I know that many people, myself included, have used Voltaren on their horses. However, with changes in federal law about getting medicine across borders this has proven to be quite difficult.
Even though you can get Voltaren in a Canadian Walgreens you can’t get it or the horse version Surpass without a prescription.
I stumbled across this today, sounds an awful lot like the same thing. Pricey though and can’t find an ingredient list.
https://www.bigdweb.com/product/excellr8+topical+cream+4+oz.do?ecList=&ecCategory=