Felis ISSN 2398-2950

Microsporum canis

Synonym(s): M. canis

Contributor(s): Rosanna Marsella

Introduction

Classification

Taxonomy

  • Genus: Microsporum.
  • Perfect state: Ascomycetes.

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Clinical Effects

Epidemiology

Habitat

  • Dermatophytes may be geophilic (soil reservoir), zoophilic (animal reservoir) or anthropophilic (human reservoir).

Transmission

  • Most commonly direct contact; also fomites.
  • Source most commonly an infected cat.

Pathological effects

  • Dermatophytes are able to hydrolyze keratin and cause some damage to the epidermis and hair follicle. A hypersensitivity reaction is then mounted and the fungus moves away from the site of inflammation to normal skin. This causes the classic ringworm circular lesion with healing at the center and inflammation at the edge.
  • Lesions may occur anywhere on the body.
  • In the cat: often subclinical in adults, generally non-inflammatory except in young kittens. May become generalized in debilitated kittens.
  • In the dog: typically non-inflammatory scaly patches with alopecia. May be kerion.

Other Host Effects

  • Can cause subclinical or inapparent infection in the host animal; it may cause persistent sub-clinical infection in long-haired cats.

Control

Control via chemotherapies

  • Topical: clotrimazole Clotrimazole, tolnaftate, natamycin Natamycin, ketoconazole Ketoconazole. Lime sulfur (Lym dip) is a very effective topical.
  • Oral: griseofulvin Griseofulvin  + ketonazole (Nizoral tablets), itraconazole Itraconazole  (Spornox capsules or Itrafungol oral solution) or fluconazole Fluconazole (Diflucan tablets).

Control via environment

  • In infected cat colonies, in-contact cats should also be treated.
  • Twice weekly chlorhexideine-miconazole shampoos may help to reduce spread to other cats and human contacts.

Vaccination

  • It does prevent development of lesions after challenge.

Other countermeasures

  • Hair should be clipped from affected areas.
  • Twice weekly chlorhexideine-miconazole shampoos may be a useful adjunct to systemic therapy.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Sparkes A H, Robinson A, Mackay A D & Shau S E (2000) A study of the efficacy of topical and systemic therapy for the treatment of feline Microsporum canis infection. J Feline Med and Surg 2(3), 135-142.
  • Mancianti F, Pedonese F, Millanta F & Guarnieri L (1999) Efficacy of oral terbinafine in feline dermatophytosis due to Microsporum canis. JESFM 1, 37-41.
  • Mignon B R et al(1999) Histopathological pattern and humoral immune response to a crude exo-antigen and purified keratinase of Microsporum canis in symptomatic and asymptomatic infected cats. Med Mycol 37(1), 1-9.
  • Pier A C et al (1998) Parasitic relationship between Microsporum canis and the cat.Med Mycol 36(Suppl 1), 271-275.
  • Mancianti F et al (1998) Efficacy of oral administration of itraconazole to cats with dermatophytosis caused by Microsporum canis. JAVMA 213(7), 993-995.
  • Morielio K A & DeBoer D J (1995) Feline dermatophytosis - recent advances and recommendations for therapy. Vet Clin North Am Small Anim Pract 25(4), 901-921.

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