The half-brother to champion mare Black Caviar is on the improve but still not out of the woods, according to BC3 Thoroughbreds spokesman Simon Marshall.

The two-year-old colt developed the hoof disease laminitis after he was bitten by a spider.

His life hung in the balance while he fought the disease at the Werribee Veterinary Clinic but Marshall says he is looking a lot better.

BC3 Thoroughbreds paid an Australian record $5 million at the Easter yearling sale for the colt, affectionately known as Jimmy.

"He looks terrific - his coat is a lot better," said Marshall.

"He's a resilient colt and he's fighting the fight which is giving us hope.

"With laminitis it is a day-to-day thing."

Marshall said the horse was coping well after vets eased his medicine.

"But he's not out of the woods yet," said Marshall.

Although the chances of the colt being able to race are limited, if he can be saved he is a valuable stallion prospect.

He is by multiple Australian champion sire Redoute's Choice out of Helsinge who, in addition to the unbeaten Black Caviar, has also produced another multiple Group One winner, All Too Hard