Hi Maria,

My personal opinion is that most of these products work by actually drying the hoof out rather than making it tougher.  Lavinia may have a more scientific explanation but I'm not a real fan of any of them.  What I have had good luck with as a sole protector is Hoof Armor, but I'm not sure it is available to you or if would do what you really want.  If you want to inquire there is an EU distributor listed on the website - http://www.hoofarmor.com/

It is painted on the hoof and will wear off eventually but I've used it on my gelding to protect his bare feet when we were doing 75 miles in the sand. I didn't want him to wear his hoof down with that much work in the sand and I also don't like to use boots in the sand so the Hoof Armor was a good compromise.  It did mostly wear off after the 2 days (50 miles the first day and 25 the second) but he didn't lose any hoof.  

HTH, 
Sherry and Scutch (and Scarlet over the bridge)
EC Primary Response 
PA 2014
https://ecir.groups.io/g/CaseHistory/files/Sherry%20and%20Scutch_Scarlet 
https://ecir.groups.io/g/CaseHistory/album?id=78891