Vesicular Stomatitis in Animals
Introduction
Vesicular Stomatitis (VS) is a viral disease of livestock characterized by the formation of vesicles and erosions in the mouth, on the feet, and occasionally on the teats. Clinically, it closely resembles Foot-and-Mouth Disease (FMD), making it a significant differential diagnosis in vesicular disease outbreaks. The disease affects cattle, horses, and pigs, and has important economic and regulatory implications.
Etiology
Causative Agent
Vesicular Stomatitis is caused by Vesicular Stomatitis Virus (VSV), a member of the genus Vesiculovirus in the family Rhabdoviridae.
Virus Characteristics
- Enveloped, single-stranded negative-sense RNA virus
- Two main serotypes: Indiana and New Jersey
- Heat and desiccation sensitive compared to FMD virus
Epidemiology
Species Affected
- Cattle (most commonly affected livestock species)
- Horses (often show severe lesions)
- Pigs (less commonly affected)
- Occasional infections in sheep and goats
Geographic Distribution
Vesicular stomatitis occurs in the Americas, particularly in North, Central, and parts of South America. Outbreaks are often seasonal and geographically limited.
Transmission
- Biting insects (especially sandflies and blackflies) are major vectors
- Direct contact with infected animals
- Contaminated feed, water, or fomites
- Mechanical transmission via equipment and handlers
Risk Factors
- Warm and humid climates favoring insect vectors
- Proximity to wildlife reservoirs
- Outdoor housing systems
Pathogenesis
Entry and Replication
The virus enters through skin abrasions or mucous membranes and replicates locally in epithelial cells.
Lesion Development
- Virus causes degeneration of epithelial cells
- Fluid accumulation leads to vesicle formation
- Vesicles rupture, resulting in erosions and ulcers
Systemic Spread
Systemic infection is rare; disease is generally localized to epithelial surfaces.
Clinical Signs
General Signs
- Fever (mild or transient)
- Depression
- Reduced feed intake
Oral Lesions
- Vesicles on tongue, gums, lips, and dental pad
- Drooling (excess salivation)
- Painful erosions after vesicle rupture
Foot Lesions
- Vesicles in interdigital space and coronary band
- Lameness
Species Differences
- Cattle: oral and foot lesions common
- Horses: severe oral lesions, reluctance to eat
- Pigs: less common, mild lesions
Summary for Practitioners
Vesicular stomatitis must always be considered in outbreaks of vesicular disease, especially in endemic regions. It is clinically indistinguishable from FMD without laboratory confirmation.
Postmortem Findings
Gross Lesions
- Vesicles and ulcers in oral cavity
- Lesions on feet and occasionally teats
- No significant internal organ lesions
Microscopic Lesions
- Degeneration of epithelial cells
- Intraepithelial vesicle formation
- Inflammatory cell infiltration
Diagnosis
Clinical Diagnosis
Based on vesicular lesions; must be differentiated from FMD and other vesicular diseases.
Laboratory Diagnosis
- PCR for viral RNA detection
- Virus isolation
- Serological testing (ELISA)
Differential Diagnosis
- Foot-and-Mouth Disease (FMD)
- Swine vesicular disease
- Vesicular exanthema
Summary for Practitioners
Because of its similarity to FMD, any suspected case must be treated as a high-priority report until laboratory confirmation excludes FMD.
Treatment
Supportive Care
- Soft feed and adequate hydration
- Topical antiseptics for lesions
- NSAIDs for pain and inflammation
Prognosis
Generally good, with most animals recovering within 1–2 weeks.
Summary for Practitioners
Treatment is supportive only. Recovery is usually complete, but secondary infections should be monitored.
Control and Prevention
Vector Control
- Control of biting insects (flies, sandflies)
- Use of insect repellents and insecticides
Biosecurity
- Isolation of affected animals
- Disinfection of equipment
Movement Control
- Restrict animal movement during outbreaks
- Surveillance in affected regions
Summary for Practitioners
Control focuses on insect vector management and biosecurity. Because outbreaks are sporadic, surveillance is essential in endemic areas.
Zoonotic Importance
Vesicular stomatitis is zoonotic and can cause flu-like illness and vesicular lesions in humans handling infected animals.
Economic Importance
The disease causes economic losses due to decreased productivity, trade restrictions, and costs associated with disease investigation and quarantine measures.
Summary
Vesicular stomatitis is an important vesicular disease of livestock caused by a rhabdovirus and transmitted mainly by insect vectors. It closely resembles FMD clinically and requires laboratory confirmation for diagnosis. Control relies on vector management, biosecurity, and surveillance.
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