Felis ISSN 2398-2950

Skin: dermatophytosis

Synonym(s): Ringworm

Contributor(s): Rosanna Marsella, Ian Mason, David Scarff, David Godfrey

Introduction

  • Cause: infection with Microsporum canis most common Microsporum canis .
  • Direct and indirect transmission.
  • Common zoonosis Ringworm: human .
  • Often self-limiting.
  • Signs: variable.
  • Treatment: responds to treatment with antifungal agents  Therapeutics: non-bacterial infection.
    Print off the owner factsheet on Ringworm  Ringworm  to give to your client.

Pathogenesis

Etiology

  • Microsporum canis is the most common cause Microsporum canis .
  • Trichophyton mentagrophytes Trichophyton spp.
  • Microsporum gypseum Microsporum gypseum.
  • Other dermatophytes are rare in the cat.
  • M. canis: source is usually infected cat.
  • T. mentagrophytes: source is rodents or their environment.
  • M. gypseum: inhabits rich soil; exposure occurs during digging in contaminated areas.

Predisposing factors

General

  • Immunosuppression.
  • Breed: Persian, other long-haired breeds.

Pathophysiology

  • Transmitted by contact with infected hair and scale, fungal elements in environment or on fomites.
  • Mechanical disruption of stratum corneum facilitates infection.
  • Fungal hyphae invade hair shaft and migrate downwards; they require actively growing hair to survive.
  • Host immune response determines clinical signs; often self-limiting in healthy cats. However, chronic infections are common in long-haired cats.
  • Arthrospores germinate within 6 hours of adherence to keratinocytes.
  • Skin microtrauma is necessary for infection.
  • Grooming eliminates arthrospores from skin.
  • Fungal growth in hair  →  keratinolytic enzymes  →  penetration of cuticle and hair shaft.
  • At keratogenous zone, fungus either reaches equilibrium with keratin production or is expelled.
  • When hair enters telogen phase or inflammatory response mounted  →  spontaneous resolution.
  • Toxins produced in stratum corneum  →  cutaneous inflammation.
  • Deeper penetration of keratin surface of epidermis  →  furunculosis  →  scarring.
  • Dermatophytic pseudomycetoma in Persian cats - sub-cutaneous nodules.

Epidemiology

  • Arthrospores of Microsporum canis remain infective for 18-24 months.
  • Infection may occur from direct contact with infected cats or via fomites.

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.
  • Jacobson LS, McIntyre L, Mykusz J (2017) Comparison of real-time PCR with fungal culture for the diagnosis of Microsporum canis dermatophytosis in shelter cats: a field study. J Feline Med Surg 20 (2), 103-7 PubMed.
  • Jacobson LS, McIntyre L, Mykusz J (2017) Assessment of real-time PCR cycle threshold values in Microsporum canis culture-positive and culture-negative cats in an animal shelter: a field study. J Feline Med Surg 20 (2), 108-118 PubMed.
  • Moriello K A, Coyner K, Paterson S, Mignon B (2017) Diagnosis and treatment of dermatophytosis in dogs and cats: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology. Vet Dermatol 28 (3), 266-e68 PubMed
  • Moriello K A, Leutenegger C M (2017) Use of a commercial qPCR assay in 52 high risk shelter cats for disease identification of dermatophytosis and mycological cure. Vet Dermatol 29 (1), 66-e26 PubMed.
  • Frymus T, Gruffydd-Jones T, Pennisi M G et al (2013) Dermatophytosis in Cats: ABCD guidelines on prevention and management. J Feline Med Surg 15 (7), 598-604 PubMed.
  • Garg J, Tilak R, Garg A et al (2009) Rapid detection of dermatophytes from skin and hair. BMC Res Notes 2, 60 PubMed.
  • Patel A, Lloyd D H & Lamport A I (2005) Survey of dermatophytes on clinically normal cats in the southeast of England. JSAP 46 (9), 436-439 PubMed.
  • Moriello K A (2004) Treatment of dermatophytosis in dogs and cats: review of published studies. Vet Dermatol 15 (2), 99-107 PubMed.
  • Sparkes A H, Robinson A, MacKay A D, Shaw S E (2000) A study of the efficacy of topical and systemic therapy for the treatment of feline Microsporum canis infection. J Feline Med Surg (3), 135-142 PubMed.
  • Mancianti F, Pedonese F, Millanta F et al (1999) Efficacy of oral terbinafine in feline dermatophytosis due to Microsporum canis. J Feline Med Surg (1), 37-41 PubMed.
  • Paterson S (1999) Miconazole/chlorhexidine shampoo as an adjunct to systemic therapy in controlling dermatophytosis in cats. JSAP 40 (4), 163-166 PubMed.
  • Greisen A (1998) Dermatophytosis - Incidence of subclinical dermatophytosis in cats living in households with human dermatophytosis. JSAP (2), 43-48 VetMedResource.

Other sources of information

  • Leutenegger C (2017) Validation of a qPCR Panel to aid in the diagnosis of dermatophytosis. Abstract presented at: European College of Veterinary Internal Medicine; September 14–16, 2017; St. Julian, Malta.
  • Miller W H, Griffin C E & Campbell K L (2013) Dermatophytosis. In: Muller & Kirk's Small Animal Dermatology 7th edition, Elsevier, St Louis. pp 231-243.


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