See, that’s one of those hoof supplements with negligible amounts of the relevant nutrients. I like Omniety from Mad Barn, in Canada, but there are American VMS that are very similar. Way more copper zinc and biotin than any hoof supplement. Also decent vitamin E but some prefer more. It’s also got all the chromium and magnesium you need.
You can look up Pete Ramey on best practices in barefoot hoof care. Barefoot folks need to think about hoof nutrition because they don’t have shoes to mitigate issues. You might also find the feeding instructions for metabolic horses interesting, not just NSC feed but larger doses of zinc and copper.
None of this is a quick fix, but it might help build more resistance to inflammation over time
I would suggest trying to give vaxx individually rather than one combo dose. And I actually stopped giving my mare the flu rhino combo because she got NQR for a solid week after. She gets tetanus, West Nile, and I think it’s encephalitis as recommended for our region. We have not had any significant respiratiory issues since I stopped the flu/rhino.