i've used equine america cortaflex which is very good, also as a cheaper option but also good is the EA Glucosamine, i'd probs try the Glucosamine first
I have posted this about 15 times but i can assure you i dont work for them.
My mare has blue chip dynamic feed and it is really really good it is for joints and the £40 bag lasts my 16.2 about 6 weeks. Not the cheapest but it is a feed not a supplement.
I could tell within the first 3 weeks i tried to take her off it for the summer but could really tell the difference so i have put her back on it. She is 18 years old and has arthritis but you would never know when she is on this stuff, it is that good.
No lameness at all, in at night out during the day, clicks when in, sure it is nothing to worry about, just thought I would give him something to help him along.