Actinomyces spp. although rare in ferrets, are common causes of opportunistic infection in humans infected with the human immunodeficiency virus (HIV). (B602.10.w10)
  • Strict hand hygiene should always be observed when handling a ferret with a draining abscess. (B540.7.w7, B633.13.w13)
  • Gloves, masks and protective clothing should be worn when handling or treating the infected area. (V.w147)
  • All individuals coming into contact with the ferret should be fully aware of the zoonotic risk. (V.w147) 

Susceptibility/Transmission

Ferrets

• Infection follows puncture wounds to the oral mucosa, or when the bacteria are inhaled or swallowed. (B602.10.w10)
• Possible increased susceptibility with lymphoma: a subcutaneous granuloma cultured positive for Actinomyces spp. in a ferret with lymphoma. (B602.10.w10) [This finding was reported in a single case study only].

Diagnosis

Ferrets

• A biopsy or aspirate from the mass to distinguish between abscessation, neoplasia and Hypoderma bovis infection. (B627.14.w14)
• Presence of clumps of filamentous, Gram-positive bacilli provides a presumptive diagnosis, further confirmed by carbolfuschin acid-fast staining. Bacterial culture of an aspirate or punch biopsy to confirm the organism. (B660.41.w41)
  • Submit anaerobically and inform laboratory personnel that an actinomycete is suspected. (B660.41.w41)

Differential diagnosis

Ferrets

• Abscessation in Lagomorphs and Ferrets [caused by a variety of other bacteria]
• Neoplasia in Ferrets (B627.14.w14)
• Hypoderma bovis (Warble) Infection in Ferrets. (B627.14.w14)
• Cervical cellulitis (Staphylococcus spp. or Streptococcus spp.) secondary to mandibular osteomyelitis. (B627.14.w14, J42.64.w1)

Treatment

Ferrets

• Treatment for lumpy jaw is to curette, drain, and start the ferret on antibiotics. (B631.24.w24)
• Recommended antibiotic treatment protocol (depending on the results of a sensitivity test)  (B232.10.w10, B602.10.w10) for Actinomyces spp. infections:
  • High doses of penicillin G - 40,000 IU/kg by sub-cutaneous injection once daily (B631.24.w24) OR
  • High doses of tetracycline - 25 mg/kg orally once daily. (B631.24.w24) OR
  • Cephalosporins (e.g. cephalexin) subject to the antibiotic sensitivity results (B232.10.w10, B651.9.w9)
• Offer liquid food, especially if the ferret is finding eating difficult due to swelling of the tissues of the neck. (B232.10.w10)

• Environmental Assessment
• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Imaging in Lagomorph Diagnosis and Treatment
• Imaging in Ferret Diagnosis and Treatment
• Clinical Pathology of Lagomorphs
• Clinical Pathology of Ferrets
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

• Mustela putorius furo
• Oryctolagus cuniculus domesticus - Domestic European rabbit