An American Saddlebred show horse in critical condition after ingesting unknown quantities of oleander leaves is recovering and will be released from the hospital later this week, according to the veterinarian supervising its treatment.

"He's looking brighter and turning the corner," said Steven V. Colburn, DVM, of the Creekside Veterinary Service hospital where the horse is under treatment.

The horse is among 23 Saddlebreds–including two pregnant mares–sickened after someone placed a mixture of oleander leaves and carrot and apple bits in their stalls and in an outdoor corral at Rockridge Farm in Rancho Santa Fe, Calif., last Thursday.

Three of the horses were taken to the hospital after the incident. Two were released earlier this week. The remainder were treated at the farm, said Colburn