LubriSyn or Hyalauronix, both top dressed HA gel starting when it first became available, 2004 or 5. I used it for 5 or 6 years, was able to get off the monthly IV Legend (HA) shots and drop the IA joint injections of HA to once a year… None of the rest of the less pricey orals available at that time had much, or any, noticeable effect.
I discontinued it because it no longer was having any effect on 20 year old joints. On the plus side, HA is now the go to choice in skin care products so we were way ahead of the times with the best looking skin and nails in any barn. I took a teaspoon a day for my 50 year old knees and other joints. Worked noticeably, didn’t sound like a popcorn machine coming down the stairs.
Not understanding why any of these products would be contraindicated in IR or previously foundered horses? Many put those on HA. Helps most of them move easier. Not all though, no magic bullet for age related deterioration of joints. Whole lot of BS out there too.