💉 Vet Guide: Tetanus Antitoxin vs. Toxoid in Horses | 2025 Protection Protocols, Foal Safety & Emergency Use 🐴

By Dr Duncan Houston, BVSc

Tetanus remains one of the most feared—and fatal—diseases in horses. Caused by the bacterium Clostridium tetani, it’s found in soil and feces, and can enter the horse’s body through even the smallest wound. Thankfully, **vaccination is incredibly effective**—but only if used correctly. 🧠🐎

Many horse owners are unaware that there are actually **two different tetanus products**: the **toxoid** and the **antitoxin**. Each serves a different purpose and works on a different timeline. In this 2025 guide, I’ll break down what they do, when to use them, and the risks associated with both. 📋💡

🧪 Tetanus Toxoid: The Yearly Vaccine

Tetanus toxoid is the **standard annual vaccine** given to horses. It trains the immune system to recognize and fight off tetanus by introducing a harmless version of the toxin. ✅

Key Facts:

• 💉 Provides **long-term immunity**—booster needed once per year
• 🕒 Takes about **2 weeks to become effective** after administration
• 📆 Should be part of your horse’s core vaccine protocol

If your horse is up to date on their toxoid, they are well protected—even if an injury occurs. 🛡️

🚨 Tetanus Antitoxin: Emergency Short-Term Protection

Tetanus antitoxin is given when a horse **has not been vaccinated** and suffers a wound or trauma. It provides **immediate, short-term protection** by delivering antibodies that fight off the toxin directly. 🧪⚡

Antitoxin Highlights:

• 🩸 Works **immediately** after injection
• 🕒 Protection lasts about **10 days**
• 📦 Typically used in emergency situations or surgery when toxoid status is unknown

⚠️ Two Important Caveats:

1. 🧬 Serum sickness: Antitoxin has been linked to rare—but serious—allergic reactions. These are more common in **newborn foals** or immunocompromised horses.
2. 📉 It’s not 100% effective: A study from Belgium showed some horses still developed tetanus **despite receiving antitoxin** after injury.

This makes **preventive vaccination with toxoid far more reliable**. 🧠

🍼 Foals and Tetanus Risk

In the past, it was common to give **tetanus antitoxin to newborn foals**, but because of the risk of serum sickness, this practice is no longer recommended. ❌

What to Do Instead:

• 👩‍⚕️ Vaccinate the **mare 4–6 weeks before foaling** with tetanus toxoid
• 🍼 This transfers antibodies to the foal via **colostrum**
• 📋 Foals can then begin their own **toxoid vaccine series around 4–6 months old**

This provides **safe, reliable protection** without the risks associated with antitoxin. 🧬

🧠 Real-World Scenarios: What to Use When

✅ Use Toxoid When:

• 📅 As part of annual core vaccination
• 🍼 Pre-foaling (for passive immunity transfer)
• 📦 In surgical cases if previously vaccinated

🚨 Use Antitoxin When:

• 🩹 Your horse is **unvaccinated and has a wound or surgical procedure**
• 📉 The horse’s vaccine history is unknown and there’s an **urgent risk**

It’s ideal to give both in these emergency cases—**toxoid for long-term, antitoxin for immediate** coverage. 📆💉

📲 Use Ask A Vet to Track Vaccine Plans

The Ask A Vet app helps horse owners manage vaccination records and respond to injuries quickly:

• 📋 Ask whether your horse needs a booster or antitoxin
• 📱 Store vaccine dates and vet visit notes
• 🧠 Get support for foaling season vaccination timelines
• 🩺 Report injuries and ask about risk levels in real time

Vaccine support, always available. 🐴📲

✅ Tetanus Vaccine Protocols for 2025

• 💉 Toxoid: Once yearly, takes 2 weeks to protect
• 🧪 Antitoxin: Immediate but short-lived protection (~10 days)
• 🧬 Antitoxin can cause **serum sickness** in young or compromised horses
• 📉 Belgian study shows antitoxin is **not fully protective** in some cases
• 📱 Use Ask A Vet to manage timing, wounds, and vaccine records

📲 Final Thoughts from Dr Duncan Houston

Tetanus is nearly always fatal in horses—but it’s also **highly preventable**. The best strategy is clear: keep your horse’s toxoid vaccine up to date. Don’t rely on emergency antitoxin, especially with its risks and uncertain protection. Talk to your vet annually, and review your horse’s vaccine status before it’s too late. 🧠💙

Download the Ask A Vet app for up-to-date vaccine support, wound management, and peace of mind in 2025 and beyond. 🐎📱