The $5 million half-brother to champion racehorse Black Caviar is fighting for his life after being bitten by a white tail spider. The horse, known as Jimmy, is being treated at the Werribee Veterinary Clinic outside Melbourne. He was bitten about a fortnight ago but he suffered a reaction to the antibiotic administered after the bite. This caused Jimmy to suffer diarrhoea, which in turn has led to him developing laminitis, which is a disease that affects the hoofs and can prove fatal. Craig Cameron, chief executive of the horse's owners BC3 Thoroughbreds, says the next 48 hours will be critical. "It's awful. It's not just his racing potential, he's a horse that's got a great personality, he's well-loved by his owners and everyone at the stables," Cameron said."Any horse in the condition he's in is shocking to see."