Cyclist Richard Twose, who hopes to compete at the Rio Games in 2016, was pushed and kicked near his home in Fareham, Hampshire.
The partially-blind 35-year-old and his dog Bates were both injured in the unprovoked attack.
Mr Twose told The News: "I decided to take (Bates) out for walk. That’s when I heard him yelp in pain. I turned around and a split second later I was pushed into the fence and kicked in the stomach.
"I was lying on the floor trying to protect myself.I could just make out feet kicking me. I couldn’t tell how many there were, but there was definitely more than one person."
Twose, who has won 13 medals in the World Transplant Games, suffered a bruised pancreas and has been told to stop training until the New Year. The injury also affects his work as a personal trainer.
His dog is spending the weekend with carers as he recovers from the incident.
Mr Twose added: "My back hurts, my stomach hurts and my hips hurt. I’m normally a confident person. This has knocked my confidence. I won’t go out again after dark.
"It’s knocked Bates too. He was needy yesterday. Me and Bates together are strong, but without each other, I don’t know.
"I just hope he is going to be okay."