Good Morning and welcome to Just answer. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
In most cases, wind puffs are merely a problem of asthetics rather than a medical condition. Since Earl has this in only one fetlock, this swelling may be due to irritation of arthritis in the fetlock joint which would respond to icing after being ridden and hosing this off which massages this fetlock area. Ice compresses causes a reduction in this swelling which will reduce any scar tossue that could develop secondary to this condition. If Earl is not lame, most often bute is not required.
I would recommend having your vet xray Earl's hind fetlock to see if there is arthritis in this joint causing this swelling. If this is present, you will have to manage this since there is no treatment for this.
Sincerely, XXXXX XXXXX