So sad for Jimmy...it sounds like the treatment was worse than the bite. Unfortunately, in many instances injury or medical treatment, horses succumb as a result of laminitis and not the original issue. We just had a recent discussion concerning laminitis on the Horse group.
If anyone remembers Barbaro, the 2006 Kentucky Derby winner who broke three bones in the ankle of his back leg in the Preakness , the second leg of the Triple Crown. Chances are he could have made it if it weren't for developing laminitis in his good back leg and eventually both front legs. Laminitis is an anticipated side effect of leg injuries where horses have to bear weight unevenly on their legs for an extended period of time. Barbaro fought a good fight and had the adoration of the nation until he finally had to be euthanized seven months later, due to the complication of laminitis.
Since Jimmy's laminitis sounds like a systemic cause instead of a weight bearing one he may have a better chance of pulling through. although it's certain he will never race.
Oh, and they say Jimmy is a colt, which means he is not a gelding in race terminology, so he could have a long and lucrative career in the breeding shed if he proves to be a prepotent sire. Not a bad life!