Subcutaneous Mycoses

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FUNGI



Chromoblastomycosis


Chromomycosis


Epizootic Lymphangitis


Eumycotic Mycetoma


Hyphomycosis

  • Hyphomyces destruens
  • Opportunistic infection
    • Associated with trauma
  • Rare
  • Caused by Penicillium, Beauveria, Acremonium, Fusarium, Paecilomyces
  • Infects both animals and humans
    • Mainly affects horses
  • Tropical and semi-tropical countries
  • Progressive disease causing granulating and ulcerating lesions on the legs and lower body
    • Lesions grow rapidly
    • Cause extreme debility
  • Occurs in water
    • Most often seen in ponies with access to ponds
  • Chemotactically attracted to horse hair
  • Does not respond well to treatment
    • Radical surgical excision the best method
    • Experiemental vaccination treatment is currently underway and has shown promising results

Pythiosis

  • Causes Mycotic Swamp Fever
  • Also called phycomycosis
  • Occurs in the USA, Australia, New Guinea, India, Brazil, Colombia, Japan, Costa Rica and Indonesia
  • Pythium insidiosum
  • Granulomatous infection
    • Necrosis and fistulous tracts
    • Yellow lesions
  • Branching, separated fungi
  • Progressive (rather than systemic) disease
  • Surgery is needed

Rhinosporidiosis

  • Rhinosporidium seeberi
  • Lives in water
  • Causes a chronic, benign disease
  • Affects cattle, mules, horses, dogs and humans
  • Causes polyps on the nasal and ocular mucous membranes
    • Over 90% of cases affecting the nasal mucous membranes affects male animals
  • Occurs most frequently in tropical countries
    • Also common in the USA
  • Large sporangia can be seen on wet mounts
    • Endospores visible
    • Sporangia develop into small, globose spores
  • Treatment is by surgical excision

Sporotrichosis

Sporotrichosis in a horse -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Sporotrichosis cigar shaped cells -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Sporothrix schenckii
  • Occurs in soil, wood and vegetation
    • Saprophyte of both decaying and healthy vegetation
  • Worldwide
  • Exogenous infections through wounds
  • Sporadic infections
  • Non-contageous
  • Causes subcutaneous nodules or granulomas
    • Nodules ulcerate discharging pus
  • The bones and viscera can be involved which terminates in mortality
    • This is rare
    • Reported in dogs and horses
  • Affects dogs, horses, cats, monkeys, mules, camels, donkeys, cattle, fowl and rodents
    • Most commonly seen in horses as an ascending lymphocutaneous infection of the legs
    • Can be confused with epizootic lymphangitis in horses
  • Single cell, cigar shaped
    • Usually found within neutrophils
    • Yeast cell clusters with peripheral eosinophilic rays can be seen in tissue sections
  • Stained using PAS, Gram stain (positive), fluorescent antibody and Calcofluor White
  • Latex agglutination and immunodiffusion serology can be performed
  • Grows on Blood agar and Sabouraud's Dextrose agar in one to three weeks
    • At 37°C:
      • Colonies are smooth, cream to tan coloured and soft
      • No mycelium can be seen
    • At 25°C to 27°C:
      • Colonies turn from white and soft to tan to brown to black
      • Leathery, wrinkled and coarse
      • Mycelium can be seen as branching septate hyphae
      • Conidiospores can also be seen

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