My mare has minor hock arthritis. She stays happy and sound with injections ~1x/6 months. Lower joints only. She also has mild navicular changes that manifested as 2/5 lameness bilaterally in her front feet last October. Our most serious plan of attack to help her has been corrective shoeing and a change in farriers that has worked wonders. We also put her on previcox (a tiny dose - initially 28.5mg daily, then 28.5 mg every second day) to help with the inflammation, and she has been sound since November. She had a round of Osphos in July, and is now officially off previcox looking better than ever. I’ll be getting new x-rays of her hocks this fall to see where the joint is at - she’s been very happy and I suspect the lower joints may be fused now, in which case - no more injections!
So, to me, judiciously using medications to help a horse remain comfortable for riding is a positive thing. It must always be used in tandem with good judgement about the horse’s level of activity and actual comfort/happiness. I would not be comfortable, for example, riding/exercising a horse who needs 2g of bute to w/t/c and is otherwise 3 legged lame.
Pain meds, like previcox/equiox/bute etc also come with their own side effects and risks, so if you’re looking at a long term maintenance program, that always has to be kept in mind and worked with. My mare tolerated a fairly long course of previcox quite well, but I noticed a difference when we took her off to administer to Osphos, and I noticed the same positive difference now that she is off (hopefully) permanently.
It’s a balancing act, and I think you have to use an equal mix of gut feeling and objective data (hopefully your vet can help with the objectivity piece :))
good luck! I hope your guy comes sound and you are able to find a program that works for him.