Fungi and Candidiasis in Pets

Fungi Forms

• Yeast forms have predisposing factors in dogs or cats with local or disseminated candidiasis, including Diabetes Mellitus (DM), immunosuppressive drugs, and broad-spectrum antibacterial drugs.

Opportunistic Fungi

• Some fungi are opportunistic, causing disease under predisposing conditions such as DM, immunosuppressive therapy, malignancy, burns, and immunodeficient diseases like AIDS.
• Examples of opportunistic fungi include Candidiasis, Aspergillosis, and Cryptococcosis.

Aspergillosis

• Aspergillosis is characterized by oral and upper respiratory disease, Pyothorax, and inhalation of spores as a route of transmission.
• The infection can extend to the central nervous system (CNS) through the cribriform plate of the ethmoid bone.
• Ingestion of spores leads to colonization and invasion of the gastrointestinal tract, resulting in intra-abdominal involvement.
• Clinical signs include:
  • Fever
  • Respiratory signs such as dyspnea and tachypnea
  • Ocular signs
  • Lameness
  • Skin lesions
  • Peripheral lymphadenopathy

Disseminated Aspergillosis

• Multifocal, pale, tan to white nodules within kidneys, liver, pancreas, and pleura
• Granulomatous or pyogranulomatous inflammation with abundant intralesional fungal hyphae in various tissues
• Infarcts (secondary to thrombi) containing fungal elements found in the spleen, kidneys, and liver
• Fibrinoid necrotizing vasculitis with associated hemorrhage
• Mottled and congested lung lobes
• Serosanguinous pleural effusion
• Splenic infarction

Dermatophytosis (Trichophytosis, Ringworm)

• Caused by Microsporum and Trichophyton spp
• Most common species affecting dogs and cats are Microsporum canis and Trichophyton mentagrophytes
• Clinical diagnosis:
  • Examination of the haircoat with an ultraviolet lamp (Wood's lamp)
  • Some dermatophyte species, including M.canis, glow yellow-green under the lamp