You could try Pentosan injections- they are about $200 for a years worth or so... Similar to adequan without the high cost. Get a script sent to wedgewood pharmacy.
Often older horses have arthritis everywhere, so you might as well try something systematic. I never did have luck with glucosamine.
There is an alternative to bute- equioxx (firocoxib). It does not cause ulcers like bute does. Previcox is the dog version and is cheaper. My old mare has arthritis and DSLD in her hind legs. Eventually I will switch her to Previcox, but for now she does well on bute as needed.
"Legally, vets are not supposed to prescribe Previcox for horses, as there is an equine approved form on the market. Unfortunately, Equioxx, the equine alternative, is about 5x as expensive and is a paste, and tends to have much more wastage. A monthly supply of Equioxx is $294, while a monthly supply of Previcox is $55.
Please also note that Previcox is an anomaly in that the dosage for horses is MUCH smaller than that for dogs (my 950 lb horse gets a 57mg dose daily, which I believe is the dosage for a small dog. You should also be warned that if you use Previcox in a horse, you are considered to be using it "off-label," so should your horse react to it, you will have no recourse with the manufacturer. "