Canis ISSN: 2398-2942

Fungal lung disease: blastomycosis

Contributor(s): Prof Susan Bunch, Rhea Morgan, Elizabeth Rozanski

Introduction

  • Systemic mycotic infection.
  • Etiological agent:dimorphic fungusBlastomyces dermatitidis Blastomyces dermatitidis.
  • Signs of infection:respiratory system, eyes, skin, lymph nodes, and bone.
  • Route of infection:inhalation.
  • Diagnosis:characteristic pulmonary changes in a young, large breed, male dog.
  • Identification:in cytological or histopathological samples.
  • Treatment:Itraconazole and other antifungal agents.
  • Prognosis:Good to fair.

Pathogenesis

Etiology

Predisposing factors

General
  • Exposure to a common source in an endemic area.
  • Large-breed, young male dogs (1-5 years of age; most common age = 2 years).
  • Subclinical infection may occur, and immune-compromise of the animal may predispose to the development of clinical disease.

Pathophysiology

  • The dimorphic yeast organism usually gains entry into the body via inhalation.
  • Organism converts into a yeast form at body temperature.
  • Infection first develops in the lungs, then disseminates via hematogenous and lymphatic routes to the rest of body. Specific target organs include the eyes, bone, brain, skin, soft tissues, lymph nodes and testes.

 

  • Organisms cause a pulmonary infection.
  • Immune system mounts response to clear infection, with variable success.
  • Host immune system failure -> generalized infection -> host death.

Timecourse

  • Incubation time -> 5-12 weeks.

Epidemiology

  • Exists in concentrated areas within endemic areas.
  • Several dogs in a neighborhood or household may be affected.
  • Dogs are more susceptible to infection, so may be considered a sentinel for human infection.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Arceneaux K A, Taboada J & Hosgood G (1998) Blastomycosis in dogs: 115 cases (1980-1995). J Am Vet Med Assoc 213 (5), 658-664 PubMed.
  • Bloom J D, Hamor R E & Gerding P A Jr (1996) Ocular blastomycosis in dogs - 73 cases, 108 eyes (1985-1993)J Am Vet Med Assoc 209 (7), 1271-1274 PubMed.
  • Krawiec D R, McKiernan B C, Twardock R et al (1996) Use of amphotericin B lipid complex for treatment of blastomycosis in dogs. J Am Vet Med Assoc 209 (12), 2073-2075 PubMed.
  • Legendre A M, Rohrbach B W, Toal R L et al (1996) Treatment of blastomycosis with itraconazole in 112 dogs. J Vet Intern Med 10 (6), 365-371 PubMed.
  • Garma-Aviña A (1995) Cytologic findings in 43 cases of blastomycosis diagnosed ante-mortem in naturally-infected dogsMycopathologia 131 (2), 87-91 PubMed.
  • Rudmann D G, Coolman B R, Perez C M et al (1992) Evaluation of risk factors of blastomycosis in dogs: 857 cases (1980-1990). J Am Vet Med Assoc 201 (11), 1754-1759 PubMed.

Other sources of information

  • Legendre A M (1998)Blastomycosis. In: Green C E (ed)Infectious diseases of the Dog and Cat.2nd Ed. W B Saunders, Philadelphia, pp 371-377.


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