If you’re here because someone mentioned PSSM2 or MIM and your brain is quietly melting… you're not alone.

Polysaccharide Storage Myopathy (PSSM) is one of the most confusing muscle-related conditions in the equine world — and it’s not getting simpler anytime soon. The good news? You don’t need a definitive label to start helping your horse. You just need clarity, clean support, and a calm place to start.

Let’s break it down.

What is PSSM2?

Short version: PSSM2 isn’t one thing.
It’s an umbrella term for a group of muscle issues where horses show similar symptoms (tightness, stiffness, fatigue, muscle wasting), but test negative for the PSSM1 gene.

You might also hear it called MIM (Muscle Integrity Myopathy) — especially in German-speaking regions — but that’s just a new name for the same mystery.

Is PSSM2 a real condition?

Yes — but not in the “one gene, one test, one fix” kind of way.
PSSM2 can include:

• Muscle fibre damage
• Delayed recovery after exercise
• Overreaction to sugars
• Tension and cramping
• Possibly even issues with calcium handling

And here’s the big one: no single genetic cause has been proven. Despite what some test providers claim, studies by top equine researchers (like Prof. Stephanie Valberg) show that these genetic variants don’t correlate with actual disease.

• Healthy horses can test “positive.”
• Affected horses can test “negative.”
• Muscle biopsy remains the only reliable diagnostic tool — and even that has limitations.

So if the science can’t give us clear answers… what can?

What actually helps?

Simple, targeted, consistent management. Here’s what’s been shown to work - and what we’ve seen transform horses time and again.

Feed the fibre

• Low-sugar hay (<10%, ideally <6%)
• No cereals, no molasses, no high-fat mueslis
• Fibre-based protein (e.g. sainfoin) only if needed
• A balanced mineral supplement (selenium, Vit E, magnesium, zinc, etc.)

Some horses may need support with gut inflammation too — especially if you’re seeing digestive sensitivity or tension around the girth or lumbar area.

Move the muscles

PSSM horses often look lazy - but they’re just tight, sore, or confused by the signals their bodies are giving them. What they really need is daily, consistent movement.

• Aim for sweat-inducing work (ridden or in-hand)
• Avoid long rest periods with rich feeding
• Be patient — reconditioning a sore horse takes time
• Some horses (especially MFM types) may need a more tailored training plan

Support the cells

This is where PSSMFlex was born - to gently support the muscle cells in doing their job.

What’s inside:

• Cramp Bark – for muscle calm and spasm support
• L-Glutamine – to fuel and repair tired muscles
• Acetyl L-Carnitine – to help the muscles convert fat to energy inside the mitochondria

No fillers. No fluff. Just functional plant and amino acid support, the EquiNatural way.

You don’t need a label to take action

That’s the takeaway. You don’t need to wait for a genetic result, a referral, or a muscle biopsy to support your horse with:

• A clean, forage-led diet
• Daily movement
• Gentle, targeted muscle support

Over 80% of warmbloods with suspected PSSM2 see improvement with these basics alone. And if your horse has already been diagnosed with a variant? The same principles apply - minus the panic.

Where to next?

• Explore PSSMFlex – our herbal + amino muscle support blend
• Visit our full PSSM Advice Page – with client stories, feeding tips, and in-depth support
• Have questions? Just get in touch. We’re here to help you and your horse figure it out together.