Hello Will, yes I heard about it and I think it's certainly a good idea!
This therapy was conceived to treat a variety of diseases like anemia (or blood loss), bone infection, laminitis, connective tissue injuries (torn ligament and bowed tendon), etc.
The air we breathe contains about 21% oxygen, with the remainder made up of nitrogen and tiny amounts of other gases. Red blood cells take up oxygen from the lungs, carrying it in dissolved form to all parts of the body. Breathing more rapidly or deeply does not increase the amount of oxygen carried by the blood, and breathing pure oxygen at normal atmospheric pressure increases it only slightly. However, putting a horse in a hyperbaric chamber and increasing the atmospheric pressure to much greater than normal is very effective in enhancing the oxygen-carrying ability of the blood because oxygen is forced into the plasma in addition to being carried by the red blood cells.