Just saw this–we have a yearling filly that came in with a cut that severed her hind suspensory. It happened on Christmas Eve of '08. She belongs to a client, who luckily was able to afford to give her every possible treatment known to man, and it’s healed really well. She’s just started handwalking this week (not fun!) and she seems pretty sound.
She had surgery to repair the ligament, and was on IV antibiotics the first week, and actually had a cast on for three weeks. After that she was kept bandaged for another five weeks, and on total stall rest for about three months. She also got stem cell treatments and spent some time in the hyperbaeric chamber. Her prognosis is guarded for racing–it really depends on how much arthritis she develops–but good for less stressful stuff and excellent for being a broodmare.
The original injury was pretty nasty, and the cut went to the bone in a couple of places, but now there’s just a small bump and scab left.
If your horse’s injury has much discharge, it may be a good idea to step up the antibiotics.