Vets at the animal charity examined Jack and realised a rare condition had left him completely blind in his left eye and with only 20 per cent vision in his right.
They diagnosed him with Chorioretinitis, a swelling and irritation of the middle layer of the eye, which is irreparable.
Kate Brewster, 27, of the Dogs' Trust, said Jack would have been 'terrified' racing with no vision in his left eye - used by dogs to follow the rabbit.
She said: 'We don't think Jack's racing owner realised the severity of his blindness and it would have been terrifying for him to race because of the noise.
'He must have followed the other dogs or maybe used his sense of smell to get around the track. He clearly had no way of seeing the rabbit.'
Jack stills runs very fast at the shelter, where he knows exactly where the fences are. The animal charity says Jack will make a great pet, and hopes to find him a home with no small children or other pets. Link -via Arbroath
(Image credit: SWNS)