Former jockey Mick Fitzgerald has said the photo of Gordon Elliott on social media has brought great sadness as he tried to stress that horses are cared for in racing.
The image, posted and widely shared on Twitter on Saturday, shows Elliott sitting on a dead horse on the gallops, with many considering it to be a photoshopped image.
Elliott confirmed the photo was genuine in a statement last night and offered an apology.
Betfair has discontinued its association with the trainer, while the Irish Horseracing Regulatory Board has launched a full investigation.
Speaking on Sky Sports Racing, an upset Fitzgerald said: "My initial reaction to it was: 'I hope it's a fake'. I thought it has to be a fake.
"We're not in control of all the facts but from what we can see, and when I read that statement [from Elliott], I can't help but feel anything else but feel so sad.
"The number one thing that we have to get out to everybody is how much we care about these horses. It's so important that anyone who has any interest at all in our sport that at the heart of this [the racing industry] are people who love these animals.
"It's making me quite emotional because these horses have given me a life that I'm privileged to have. It just makes me so sad.
"I've been in situations where horses I look after and ridden have unfortunately paid the ultimate sacrifice in our sport and the care and attention they get right until the very end is so important. It is so important people know we care for these horses.
"We want to celebrate them [the horses]. We want them to realise how much we care and how much they are loved by everyone in the sport. We have nothing but the interest of these animals at heart."