NAVLE Integumentary

Camelidae and Cervidae Dermatophilosis Study Guide

Dermatophilosis (also known as rain rot, rain scald, lumpy wool disease, or streptothricosis) is an important bacterial skin disease caused by Dermatophilus congolensis, a Gram-positive, facultative anaerobic actinomycete.

Overview and Clinical Importance

Dermatophilosis (also known as rain rot, rain scald, lumpy wool disease, or streptothricosis) is an important bacterial skin disease caused by Dermatophilus congolensis, a Gram-positive, facultative anaerobic actinomycete. This organism affects multiple species including camelids (llamas, alpacas) and cervids (deer, elk, moose), making it a relevant topic for both NAVLE and BCSE examinations.

The disease has significant economic implications in the livestock industry due to its effects on fiber quality in camelids and leather/hide quality in all affected species. Additionally, D. congolensis is a zoonotic organism, making proper diagnosis and biosecurity measures essential for veterinary professionals.

High-YieldRemember that D. congolensis is NOT a fungus despite its fungal-like life cycle with zoospores and hyphae. It is an actinomycete bacterium. The historic misnomer 'mycotic dermatitis' is incorrect and should not be used.
Form Characteristics Clinical Significance
Zoospores Flagellated, ovoid cells (0.6-1.0 micrometers) Motile in presence of moisture Dormant stage that persists on skin, hair, and dried crusts INFECTIVE STAGE Can persist for months in environment Released by moisture/warmth
Filamentous Hyphae Branching filaments (1-5 micrometers diameter) Fragment by transverse and longitudinal septation Form packets of coccoid cells in parallel rows INVASIVE STAGE Creates characteristic 'railroad track' appearance on cytology Invades viable epidermis

Etiology and Organism Characteristics

Organism Classification

Dermatophilus congolensis was first identified in 1915 from cattle in Zaire (former Belgian Congo), giving the organism its species name. Key taxonomic characteristics include:

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