Vet Guide to Botvax® B in 2025 🐴💉

Hello, I’m Dr Duncan Houston, BVSc, founder of Ask A Vet. In this in-depth 2025 guide, we explore Botvax® B, the only USDA-approved vaccine to prevent equine botulism type B. This vaccine is essential for horses at risk from haylage, silage, or contaminated environments. Let’s review how it works, dosing schedules, broodmare protocols, and expert veterinary recommendations. 🩺

📘 What Is Botulism & Why Vaccinate?

Equine botulism is a deadly paralytic disease caused by the neurotoxins of Clostridium botulinum. In the U.S., type B is the most common strain affecting horses—especially foals (“shaker foal syndrome”) and horses exposed to improperly stored haylage or silage. Mortality rates are high without early treatment, making prevention via vaccination critical. 💀

✅ What Is Botvax® B?

Botvax® B (Neogen) is an inactivated toxoid vaccine designed to stimulate protective immunity against Clostridium botulinum type B. It’s safe for use in all horses and is especially recommended in areas where botulism is endemic or haylage feeding occurs.

📐 Vaccination Protocols

🐴 Adult Horses (Never Vaccinated Before)

• Initial series: 3 doses, **4 weeks apart**
• Annual booster every 12 months thereafter

🤰 Broodmares

• Initial series (3 doses) completed before pregnancy
• Annual **booster 4–6 weeks pre-foaling** to protect colostral antibodies for foal 🍼

🍼 Foals (Born to Vaccinated Mares)

• Start at **2–3 months of age**
• 3-dose series, 4 weeks apart
• Annual boosters thereafter

🍼 Foals (Born to Unvaccinated Mares)

• Start as early as **2–4 weeks of age**
• Same 3-dose protocol applies
• Ensure no delay due to lack of maternal antibodies

💉 Administration & Storage

• Administer IM (intramuscularly), typically into the neck
• Use sterile needle/syringe and change needles between horses
• Store refrigerated at 35–45°F (2–7°C); do not freeze ❄️
• Shake well before use; discard after 10 doses or 30 days if multi-dose vial opened

⚠️ Side Effects & Reactions

Most horses tolerate Botvax® B well. Mild signs may include:

• Swelling or soreness at injection site (common)
• Transient fever or depression
• Rare: allergic reactions—treat with antihistamines or epinephrine

🔬 Efficacy & Duration

Protective immunity is achieved after the full 3-dose series. Booster doses maintain efficacy, with annual vaccination recommended for continued protection. Pregnant mares boost foal immunity through colostrum transfer 🛡️.

📍 Who Should Be Vaccinated?

• All foals—especially in endemic areas or high-risk farms
• Broodmares—ensure passive protection for newborns
• Horses fed fermented hay, haylage, or silage
• Horses in Mid-Atlantic states (KY, PA, MD) where Type B botulism is endemic

🚨 Botulism Exposure Risk

Horses can contract botulism by:

• Ingesting spoiled haylage or silage
• Wounds contaminated with soil (rare)
• Foals from unvaccinated mares ingesting spores while nursing or crawling

Symptoms include muscle tremors, progressive weakness, difficulty eating/drinking, recumbency, and respiratory paralysis. Rapid diagnosis and antitoxin treatment is critical—but prevention is far more effective.

📌 Final Takeaways

• Botvax® B protects horses against **Clostridium botulinum type B**, the most common botulism strain in U.S. equines
• Given in a 3-dose initial series, followed by **annual boosters**
• Essential for foals, broodmares, and haylage-fed horses
• Minimal side effects, high safety margin, easy IM injection
• Part of core protocol in endemic regions or high-risk environments

Not sure if your horse needs Botvax® B? Ask A Vet offers 24/7 veterinary consultation for vaccination planning, regional risk review, and annual care advice. Download the Ask A Vet app today and ride with confidence! 🐴💉