Camelidae and Cervidae Necrotic Stomatitis Study Guide

Overview and Clinical Importance

Necrotic stomatitis (oral necrobacillosis) is a serious infectious disease affecting the oral cavity of camelids (llamas, alpacas) and cervids (deer, elk, reindeer). The condition is characterized by necrotizing, ulcerative lesions of the oral mucosa caused primarily by Fusobacterium necrophorum, a gram-negative, obligate anaerobic bacterium. This disease represents a significant cause of morbidity and mortality in both domestic and wild populations of these species.

In camelids, necrotic stomatitis is relatively uncommon but can occur as part of a broader syndrome called alimentary necrobacillosis, which may involve the esophagus and gastric compartments. In cervids, the disease is more commonly recognized as part of the lumpy jaw complex or can present as primary oral lesions, particularly in farmed deer populations where it represents one of the most economically important diseases.

Etiology

Primary Causative Agent

Fusobacterium necrophorum is the primary etiologic agent of necrotic stomatitis. Key characteristics include:

• Gram-negative, non-motile, non-sporulating, pleomorphic rod-shaped to filamentous bacterium
• Obligate anaerobe (aerotolerant-to-anaerobic)
• Normal inhabitant of the alimentary and urogenital tracts
• Does NOT penetrate healthy mucosa - requires breach in mucosal integrity

Subspecies

Virulence Factors

Co-Infecting Agents

Necrotic stomatitis is often polymicrobial. Common co-infecting agents include:

• Trueperella pyogenes (formerly Arcanobacterium pyogenes) - synergistic relationship with F. necrophorum
• Actinomyces bovis - causes lumpy jaw; often concurrent in cervids
• Pseudomonas spp. - opportunistic; associated with environmental contamination

Pathogenesis

Disease Development Sequence

• Mucosal Damage: Initial breach in oral mucosa from trauma, coarse feed, dental eruption, or concurrent disease
• Bacterial Invasion: F. necrophorum colonizes damaged tissue; anaerobic environment created in wound favors growth
• Leukotoxin Production: Destruction of neutrophils and macrophages impairs local immune response
• Coagulative Necrosis: Extensive tissue necrosis with foul-smelling discharge; characteristic lesion formation
• Potential Spread: Bacteremia may lead to metastatic lesions in liver, lungs, or other organs

Predisposing Factors

Clinical Signs and Presentation

Camelidae (Llamas and Alpacas)

Clinical presentation in South American camelids includes:

• Anorexia and depression - often the first sign noticed
• Dysphagia - difficulty swallowing; drooling/ptyalism
• Halitosis - foul-smelling breath (characteristic)
• Oral lesions: Multifocal-to-coalescing ulcers on tongue, cheeks, and oral mucosa
• Weight loss - progressive emaciation
• Pyrexia - elevated temperature in acute cases
• Extension to GI tract - esophageal and gastric compartment involvement (C1, C2, C3)

Cervidae (Deer, Elk, Reindeer)

Clinical signs in cervids include:

• Swollen jaws or cheeks - 'lumpy jaw' appearance
• Necrotic oral lesions - ulcers with yellow-green purulent discharge
• Drooling and difficulty eating - feed dropping from mouth
• Weight loss and poor condition - dry coat, separation from herd
• Mandibular or maxillary swelling - hard, immovable masses at molar level
• Draining fistulous tracts - in advanced cases with abscess formation

Pathological Findings

Gross Lesions

Histopathological Features

• Coagulative necrosis - central necrotic core with amorphous debris
• Leukocyte destruction zone - rim of wholesale neutrophil destruction with dissipated nuclear chromatin
• Filamentous bacteria - concentrated at advancing edge of necrosis
• Peripheral hyperemia and hemorrhage - surrounding viable tissue shows severe vascular changes
• Local vessel thrombosis - common finding adjacent to necrotic foci

Diagnosis

Diagnostic Approach

Differential Diagnosis

Exam Focus: Differentiate NECROBACILLOSIS (soft tissue necrosis, foul odor, F. necrophorum) from ACTINOMYCOSIS (bone involvement, slow-growing, A. bovis, sulfur granules) and ACTINOBACILLOSIS (soft tissue only, wooden tongue, A. lignieresii). These three conditions can occur concurrently!

Treatment

Antimicrobial Therapy

Early treatment is critical - once lesions become established with abscess formation, response to therapy is poor.

Note: Most drugs are NOT licensed for use in camelids or cervids. Consult with a veterinarian for extra-label drug use guidance.

Supportive Care

• NSAIDs: Flunixin meglumine (1.1 mg/kg IV) or meloxicam for pain and inflammation
• Local wound care: Debridement of necrotic tissue; flush with dilute iodine or chlorhexidine
• Abscess drainage: Lance and drain abscesses; flush cavity; may need repeated treatment
• Nutritional support: Soft feeds; ensure adequate hydration; may need assisted feeding
• Isolation: Separate affected animals to prevent environmental contamination

Surgical Intervention

For advanced cases with significant bone involvement:

• Surgical debridement of necrotic bone
• Curettage of mandibular/maxillary abscesses
• Combined with prolonged antimicrobial therapy

Prognosis

Prevention and Control

Management Strategies

Zoonotic Considerations

F. necrophorum can rarely be transmitted to humans from handling animals with open sores or pus. In humans, F. necrophorum can cause:

• Lemierre syndrome - post-anginal septicemia with jugular vein thrombophlebitis
• Pharyngitis, peritonsillar abscess
• Skin and soft tissue infections

Always wash hands and exposed skin areas with soap and disinfectant after working with infected animals. Use appropriate PPE.

Memory Aids and Board Tips

FUSO Mnemonic for Necrotic Stomatitis

F = FOUL odor (characteristic halitosis)

U = ULCERATIVE, necrotic lesions

S = SECONDARY to mucosal damage (never primary infection)

O = OBLIGATE anaerobe (Fusobacterium necrophorum)

The 'LUMPY' Memory Aid for Cervid Necrobacillosis

L = Lesions at molar level

U = Ulcers with yellow-green pus

M = Mandibular swelling (hard, immovable)

P = Poor response if bone involved

Y = Young animals (fawns) especially susceptible during dental eruption