🩺 Vesicular Stomatitis in Horses and Cattle – 2025 Vet Guide by Dr Duncan Houston

Introduction & Overview Vesicular stomatitis (VS) is a viral disease that primarily affects horses and cattle, although other livestock such as pigs and sheep can occasionally be impacted. VS is characterized by the formation of painful blisters on the tongue, lips, muzzle, nose, teats, and hooves. While VS typically causes mild to moderate illness, one of the key concerns is its similarity to foot-and-mouth disease—a far more serious and contagious viral condition.

🧫 Disease Presentation & Clinical Signs

• Oral lesions: Fluid-filled blisters on the tongue, lips, and inside the mouth. Animals may salivate excessively or resist eating due to soreness.
• Facial and muzzle sores: Open sores may form around the muzzle, nose, and lips, increasing the risk of secondary infection.
• Hoof blisters: Vesicles and erosions on the coronary band, interdigital spaces, and heels cause significant lameness or reluctance to stand.
• Udder and teat involvement: Affected cattle may develop teat and udder lesions, potentially impacting milking and causing discomfort.
• Systemic signs: Fever (up to 104°F-105°F), depression, appetite loss, and decreased milk production often accompany the blistering lesions.

🦠 Cause & Transmission

VS is caused by vesicular stomatitis virus (VSV), part of the Rhabdovirus family. There are two primary viral serotypes:

• New Jersey serotype – more common in cattle and swine;
• Indiana serotype – more frequently seen in horses.

Transmission modes include:

• Mechanical transfer by insects: Biting flies like black flies and sand flies can transmit the virus between animals.
• Direct contact: Saliva, rupture of vesicular fluid, or contaminated feed and water troughs may spread the virus.
• Fomites: Tack, grooming tools, feeders, and human hands can spread the virus within herds or barns.

📅 Seasonality & Regional Trends

VS outbreaks are tied to warm weather and increased insect activity. In 2015, for example, three horses in Pecos County, Texas, tested positive for VSV in mid-May, confirmed by the USDA lab in Ames, Iowa . These outbreaks often occur from late spring to early fall and are most common in the southern and western U.S., though sporadic cases appear in other regions. Cases are typically identified in horses but cattle can be affected simultaneously in the same geographic area.

🩹 Differential Diagnosis & Quarantine Measures

Because VS produces lesions very similar to those seen in foot-and-mouth disease (FMD), swine vesicular disease, and other vesicular infections, rapid diagnostic work is crucial.

Steps include:

• Immediate quarantine: Isolate animals, restrict transport until official testing is finalized.
• Sample collection: Submit vesicular fluid, lesion swabs, and blood to a USDA or state veterinary lab.
• Confirmatory testing: Virus isolation, PCR, or ELISA are used to confirm VSV and rule out FMD.

Confirmed outbreaks trigger regional or state-level quarantines with movement restrictions.

🚨 Human Health Implications

VS is zoonotic—humans can develop symptoms after exposure:

• Cutaneous infection: Self-limited, causes painful blisters on the fingers or lips.
• Systemic illness: Mild flu-like symptoms—fever, malaise, muscle aches— may occur.

Horse and cattle handlers should wear gloves and practice good hygiene. Report suspected human cases to public health authorities.

🔬 Diagnosis & Laboratory Testing

Diagnostic steps include:

1. Collect samples from fresh lesions—vesicular fluid or epithelial tissue.
2. Submit to diagnostic labs for virus isolation or RT-PCR confirmation.
3. Parallel testing for FMD, SVD, and other vesicular viruses to rule out foreign animal diseases.

🐎 Treatment & Animal Management

• No specific antiviral therapy exists.
• Supportive care is primary approach:
  • Pain management, soft/rich feed to encourage eating, and topical oral antiseptics.
  • Hoof blister care including hoof packing and stall rest.
  • Fluid therapy if anorexia or dehydration is evident.
• Prevent secondary infections: Lesions predispose animals to bacterial infection—topical antimicrobials or appropriate systemic antibiotics may help.
• Environmental hygiene: Disinfect feeders, waterers, boots, and tools with virucidal agents after outbreaks.

🔄 Management & Control Strategies

Quarantine protocols: Isolate affected premises; restrict all animal movement until official authorization.

Insect control:

• Install fans in barns to reduce fly landing and biting.
• Use safe insecticides/larvicides in water troughs and surroundings.
• Maintain cleanliness—remove manure and standing water to reduce vector breeding.

Minimize contact: Proper signage, restrict entry of non-essential personnel, use PPE for handlers.

Post-outbreak procedures:

• Wait at least 14 days after lesion resolution.
• Submit negative retest (PCR or virus neutralization) before lifting quarantines.
• Obtain official health certification prior to animal movement.

📝 Regulatory & Communication Aspects

Because VS can mimic foot-and-mouth disease, cases often require USDA involvement. Vet‑reported cases trigger quarantine until foreign animal diseases are ruled out.

Communication essentials:

• Notify state animal health authorities immediately upon suspecting VS.
• Implement signage and prevent unauthorized entrance.
• Contact fair and competition organizers if affected animals were moved.

📊 Prognosis & Economic Impacts

Most horses and cattle fully recover within 2–3 weeks with proper care. Mortality is rare unless complications like secondary infection occur.

Nonetheless, economic consequences can be significant:

• Lost milk production
• Weight loss from decreased feed intake
• Quarantine delays on sales or exhibitions
• Costs from veterinary treatments, diagnostics, and prolonged confinement

Despite typically mild disease, VS is taken seriously due to its trade implications. Prompt management and distancing from FMD are critical.

🌐 Regional Prevalence & 2025 Outlook

In 2015, affected horses in Texas underscored the seasonal nature and regional recurrence of VS . Similar outbreaks are reported periodically across the southwestern and central U.S., with occasional emergence in more northern areas during vector-active seasons. Vigilant pasture observation, especially in warmer months, remains key in 2025.

✔️ Key Takeaways for Farmers & Horse Owners

• VS causes painful vesicles but is generally self-limiting with supportive treatment.
• Must rule out foot-and-mouth disease—submit to official labs promptly.
• Quarantine affected premises until official clearance.
• Implement insect control, biosecurity, and maintain excellent hygiene.
• Wear gloves/contact PPE and follow sanitation to protect both animals and humans.

🔍 Final Thoughts

In 2025, **vesicular stomatitis** remains an important — though manageable — seasonal viral disease of livestock. While not deadly in most cases, its resemblance to more serious conditions like FMD necessitates careful vigilance and rapid response. Through supportive care, strict biosecurity, and communication with regulatory bodies, outbreaks can be resolved with minimal impact. Recovery is excellent with early intervention.

Stay informed, implement preventive measures, and consult your veterinarian at the first sign of blisters or lameness.