Forage Matters: Soaking Hay - When Does It Make Sense?

This article, written by equine nutritionists Dr. Tania Cubitt and Dr. Stephen Duren of Performance Horse Nutrition, explains when soaking hay is beneficial, when it isn’t necessary, and how soaking affects sugar levels, dust, and nutrient loss. The full scientific article is provided below exactly as originally authored.

Key Takeaways

• Hay soaking may reduce watersoluble carbohydrates (WSC), but results vary widely.
• Soaking can help dustsensitive or respiratory horses.
• Soaking is not a substitute for hay testing.
• Longer soak times increase nutrient loss and spoilage risk.
• Soaking removes minerals like potassium, sodium, magnesium, and phosphorus.
• Steaming is better for respiratory support; soaking is better for metabolic management.
• Not all horses need soaked hay — especially those with normal metabolic function and tested lowNSC forage.

Written by:

Dr. Tania Cubitt, PhD – Equine Nutritionist

Dr. Stephen Duren, PhD – Equine Nutritionist

Forage Matters: Soaking Hay — When Does It Make Sense?

Dr Tania Cubitt & Dr Stephen Duren – Performance Horse Nutrition

Hay soaking has become increasingly common in the horse industry, especially among owners managing:

• Metabolic horses
• Laminitis risk
• Insulin resistance
• Dust-sensitive horses
• Horses with respiratory concerns

But soaking hay is not always necessary — and in some cases, it may create new nutritional challenges if done incorrectly.

So, when does soaking hay actually make sense?

And when might it not be needed?

Let’s take a closer look.

Why Do Horse Owners Soak Hay?

There are two primary reasons horse owners soak hay:

1. To Reduce Sugar Content

Owners managing:

• Equine Metabolic Syndrome (EMS)
• Insulin resistance
• PPID (Cushing’s disease)
• Laminitis

often soak hay in an attempt to lower water-soluble carbohydrates (WSC), including sugars.

2. To Reduce Dust

Soaking can also help reduce airborne dust and mold particles for horses with:

• Heaves
• Equine asthma
• Respiratory sensitivity

In these horses, adding moisture to hay may improve airway comfort.

Can Soaking Hay Reduce Sugar?

Yes — sometimes.

Water-soluble sugars can leach from hay into the soaking water.

Research has shown soaking may reduce:

• Water-soluble carbohydrates (WSC)
• Some simple sugars

However:

The amount removed is highly variable.

Sugar reduction depends on:

• Hay type
• Water temperature
• Soaking duration
• Initial sugar content
• Hay maturity

Some hays show significant reductions.
Others show minimal change.

This is why soaking is not a substitute for forage testing.

The Best First Step Is Still Testing Hay

Many owners automatically soak hay without knowing:

• The original NSC level
• Whether soaking is even necessary

In some cases:

• A properly tested lower-NSC hay may not require soaking at all

And in other cases:

• Hay may remain too high in sugar even after soaking

The safest approach is:

Test first, then decide whether soaking is needed.

How Long Should Hay Be Soaked?

This is where things get tricky.

Longer soaking times may remove more sugars — but they may also:

• Increase nutrient loss
• Reduce palatability
• Encourage bacterial growth in warm weather

Many nutritionists use:

• Shorter soak times in warmer temperatures
• Moderate soaking protocols rather than excessive soaking

Very long soaking periods can create:

• Fermentation
• Spoilage
• Unpleasant odor
• Reduced forage quality

Especially during summer months.

What Nutrients Are Lost During Soaking?

Soaking does not selectively remove only sugar.

It may also reduce:

• Potassium
• Sodium
• Magnesium
• Phosphorus
• Other water-soluble nutrients

This can become important in horses receiving soaked hay long-term.

Over time, diets may require:

• Mineral balancing
• Electrolyte adjustments
• Supplement support

When Soaking Hay Often Makes Sense

Hay soaking may be beneficial for:

• Horses with severe insulin dysregulation
• Horses recovering from laminitis
• Horses with respiratory sensitivity
• Horses consuming hay known to be moderately elevated in WSC

In some cases, soaking can be a practical management tool while owners work toward sourcing more appropriate forage.

When Soaking May Not Be Necessary

Not every horse needs-soaked hay.

If a horse has:

• Normal metabolic function
• Appropriate body condition
• Access to tested lower-NSC forage
• No respiratory concerns

then soaking may offer little additional benefit.

And for some horses, excessive soaking may unnecessarily reduce valuable nutrients.

What About Steaming Hay?

Hay steaming has also become popular, especially for respiratory horses.

Unlike soaking, steaming primarily targets:

• Dust
• Mold spores
• Air quality

Steaming generally does not reduce sugar content significantly.

For some horses:

• Steaming may be preferable for respiratory support
  while
• Soaking may be more useful for metabolic management

Practical Tips for Soaking Hay

If soaking hay:

• Use clean water
• Discard soak water after use
• Avoid prolonged soaking in hot weather
• Feed soaked hay promptly
• Monitor body condition and overall diet balance

And most importantly:

Continue working with your veterinarian or equine nutritionist to evaluate the entire feeding program.

The Bottom Line

Soaking hay can be a useful management tool — but it is not automatically necessary for every horse.

It may help:

• Reduce water-soluble sugars
• Lower dust exposure
• Support certain metabolic or respiratory horses

But soaking also changes the nutritional profile of hay and should be used thoughtfully.

The best forage decisions are based on:

• Hay analysis
• Individual horse needs
• Overall diet balance
• Practical long-term management

Because when it comes to feeding horses:

Forage matters — and understanding the “why” behind management decisions matters too.

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FAQs - by Blue Mountain Hay 

Does soaking hay reduce sugar? 

Sometimes. Sugar reduction varies based on hay type, maturity, water temperature, and soak duration.

How long should hay be soaked?

Shorter soak times are often recommended, especially in warm weather, to avoid nutrient loss and spoilage.

Does soaking hay remove important nutrients?

Yes. Minerals like potassium, sodium, magnesium, and phosphorus can leach out.

Is soaking hay necessary for every horse?

No. Horses with normal metabolic function and tested lowNSC hay often do not need soaked forage.

Is steaming hay better than soaking?

Steaming is better for dust and respiratory issues. Soaking is better for reducing WSC for metabolic horses.

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