A very special thank you to Dr. Laura Taylor for providing the information woven into this post.

THE HIDDEN DIGESTIVE IMBALANCE

I first learned the term subclinical hindgut acidosis back in 2012, when I took my rescue horse Spirit to see Dr. Laura Taylor, DVM. Spirit wasn’t just uncomfortable — he was in real distress, swinging from sweet to explosive, and no veterinarian could tell me why. That visit was a turning point. It was the first time I understood how hidden digestive imbalances could cause such intense behavioural and physical reactions. (Read A Story with Spirit.)

Since then, I’ve continued to learn about hindgut health — both through study and through experience with my own horses. Subclinical hindgut acidosis is surprisingly common, and often missed.

Simply put, this condition occurs when the pH in the large intestine (the cecum and colon) becomes too acidic. When that happens, the “good” fibre-digesting bacteria start to die off, while the acid-producing bacteria take over. The result? A horse that might not show clear digestive problems, but still isn’t quite right.

WHAT CAUSES SUBCLINICAL HINDGUT ACIDOSIS IN HORSES?

Horses are designed to eat small amounts of forage all day long while moving freely. In modern life, we often feed in larger meals and limit turnout, which changes how the digestive system functions.

If your horse gets concentrated feeds, grain, or lush, sugary grass, undigested starch can end up fermenting in the hindgut. That fermentation lowers the pH, upsetting the balance of healthy microbes. Add in stress — trailering, training, herd changes — and you have a recipe for digestive upset.

HOW TO RECOGNIZE SUBCLINICAL HINDGUT ACIDOSIS (& Why It’s Easy to Miss)

“Subclinical” means below the surface. You might not see strong symptoms, but your horse could still be feeling the effects. As Dr. Laura Taylor, DVM explains, many horses with this imbalance show it through their body and movement, not necessarily their manure.

From an osteopathic perspective*, hindgut acidosis can create restriction patterns in the lumbar spine, sacrum, and pelvis — most often on the right side, where the cecum sits. Horses may feel stiff through the hind end, reluctant to bend, or just not quite engaged behind. These changes often improve or resolve when the underlying gut imbalance is addressed.

You might notice:

A bloated or “hay belly” look
Difficulty bending or engaging the hind end
Mild recurring colic signs (the horse goes ‘off his feed’)
Rings on the hooves or warmth at the coronet bands
A general sense that your horse is “off”
Wood chewing, weaving, and stall walking behaviours

Clinical vs. Subclinical — Why the Difference Matters

It’s helpful to understand what “subclinical” really means. Subclinical* conditions exist below the threshold of clinical detection — there are no obvious symptoms, even though the imbalance is present. Clinical conditions, on the other hand, have clear and identifiable symptoms or signs that can be observed and diagnosed by a healthcare professional.

Because horses can’t tell us what they feel, we rely on observation and performance clues: difficult transitions, sensitivity in the flank area, or behavioural changes.

Recognizing these subtle signs requires a HOLISTIC EYE — one that looks beyond symptoms to the horse’s overall comfort, movement, and expression.

Please note: Dr. Laura Taylor’s osteopathic assessment is the only way to accurately determine whether hindgut acidosis — clinical or subclinical — has fully resolved after treatment and dietary support. Her work makes it possible to evaluate true freedom through the sacrum.

HOW TO SUPPORT AND MANAGE HINDGUT HEALTH NATURALLY

There’s no one-size-fits-all fix, but here’s what I’ve found to make a difference in my herd:

Forage first – Make sure your horse has hay or pasture available as much as possible. We limit pasture intake to the low-sugar times of year and only if the horse’s health, gut, and feet can handle it.
Avoid large grain meals – These can quickly disrupt the hindgut environment.
Feed changes slowly – Allow gut microbes time to adjust.
Encourage movement and turnout – Motion supports digestion and lowers stress.
Provide prebiotics and probiotics – Products like Equine Choice Prebiotic + Probiotic help balance gut flora.
Buffer the hindgut – KER EquiShure supports a more stable pH and a healthier microbial environment.

HELPING HORSES THRIVE THROUGH BETTER HINDGUT HEALTH

As I’ve learned through both study and experience, hindgut acidosis is preventable — but only if we understand what’s really happening inside our horses. Paying attention to forage quality, feeding habits, and stress levels can make all the difference!