🐴 Digestion in Foals: Understanding Gut Development from Birth to Weaning in 2025 🍼🔬

By Dr Duncan Houston BVSc

The digestive system of a newborn foal changes dramatically in the first few months of life. In 2025, we now understand more than ever how colostrum, milk, and microbial colonization shape the early health and nutrition of foals. 🧠🐎

🍼 Colostrum: The First and Most Important Meal

The foal’s digestive journey begins with colostrum—the mare’s first milk rich in protective antibodies (immunoglobulins). These antibodies provide essential passive immunity during the first weeks of life. ⏱️

⏳ Absorption Timeline:

• ⏱️ First 6 hours: highest antibody absorption
• 🕒 6–12 hours: decreasing efficiency
• 🚫 After 24 hours: gut closes to antibody absorption

That’s why it’s critical to ensure timely nursing and IgG testing at 12–18 hours after birth. 🧪

🧬 Digestive Development in the First 2 Weeks

In the first 2 weeks, the foal’s digestive tract is geared toward milk. Although foals may nibble hay or grass early, milk is their main nutrient source:

• 🥛 Milk: easy to digest, rich in fat, protein, and lactose
• 🥬 Grass or hay: largely unused until later

Tip: Don’t rush supplemental feeds—young foals don’t yet have the enzymes or microbes to digest them effectively. ⚠️

🔄 Hindgut Maturation Begins at 2 Months

Starting around 2 months, the foal’s hindgut begins maturing. This process allows foals to transition to a forage-based diet by 6 months. Key events include:

• 🦠 Colonization of the hindgut with bacteria
• 🥄 Ingestion of microbes from the mare’s udder and manure
• 🍃 Gradual increase in forage digestion capacity

This microbial population enables hindgut fermentation, allowing nutrients to be extracted from grass, hay, and fiber. 🌾

💩 Foal Heat Diarrhea: What It Really Means

At ~10 days of age, many foals develop soft, non-painful diarrhea. This is commonly known as foal heat diarrhea—but the name is misleading. ❌

Truth: It is not caused by the mare’s heat cycle, but rather by microbial changes in the foal’s gut as it adapts to new bacteria and dietary nibbles. 🦠

Signs of Normal Foal Heat Diarrhea:

• 💩 Mild, soft stool
• 🐴 Bright, alert foal with normal appetite
• 🌡️ No fever or systemic signs

If the foal is otherwise healthy, this condition is normal and self-limiting. ✅

⚠️ Watch for True Digestive Disease

Not all diarrhea in foals is benign. Seek vet attention if you observe:

• 📈 Fever
• 🚫 Refusal to nurse
• 💤 Lethargy or weakness
• 🌡️ Signs of colic or dehydration

Foals can pick up infectious bacteria during early microbial colonization—so hygiene and observation are vital. 🧼🩺

📲 Ask A Vet for Foal Gut Support

Want to optimize your foal’s nutrition and monitor their gut development? Visit AskAVet.com or use the Ask A Vet App for new foal checkups, IgG testing, and gut health supplements. 📱🐴

Dr Duncan Houston and the team can guide you through colostrum timing, early nutrition, and how to safely support a maturing digestive tract. 💬🧠

🏁 Final Thoughts

In 2025, we now know that colostrum timing, milk-based nutrition, and microbial colonization are vital to healthy foal digestion. Understand what’s normal—and what’s not—so you can support your young horse from day one. 🐣🐎

Need a foal digestion timeline? Visit AskAVet.com to download yours 🍼🐴