Therapy Horse Blankets with Fridge magnets on them?: Static Magnets, Bad Citations & Equine Marketing

🚩🚩🚩 YIKES ON BIKES. Apparently we need to talk about fridge magnets again 😂

I’ve had several people ask me to look into equine “magnetic therapy” products, so I went digging through the science behind the claims. The marketing gets confusing fast because words like magnetic field, electromagnetic therapy, and PEMF get thrown around like they all mean the same thing.

They do not.

My issue is not that a product contains a magnet. Magnets obviously create magnetic fields. My issue is selling a static permanent-magnet product and then using research on pulsed electromagnetic field therapy (PEMF) as evidence for that product.

Those are different technologies with different operating conditions and different physics.

Static magnets and PEMF are not the same thing

A permanent magnet sewn into a blanket or wrap produces an essentially static magnetic field while it sits against the horse.

PEMF equipment deliberately creates a time-varying magnetic field. The field changes as the machine pulses.

That distinction is fundamental electromagnetic physics.

Faraday’s law connects an induced electric field, or electromotive force, to the change in magnetic flux over time. In engineering shorthand, the important term is dΦ/dt. A magnetic field simply existing is a different physical condition from a magnetic field changing with time.

PEMF is not a fridge magnet with better branding. 😂

A static magnetic field can still interact with matter under specific conditions. Very strong static fields are a legitimate area of physics and biomedical research. And I mean SUPER high strength. That still does not make a small permanent magnet sewn into fabric equivalent to an electrically powered pulsed electromagnetic device.

Okay, but what does Faraday’s law actually mean?

Here is the non-physics-degree version.

Imagine a truck parked in your driveway. It is still a truck. It has mass, takes up space, and exists. But if it never moves, it is not transferring momentum down the road.

Now imagine that truck accelerating past you. Same truck. Very different physical situation because something is changing with time.

A permanent magnet sitting in a blanket creates a magnetic field, but that field is basically just sitting there. PEMF intentionally changes the field over and over again.

Faraday’s law is commonly written as ε = −dΦ/dt. Do not panic 😂

ε represents induced electromotive force, and dΦ/dt describes how magnetic flux changes with time. If magnetic flux through a region changes, an electric field can be induced. If the flux through a stationary region is not changing, that Faraday-induction term is zero. This is standard electromagnetic induction physics. (https://openstax.org/books/university-physics-volume-2/pages/13-1-faradays-law)

This is why the word PULSED in Pulsed Electromagnetic Field therapy is not decorative marketing fluff. The pulse is the whole reason the magnetic field is changing.

A fridge magnet: “I’m here.” 🧲

A permanent magnet stuck to your refrigerator creates a static magnetic field. While the magnet and surrounding tissue are stationary relative to each other, that field is not being deliberately switched on and off.

PEMF: “I’m here. I’m gone. I’m here. I’m gone.” ⚡

A PEMF machine sends electric current pulses through a coil. Current creates a magnetic field, and changing current changes that field. That is where Faraday’s law enters the picture.

This is also why PEMF systems have parameters such as frequency, waveform, pulse duration, intensity, coil geometry, and rise time. Those variables describe what the field is doing over time. A permanent magnet does not acquire those properties because somebody sewed it into an expensive blanket.

Wireless charging is an easy example

If a stationary permanent magnet continuously transferred useful electrical energy just by existing, your refrigerator magnets would be charging your phone right now 😂

Wireless charging relies on changing electromagnetic fields to induce voltage in another coil. Generators and transformers depend on the same general principle of changing magnetic flux. I am not saying PEMF is a phone charger. I am using a familiar example of why change matters in electromagnetic induction.

Now for my favorite part: citation games

One magnetic-therapy page I reviewed had a decent sized list of scientific references under claims that magnets stimulate blood flow, improve lymphatic function, increase oxygen in tissues, promote healing, relieve pain, blah blah blah (insert more marketing jargon here).

At first glance, it looks impressive. Journals. Authors. Dates. Science-y words.... Then you actually read the papers.

Several of the references study pulsed electromagnetic fields, not the static permanent magnets being sold in the product.

One citation is an equine study by Kold, Hickman, and Melsen. They studied daily PEMF exposure and bone graft incorporation in eight yearling ponies. (https://pubmed.ncbi.nlm.nih.gov/3552658/)

The article is real. It just does not test a static magnetic blanket. Zero correlation.

Seeing the word “magnetic” in a PEMF paper and citing it for a permanent magnet is like citing a jet-engine paper to prove your ceiling fan produces air thrust.

If I used blatantly inapplicable references in an engineering analysis, that analysis would not survive technical review. And someone could die. Applicability matters. You do not get to swap one technology for another just because the terminology sounds similar and then call it “evidence.” 

A PubMed citation is not a magic spell. The paper has to support the claim and the technology you attached it to.

What happens when researchers actually put static magnets on horses?

This is the best part. Researchers have put commercial static magnetic products on horses and measured the things the marketing says should change.

In one randomized controlled equine study, a commercially available static magnetic wrap was placed on one metacarpus and a control wrap on the other. After 48 hours, the magnetic wrap did not significantly increase blood flow beneath the wrap compared with the control. (https://pubmed.ncbi.nlm.nih.gov/10997160/)

Another prospective, randomized, blinded, placebo-controlled crossover study tested a blanket containing 900-gauss static magnets on ten healthy horses. The researchers measured back-muscle blood flow, skin temperature, mechanical nociceptive threshold, and behavior. The active magnetic blanket produced no significant difference from the placebo blanket in those outcomes. (https://pubmed.ncbi.nlm.nih.gov/24779912/)

Skin temperature increased under both blankets in the blanket study. That is a good reminder that “my horse felt warmer under the magnetic blanket” does not prove the magnets increased circulation.

Sometimes a blanket is just... a blanket. 😂 And the neoprene patches that are sewn over the magnets stop airflow and create warm or sweaty spots does not in any way prove that the magnets did anything. Those sweat spots would be under the neoprene whether a magnet was sewn in or not. 

“But blood has iron in it!” 🩸🧲

Yes. Hemoglobin contains iron.

No. Your horse’s bloodstream is not a bag of roofing nails. 😂

The iron in hemoglobin is chemically bound within the heme structure. Blood is not ferromagnetic, so a magnet does not grab blood and pull it through vessels the way it attracts a steel screw. If that were the case, then MRI machines would suck all your blood out faster than a starving vampire. 

The actual physics is more interesting. Oxygenated hemoglobin is diamagnetic, while deoxygenated hemoglobin is weakly paramagnetic. Those magnetic-susceptibility differences are real and are important in magnetic-resonance physics. (https://pubmed.ncbi.nlm.nih.gov/6591198/)

“Hemoglobin has measurable magnetic properties” and “a permanent magnet sewn into a horse blanket increases circulation” are completely different claims.

The second claim is testable, and researchers tested it in horses. They did not find the advertised increase in blood flow. (https://pubmed.ncbi.nlm.nih.gov/10997160/) (https://pubmed.ncbi.nlm.nih.gov/24779912/)

So I bought a Gauss meter because apparently I needed more hobbies 🧲😂

This started because I kept hearing some version of: “These aren’t fridge magnets. They’re therapeutic magnets. They’re super strong.”

Okay then.

So I did what any totally normal engineer with an unanswered question and an Amazon account would do.

I bought a $40 Gauss meter on Amazon. 😂

I used my own blue meter to test ordinary household magnets, including fridge magnets and chip-clip magnets. I measured 343.7 G, 515.3 G, and one absolute unit of a household magnet at 1449.2 G. 💀🧲

Apparently my kitchen is now a rehabilitation facility.

I also had screenshots from a company video where the company used a different green Gauss meter to compare magnets in several equine magnetic “therapy” products. The readings shown in that video were approximately 382.2 G, 365.3 G, and 230.5 G. Some might argue that the meters are different so it would result in different numbers but both meters have a very high accuracy calibration and magnetism is a physical property that doesn’t change (even if you flip it over, squish it, and bend it in half - the meter will read the same Gauss value).

The useful observation is much simpler: permanent magnets in expensive “therapy” products do not occupy some magical category of physics that ordinary household magnets cannot reach. Household magnets can produce surface field readings in the same general range, and most of my fridge chip-clip magnets measured substantially higher than the values shown in that company’s video.

Gauss measures magnetic flux density. It does not measure healing.

A Gauss meter tells me about the magnetic field at the probe.

It does not tell me whether that magnet increased blood flow, reduced inflammation, accelerated tissue repair, improved lymphatic drainage, or relieved pain.

Those are biological claims. They require biological evidence.

The 900-gauss equine blanket study is a perfect example: the magnets had a stated field strength, but the blanket still did not significantly increase muscle blood flow compared with placebo. (https://pubmed.ncbi.nlm.nih.gov/24779912/)

Gauss is a measurement of magnetic flux density. It is not a measurement of therapeutic efficacy.

But my horse LOVES his magnetic blanket

That is completely fine.

If your horse relaxes in a certain blanket, wrap, boot, massage routine, grooming routine, or whatever else you use, great. I am not coming to your barn to confiscate it 😂

Just separate the observation from the mechanism. “My horse seems to like this blanket” is not the same claim as “the static magnets increased circulation, oxygen delivery, lymphatic drainage, or tissue healing.”

Rest, warmth, compression, handling, natural recovery, changes in workload, and our own expectations can all influence what we observe.

That is why blinded placebo-controlled studies exist.

How I check “science-backed” marketing

• Did the study test the same technology? Static magnet ≠ PEMF.
• Did it test the same species and target tissue? A bone experiment does not automatically prove a circulation claim in an equine leg.
• Were the physical parameters comparable? Field strength, waveform, frequency, exposure time, geometry, and distance matter.
• Was there a sham or placebo control? Especially when the outcome includes pain, relaxation, or behavior.
• Does the paper’s conclusion actually support the marketing claim? Read the methods and conclusion, not just the title.

Having citations and having applicable citations are two very different things.

The engineering takeaway

If you like a magnetic blanket because it is a nice blanket and you spent a lot of money on it, use the blanket. Or sell it and get some of your money back.

If someone wants to charge therapeutic-equipment money because permanent magnets are sewn into it, I want the evidence to refer to those magnets, not a completely different electrically powered PEMF machine.

If the claim is increased circulation, show me the blood-flow data.

If the claim is that stronger Gauss means more healing, show me the dose-response data.

If the claim is that a static magnet is basically PEMF, please revisit Faraday’s law. 😂

Horse owners have plenty of legitimate therapies to spend money on. We should be able to ask what a product physically does, what was actually tested, and whether the cited paper applies to the product being sold.

Spend your money on whatever you want. I just want people to know whether they are buying a claim that has actually been tested - or if they are being bamboozled by sketchy marketing.

And no, putting a scientific citation next to a fridge magnet does not turn it into PEMF. 😂🧲

This article discusses the physics and published evidence surrounding static magnetic and pulsed electromagnetic products. It is educational information and is not a substitute for veterinary diagnosis or treatment.