Static magnets are just one of those gimicky things. There's no strong evidence that they actually do anything, despite what companies claim. They've tested it on metacarpals/tarsals (minimal muscle interference ) and there was no significant effect on blood flow. I'd be very shocked if static magnets have any effect on hooves. The science of it is questionable at best, and both as an equine scientist and an animal physio, I would not bother with static magnets.
Anything that claims to reduce inflammation by increasing blood flow is eyebrow raising. Increasing blood flow to inflammation, particularly a recently acquired injury or problem, will make it worse. The aim is to restrict blood flow as the inflammation response is carried through the blood (it's a necessary response but sometimes the body forgets to shut it off in time). Blood flow is then increased after inflammation is under control to remove waste and add healing nutrients. Generally, chronic problems (ones that last long) are treated with both, depending on what is necessary.
PEMF may have an effect but it really depends on the problem and where it is. It should also not be attempted by anyone not trained as there are different settings that do different things, and someone may make it worse.
In short, I would be very very skeptically and would not recommend them unless better, more definite studies come out.
I'm a big fan of magneto-therapy, I use it a lot on my horses! Magnetic therapy has proven effective to speed healing by increasing blood flow, reducing inflammation and easing soreness.
It works with boots, so why not with bell boots?
But as Lauren said, it can't be a unique solution. Hooves have a really complicated and specific structure. I advise you to read this article about it: https://www.equisearch.com/HorseJournal/hooves-resist-magnetic-therapies
They did studies about the effect on magnetic bell boots on horses who had foot pain, and they had disappointing results.
Horses suffering from ring bone saw improvements, but as soon as they took off the boots, the pain increased again.
So maybe in the future, it will have better results 🙂
Hooves are very hard to treat locally, their good health depends on a lot of factors. That's why I think it can't be a unique solution, although it can supplement another treatment. I read that it can help horses suffering from laminitis, navicular, pedal bone fracture, poor hoof growth,...