🐴 Estrous Cycle Control in Mares: Options for Behavior & Performance Management in 2025 💉🧬

By Dr Duncan Houston BVSc

When mares are in heat, performance and behavior can change dramatically—leading to frustration for riders, trainers, and veterinarians. In 2025, science offers several methods to safely suppress or manage the estrous cycle so mares can stay focused and comfortable. 🧠🐎

🔥 Why Control Estrus?

During estrus (heat), mares may display:

• 🌀 Tail swishing and restlessness
• 🐴 Frequent urination
• 😠 Aggression or reactivity under saddle
• 📉 Decreased work ethic or concentration

Whether the behaviors are physical, hormonal, or perceived by the rider, managing estrus can help improve performance outcomes and safety. 🏇

💊 Option 1: Daily Progesterone (Regu-Mate)

• ✅ FDA-approved and widely used
• 📅 Must be given once daily by mouth
• ⚠️ Absorbs through human skin—gloves required
• 💲 Effective but expensive long-term

Regu-Mate works by mimicking pregnancy hormones to suppress ovulation and behavior. 🧬

💉 Option 2: Compounded Injectable Progesterone

• 📆 Administered as a monthly injection
• 🧪 Less handling compared to daily oral meds
• ⚠️ Not FDA-approved—efficacy can vary by pharmacy

This option offers convenience but should only be used under veterinary guidance. 🧠

🔵 Option 3: Glass Ball Insertion

A 35 mm sterile glass ball or marble is placed into the uterus to simulate pregnancy:

• ✅ Effective in some mares
• ❌ Ball can break or be expelled
• 🧪 Must be monitored via rectal ultrasound

This method has become less common due to complications and inconsistency. ⚠️

💉 Option 4: Oxytocin Injections

Oxytocin is a game-changing option for estrous suppression:

• 🧬 Given once daily on days 7–14 after ovulation
• 🧠 Prevents corpus luteum breakdown—keeps mare out of heat
• 💲 Inexpensive and effective

📅 Dosage Options:

• 💉 60 IU oxytocin intramuscularly once per day
• 🕒 Previously done twice per day—once daily now shown to be just as effective

⚠️ Important:

• 📋 Must track ovulation with ultrasound to time the first dose accurately

This method is a low-cost alternative with minimal side effects, ideal for many performance mares. 📈

🧠 Choosing the Right Approach

Your choice depends on:

• 🎯 Performance schedule
• 💵 Budget and handling ease
• 📈 Severity of estrus-related behaviors
• ⚠️ Mare’s sensitivity to hormones or foreign objects

📲 Ask A Vet for Estrus Suppression Planning

Need help managing your mare’s estrous cycle? Visit AskAVet.com or use the Ask A Vet App to get personalized hormone therapy schedules, ultrasound timing, and safe medication recommendations. 📱🐴

Dr Duncan Houston and the team can help tailor a plan that balances behavior, performance, and long-term health. 💬🧠

🏁 Final Thoughts

Estrous cycle control in mares is more than just managing behavior—it’s about optimizing comfort, focus, and health. In 2025, options like oxytocin provide affordable, science-backed alternatives that can make a world of difference for you and your horse. 🧬🐎

Need cycle control support? Visit AskAVet.com for safe and effective solutions 🐴💉