1. Understand the Stressors

Late summer creates a perfect storm for digestive sensitivity. Common stressors include:

• • • Heat stress reducing appetite and slowing gut motility
    • Travel and show season elevating stress hormones
    • Pasture decline as grass dries and loses digestible fiber
    • Hay variability as barns switch to new lots or suppliers
    • Hydration inconsistency because horses drink less in heat

All of these impact the hindgut, where fiber fermentation and microbial balance occur.

Why it matters:

When hindgut microbes become unstable, horses may show:

• • • Loose manure
    • Gas
    • Mild colic
    • Irritability
    • Reduced appetite
    • Girthiness
    • Performance decline

A reset helps stabilize the system before fall transitions begin.

2. Reinforce Hydration

Hydration is the foundation of hindgut stability — and late summer is when horses are most at risk.

Why horses drink less in late summer:

• • • Stress reduces thirst cues
    • Horses sweat more but don’t drink enough to replace losses
    • Some horses avoid warm water, troughs or buckets

What barns should do:

• • • Offer multiple water sources
    • Add electrolytes during heat waves
    • Keep buckets clean and cool
    • Monitor intake, especially for seniors
    • Use free-choice salt to encourage drinking
    • Fiber intake also helps encourage water intake

Hydration drives fiber fermentation and reduces colic risk.

3. Stabilize Forage Intake

Late summer forage is inconsistent — and sudden changes disrupt hindgut microbes.

Common late‑summer forage issues:

• • • Pasture fiber increases but palatability may change
    • NSC (sugar) fluctuates
    • Hay quality varies between loads
    • Horses switch from pasture → hay more often

4. Support Hindgut Fermentation

Late‑summer stress reduces microbial efficiency. Horses may struggle to ferment fiber properly, leading to:

• • • Reduced nutrient absorption
    • Lower energy
    • Poor coat quality
    • Mood changes
    • Digestive sensitivity

What helps:

Add digestible fiber sources:

• • • Beet pulp
    • Soy hulls
    • Senior feeds
    • High‑quality forage pellets

And consider targeted digestive support:

• • • Yeast cultures
    • Prebiotics
    • Hindgut buffers

These stabilize microbial balance and support consistent digestion.

5. Prepare for Fall

Fall routines are coming soon — and it’s often different from summer feeding routines.

Why fall transitions are harder when the gut is unstable:

• • • Digestible fiber may change
    • NSC may spike due to cooler nights
    • Pasture availability drops
    • Horses shift to hay‑only diets
    • Seniors struggle with fiber changes

A stable gut now = smoother fall transition.

What barns should do in August:

• • • Reinforce hydration
    • Stabilize forage
    • Support hindgut microbes
    • Monitor manure
    • Monitor Weight and Body Condition
    • Prepare seniors early

This sets horses up for success when fall forage arrives.

Final Takeaway

Late summer is the “gut wobble” season — a time when horses are more sensitive to stress, forage changes, and hydration swings. A simple gut‑health reset now helps prevent fall digestive issues, weight loss, and senior decline.

A proactive approach in August leads to a smoother, healthier transition into fall.

-Dr. Stephen Duren  M.S. PAS Ph.D. Equine Nutrition and Exercise Physiology, Performance Horse Nutrition

-Dr. Tania Cubitt  Ph.D. Equine Nutrition and Reproduction, Performance Horse Nutrition