NAVLE Integumentary

Camelidae and Cervidae Streptococcal Dermatitis Study Guide

📅 March 28, 2026 ⏱ 25 min read 👁 2 views

Overview and Clinical Importance

Streptococcal dermatitis and related bacterial skin infections in camelids (llamas, alpacas) and cervids (deer, elk, reindeer) represent important integumentary conditions encountered in veterinary practice. While true streptococcal dermatitis is relatively uncommon as a primary diagnosis, Streptococcus species frequently act as secondary invaders in damaged skin. More commonly, bacterial skin diseases in these species include dermatophilosis (caused by Dermatophilus congolensis), staphylococcal folliculitis, and the systemic streptococcal syndrome known as alpaca fever (caused by Streptococcus equi subsp. zooepidemicus). Understanding the etiology, clinical presentation, and management of these conditions is essential for NAVLE success.

Disease Form	Clinical Features	Prognosis
Local/Superficial	Wound infection, mastitis, septic orchitis; localized abscess formation	Good with appropriate treatment
Systemic (Alpaca Fever)	Polyserositis (peritonitis, pleuritis), meningitis, endocarditis; fever, depression, sudden death	Guarded to poor; 50-100% mortality in Peru

Etiology and Classification of Bacterial Skin Infections

Streptococcal Infections in Camelids

Streptococcus equi subsp. zooepidemicus is a Lancefield group C streptococci that causes both localized and systemic disease in camelids. This organism is considered a commensal in South American alpacas but is not a normal flora in North American populations, making these animals more susceptible to severe infection upon exposure.

Forms of Streptococcal Disease in Camelids

High-YieldOn the NAVLE, remember that alpaca fever (S. equi subsp. zooepidemicus) causes POLYSEROSITIS with fibrinous exudate in thoracic and abdominal cavities. Stressors like transport, malnutrition, and overcrowding precipitate systemic infection in subclinical carriers. Horses may serve as reservoirs.

Dermatophilosis (Rain Rot)

Dermatophilosis, also known as rain rot, lumpy wool disease, or streptotrichosis, is caused by Dermatophilus congolensis, a gram-positive, actinomycete bacterium with a life cycle resembling fungi. Despite the name "streptotrichosis," this is NOT caused by Streptococcus species. The organism exists in two morphologic forms: motile flagellated zoospores (infective stage) and branching hyphae.

Key Predisposing Factors for Dermatophilosis

NAVLE TipThe TWO most important predisposing factors for dermatophilosis are MOISTURE and SKIN DAMAGE. The organism has NEVER been isolated from soil, persisting only on animal hosts and dried crusts.

Other Bacterial Skin Infections

Bacterial Folliculitis and Furunculosis

Folliculitis (hair follicle inflammation) and furunculosis (hair follicle rupture) are common bacterial skin conditions in camelids. The most commonly implicated organisms are Staphylococcus aureus and S. intermedius. Predisposing factors include trauma, moisture, insect bites, contact dermatitis, and immunodeficiency. Clinical presentation includes erythema, papules, pustules, yellowish crusts, and epidermal collarettes with minimal pruritus.

Munge (Idiopathic Hyperkeratotic Dermatosis)

Munge is a severe dermatitis syndrome in camelids characterized by heavy, adherent, hyperkeratotic crusts primarily affecting paranasal and perioral regions. It is considered a cutaneous reaction pattern that may be provoked by multiple underlying conditions including bacterial folliculitis, dermatophilosis, dermatophytosis, viral infections, sarcoptic mange, contact dermatitis, and zinc-responsive dermatosis. Secondary bacterial infection with Streptococcus and Staphylococcus species is common.

Factor	Mechanism
Prolonged moisture/wetness	Releases motile zoospores; macerates stratum corneum
Skin damage	Provides portal of entry; from insects, ticks, shearing wounds, or vegetation
Ectoparasite infestation	Ticks and lice cause skin damage; mechanical transmission
Immunosuppression	Concurrent illness, malnutrition, stress reduce host resistance

Clinical Signs and Species-Specific Presentations

Camelids (Llamas and Alpacas)

Cervids (Deer, Elk, Reindeer)

In cervids, Streptococcus and Staphylococcus species typically cause secondary bacterial dermatitis following primary insults. Dermatophilosis is the most commonly diagnosed bacterial skin disease in free-ranging white-tailed deer, particularly in wet conditions or in animals congregating at feeders.

High-YieldDermatophilosis in deer is a common feeder-associated disease. When deer congregate at feeding sites in wet conditions, transmission is facilitated. Most cases are self-limiting and resolve within 3 weeks with dry weather.

Condition	Clinical Signs	Distribution
Dermatophilosis	Wet, clumped wool; paint brush crusts; erythematous erosions when crusts removed; non-pruritic	Dorsal midline, back, sides, distal extremities
Bacterial Folliculitis	Papules, pustules, epidermal collarettes, yellowish crusts; mild pruritus	Head, back, ventrum, distal extremities
Munge	Heavy, tightly adherent hyperkeratotic crusts; may obstruct nostrils; waxing and waning course	Paranasal, perioral, bridge of nose, periocular, periaural
Alpaca Fever (Systemic)	Fever, depression, dyspnea, cyanosis, abdominal distension, colic, recumbency; acute death possible	Systemic (thoracic/abdominal polyserositis)

Diagnostic Approach

Cytology (Gold Standard for Dermatophilosis)

Direct microscopic examination of stained crusts is the primary diagnostic method for dermatophilosis. The technique involves mincing crusts with water on a glass slide, allowing to dry, then staining with Gram stain or Giemsa. D. congolensis appears as gram-positive, branching, multiseptate filamentous bacteria arranged in characteristic railroad track patterns with parallel rows of coccoid cells.

Diagnostic Methods Comparison

Exam Focus: Histopathology of dermatophilosis shows characteristic PALISADING CRUST with alternating layers of orthokeratosis, parakeratosis, and inflammatory cells. Organisms are embedded within the crust.

Differential Diagnosis

Dermatophytosis (ringworm) - circular lesions, Wood's lamp/DTM positive
Sarcoptic mange - PRURITIC; skin scraping or biopsy for mites
Chorioptic mange - affects lower limbs; less pruritic than sarcoptic
Zinc-responsive dermatosis - ventral distribution; responds to zinc supplementation
Pemphigus foliaceus - immune-mediated; histopathology diagnostic
Contagious viral pustular dermatitis (orf) - proliferative lesions; PCR/EM for parapoxvirus
Contact dermatitis - ventral distribution; history of exposure

Condition	Clinical Signs	Key Features
Dermatophilosis	Raised, matted hair tufts (paint brush appearance); crusty scabs; alopecia; raw/bleeding skin under crusts	Most common in young males; affects face, ears, back, legs; often feeder-associated
Secondary Bacterial Dermatitis	Purulent exudate, pustules, crusting overlying wounds or viral lesions	Commonly Staphylococcus and Streptococcus spp.; often secondary to viral disease
Contagious Ecthyma (Reindeer)	Proliferative cauliflower-like lesions at mucocutaneous junctions; secondary bacterial infection common	Parapoxvirus primary; F. necrophorum and streptococci secondary; ZOONOTIC

Treatment Protocols

Dermatophilosis Treatment

Most cases of dermatophilosis will spontaneously regress within 2-3 weeks with the advent of dry weather. Treatment focuses on keeping animals dry, improving overall health through nutrition and parasite control, and addressing secondary infections when necessary.

Alpaca Fever (Streptococcal Polyserositis) Treatment

High-YieldS. equi subsp. zooepidemicus is HIGHLY susceptible to penicillin. However, early aggressive treatment is critical as mortality can reach 50-100% once systemic infection is established. Rapid clinical improvement (within 24 hours) suggests favorable response to treatment.

Method	Indication	Advantages	Limitations
Cytology	All crusting dermatoses; pustules; exudate	Rapid, inexpensive, field-applicable; diagnostic for D. congolensis	May be negative in chronic/healing lesions
Bacterial Culture	Equivocal cytology; treatment failure; species ID needed	Definitive identification; sensitivity testing	D. congolensis requires microaerophilic CO2 conditions
Histopathology	Chronic/atypical cases; munge; rule out immune-mediated disease	Palisading crust pathognomonic for dermatophilosis	More expensive; longer turnaround
Skin Scraping	Rule out sarcoptic/chorioptic mange (differential)	Essential for differential diagnosis	May require multiple scrapings or biopsy for sarcoptic mange

Prevention and Control

Environmental management: Provide adequate shelter; avoid overcrowding; minimize wet/muddy conditions
Stress reduction: Minimize transport stress; avoid abrupt diet changes; maintain adequate nutrition
Ectoparasite control: Regular treatment for ticks, lice, and biting flies that damage skin and transmit organisms
Quarantine: Isolate new animals; avoid mixing species (separate horses from camelids)
Hygiene: Disinfect shearing equipment between animals; proper wound care after shearing
Fomite control: Change clothing between handling horses and camelids; equipment disinfection

Treatment	Dosage/Protocol	Notes
Environmental Management	Keep animals DRY; provide shelter; improve nutrition	Most important intervention; moisture control essential
Topical Therapy	Chlorhexidine 2-4%; Lime sulfur 2-3%; Dilute iodine; daily for 3-5 days then weekly	Gentle crust removal; ensure complete drying after application
Procaine Penicillin G	22,000-66,000 IU/kg SC or IM q24h for 5-7 days	Drug of choice for D. congolensis; combine with streptomycin for severe cases
Long-acting Oxytetracycline	20 mg/kg IM single dose	Alternative for herd outbreaks; single dose may halt outbreak

Zoonotic Considerations

Both dermatophilosis and S. equi subsp. zooepidemicus infections have zoonotic potential. Human dermatophilosis infections typically result from direct contact with infected animals and cause self-limiting pustular skin lesions. Immunocompromised individuals may develop more severe infections. S. equi subsp. zooepidemicus can cause severe human disease including meningitis, endocarditis, and septicemia, particularly in immunocompromised individuals or following consumption of unpasteurized dairy products.

Precautions: Wear gloves when handling infected animals; wash hands thoroughly after contact; avoid consumption of unpasteurized dairy from camelids; advise immunocompromised individuals to avoid direct animal contact.

Drug	Dosage	Notes
Ceftiofur sodium	5 mg/kg IV q12h	First-line parenteral; broad-spectrum coverage
Ampicillin sodium	12 mg/kg IV q12h	Alternative parenteral; all streptococci highly susceptible
Flunixin meglumine	1 mg/kg IV q12h	Anti-inflammatory; address sepsis/endotoxemia
Supportive Care	IV fluids; pleural drainage if needed	Critical for survival; address dehydration and effusions

Memory Aids and Board Tips

DERM-WET Mnemonic for Dermatophilosis:

D - Dermatophilus congolensis (actinomycete, NOT Streptococcus)
E - Environmental moisture is KEY predisposing factor
R - Railroad track appearance on cytology
M - Matted hair tufts (paint brush crusts)
W - Worldwide distribution; worse in WET seasons
E - Erosions/erythema under removed crusts
T - Treatment: Keep DRY + Penicillin

ALPACA FEVER Quick Facts:

A - Acute onset; often follows STRESS
L - Lancefield group C streptococcus
P - Polyserositis (peritonitis + pleuritis)
A - Animals (horses) may be reservoir
C - Commensal in South America, NOT in North America
A - Aggressive treatment needed; high mortality

NAVLE TipWhen a NAVLE question mentions crusting dermatosis in a llama or alpaca with recent wet weather or shearing history, think DERMATOPHILOSIS first. The key diagnostic finding is the railroad track appearance of D. congolensis on cytology. If the question mentions acute death, fever, and pleural/abdominal effusion in an alpaca following transport stress, think ALPACA FEVER (S. equi subsp. zooepidemicus polyserositis).

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