It sounds like Stocking up to me, usually brought on by lack of excercise..
I am posting an article, Hopefull this wil help...:
Stocking up is associated with stall confinement, lack of exercise and overfeeding, specifically grain. Certain horses are predisposed to stock up, others next door are fine. Once turned out for exercise, the swelling usually disappears. The plain and simple cure for stocking up is more, regularexercise. This does not mean harder or longer rides when you do ride but more opportunities for the horse to get exercise during the day, every day. Many horses do not do well in stalls full time.
It takes a lot of time, supplies, bandage washing, and expertise to apply and monitor standing bandages. If that's the way you want to go, be sure to get competent coaching. Generally a horse's legs will tend to become dependent on the regimen. So for a chronic problem, do you want to commit to a lifetime of standing wraps? When applied correctly, standing wraps can result in reduced swelling. But if done incorrectly, they could result in tendon problems (from uneven pressure or abrasion), stall kicking (if bandages are uncomfortable or slip) etc.
There is no need to use sport boots, because when you ride the stocking up problem is eliminated. I've seen many problems occur with improperly applied sports boots. Also neoprene concentrates heat against the skin - stocked up legs are already swollen and warm so you don't want to enclose and exacerbate the effect of the heat.
Generally you don't want to increase heat to an area of swelling and since liniment increases heat to the skin superficially, it is not a good idea.
Running cold water on stocked up legs is the best advice you received and will do the most good, next to providing regular exercise.
Hosing with cold water either before or after a ride would be ok. The thinking is, before a ride reduces the swelling the horse has when you take him out of the stall.
Hosing after a ride: when the swelling has disappeared from exercise but his legs are warm, if you run cold water on his legs before you put him away, it usually tends to decrease the tendency for fluids to pool in his legs as would happen if you "put him away warm".
If you choose to hose your horse's legs with cold water after each ride, however, realize that just a few minutes won't do any good - you need to do about 10-15. And daily periods of wetting his skin, hair and hooves can invite lots of new problems - like skin fungus or a weakening of the hooves from repeatedly wetting and drying. Horses hooves are best when strong and hard, not soft and wet. If you hose, be sure you dry the horse's legs and hooves very thoroughly before you put him back into the stall.
Bute is an anti-inflammatory drug that is good for reducing swelling but if this is a chronic condition, you can't put the horse on bute for life, so don't consider it at this point.
X-rays are not something that would even cross my mind for stocking up.
Although I have shared my opinions with you, as you have found out you can get as many opinions as people you ask! My disadvantage is not being able to see the horse, facilities, management, and his conformation and work in person. Ultimately you and your vet will have to sort out what sounds the most logical to you since you know the horse, his environment, and your own situation the best.
In summary, the number one "cure" is to provide more regular exercise. If your horse could live in a turn-out pen with a roof at one end for shelter from sun, rain, etc. He might never stock up. Do you have that sort of facility available? Some stables include turn out (1-2 hours per day) as part of board and that might be enough exercise. But standing for 22 hours or more per day in a stall just allows the fluids to pool in the lower extremities and certain horses just aren't equipped with the internal physical apparatus to pump the fluids out of the tissues without exercise.
As far as therapy, cold water hosing is my pick. It’s a good idea whenever you’re treating horses to always start conservatively.
While that's a good assumption, it's not the case with my two. I have dealt with stocking up back when I had to board and a different horse had a cement stall.
My horses don't get grain, they have 22 acres of hills they cover nearly every day (water is only at the barn so they have to move to come up for water), both horses came in from the pasture a stubby mess, and the big Walker has the run-in stall that is attached to the 24 X 100 paddock, so he can come and go as he pleases to eat grass in paddock all night.
Pastures have been bushogged four times already with #5 coming before we're too far into Fall, so if they are getting into toxic weeds, I would think at least two legs would be affected instead of one on each horse
Both horses have bumps on their legs that look like massive outbreaks of poison something-or-other. Reminds me of a big fat outbreak of poison sumac I once got. That's why my vet thinks either ants or some kind of ground mites that have been busier than usual due to our extreme weather conditions.
My other two horses don't eat in quite the same areas as these two and they are fine. They all migrate to a general area together but, I notice these two go into certain places of that area, the other two won't.
The Arab is 8 days into his outbreak - the ankle is just a tch swollen (which is less than a tad:), the heat is gone, the hair is tufted where every bump used to be but the skin is flaking off as opposed to peeling back and oozing like scratches would do. He is not losing his hair, it's just tufted from the bumps.
The Walker is 6 days into his outbreak. He is following the same pattern as the Arab, meaning his ankle swelling has gone down but The Man on The Galloping Horse" could still see that ankle is puffed up. He still has quite a bit of heat in the ankle. However, it no longer "rolls over" the front of the joint from being double the size it started out.
He also has the bumps on top of bumps and tufted hair where the bumps are drying up. No oozing on him on that leg. He does have a minor case of "real" scratches on his white fetlock joint on the other rear leg.
That's the other thing, it's the dark legs on both horses - not a piece of white hair to be found.
While I could see this might interpretted as Stocking up, it isn't because they came in the from the pasture looking like this. I check my horses every single night when they come in and again, in the morning, before turnout.