Dermatophilosis

Also known as: Cutaneous streptothrichosis

Introduction

This is a group of diseases affecting the epidermis caused by Dermatophilus congolensis. It causes a range of conditions in large animals including rain scald in horses and strawberry foot rot in sheep. The disease is associated with skin trauma, prolonged wetting or parasites. Lesions typically involve exudative dermatitis with scab formation. It is a zoonosis affecting humans in close contact with infected animals.

Signalment

Can be seen in animals of all ages but most commonly occurs in young animals who are chronically exposed to moisture. Affects horses, sheep, cattle, goats, pigs and rarely dogs and cats.

History and Clinical signs

Lesions commonly occur following heavy rainfall and commonly affects the dorsum of animals. Any previous trauma or damage to the skin can predispose to infection. Blood-sucking insects are also thought to be involved in transmission.

Equine dermatophilosis

Ovine dermatophilosis

Bovine dermatophilosis

Diagnosis

Diagnosis can often be made on history and physical exam. Impression smears can also be useful when stained with either gram stain or Giemsa and examined microscopically.

Additionally it is possible to culture material from the crusts however this can be difficult due to the slow growing nature of the pathogen.

Pathology

Grossly: Papules, pustules, crusts may coalesce and mat the coat.

Microscopically:

• Hyperplastic superficial perivascular dermatitis
• Multilaminated crusts, alternating keratin and inflammatory cell layers

Prognosis

Good if animals are kept dry. Often re-occurs in wet weather.

Literature Search

Use these links to find recent scientific publications via CAB Abstracts (log in required unless accessing from a subscribing organisation).


Dermatophilosis publications since 2000

References

Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial

4th year Veterinary Dermatology notes. Royal Veterinary college. October-November 2008. p60-64.