Ok, as someone who has horses and cleaning up hooves is more or less "ordre du jour" I use the following:
* mechanical cleaning - hoof pick, hoof knife, rasp, hand wire-brush* - daily or every second day. Just keep situational awareness of their feet. Sometimes just picking their feet up is enough.
* 6% oxygen peroxide in a syringe - drip and wash all nooks and crannies in the hoof and frog until it mostly stops foaming. Careful getting sprayed in the face or eyes. This step is important as it cleans and kills most of the anaerobic bacteria and leaves no residue.
* povidone iodine is good, but iodine tincture (~70% ethanol solution of iodine) is a lot better especially when you have a very muddy patch because it does soak in the hoof tissue, but it also stings like buggery, so don't be surprised your horse will pull their foot if you dab over a graze/cut. Apply with a different syringe, same eye precautions apply. You may want to wear nitrile gloves if you don't want to sport a pair of bright brown hands for a few hours.
* further clean as much as possible without making them bigger/deeper all cracks you may find along the white line/hoof wall - remove all clay, sand, mud, dirt, may need to use a small thin flat-head screwdriver to dig stuff out.
* rinse again with peroxide and apply iodine
* pack hoof cracks with cotton wool so that mud and dirt doesn't keep delaminating the hoof. Packing has to be fairly tight, so that it doesn't come out on its own, but doesn't cause delamination. Call it "finger/hand tight" not "weight of a man tight". I use the small screwdriver to pack strands of cotton wool when needed.
* if the weather is particularly shitty, squirt a bit of iodine on the cotton wool and let it soak in.
And finally:
* apply Stockholm Tar fairly liberally with a brush. Get it in all the crevices, over the packed cotton wool, cover the frog and sole, and go up all the way to the coronet band. Wear gloves, this stuff stains and you'll need to wipe your hands with turps to get it off. Don't get it on your clothes either.
Most of the tar on the sole will wash/rub off in the next hour, but the important bits will have gotten into the cracks.
For better bang, you may want to do this in the evening if the horses are sleeping in a dry place over night.
Repeat every second or third day until cracks and smell and weather have righted. In the interim clean dirt, apply a thin layer of Stockholm tar if really necessary.
More advanced approaches involve usage of a mixture of copper sulphate and Vaseline. This nuclear option works, but be aware that it does create a highly acidic environment where applied and I had a chap with thin hooves react to the treatment so much so that I had to wash it all up and go with the approach above this.
(long story short, copper sulphate when dissolved in water will dissociate in a bunch of ions and the solution will very much resemble sulphuric acid - not incredibly concentrated but enough to sting and burn. To be used very carefully.)
(Edit)
I am not claiming it's a silver bullet. As much as anything, it's a combination of cost-effective fixes and good ol' cleanliness. Has worked for us for the past 20+ years.
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*) use the wire brush *only* in a tie-bay or a cleaning area! Do not use a wirebrush in their stall or where they eat, in the paddocks.
The brush will, over time, start shedding the wire bristles. You don't want sharp pins scattered anywhere near them. Also, use a steel/ferrous brush so that you can use a magnet to clean up fallen bristles. Stainless steel does not stick to magnets, neither does brass.