In December 2010 my horse was diagnosed with big head disease. Large facial swellings appeared within weeks, she was reluctant to go forward, dull-coated and deeply depressed, with a short, choppy canter. Looking back, the early signs — depression, intermittent lameness, reluctance to move forward, dull coat — had actually started twelve months earlier, but I didn't recognise them.
This was a shock, as I'd always fed DCP, quality vitamin supplements and lots of Lucerne, believing that prevented big head disease. It didn't. My horses grazed almost 100% Seteria grass, which is extremely high in oxalates and rapidly depletes calcium. Blood tests and x-rays confirmed the diagnosis; my other horses showed milder signs too.
I doubled the dose of highly absorbable calcium/magnesium (XtraCal.au) for eighteen months, switched entirely to grassy hay, and added daily salt, a quality vitamin and mineral supplement, a toxin binder and extra magnesium. By May 2011, follow-up x-rays showed the swelling completely cleared, and my once-depressed, short-stepping mare was forward-going, happy and sound again.
Big head disease is preventable and curable, if you're dedicated and know how.