Rachel Plummer - the mother of the young boy - said they were walking by the Water of Leith in Colinton Dell at around 3.30pm on April 1 when the incident happened.
She said: “My son Robin is intellectually disabled, he was eating his leftover sandwiches from his school packed lunch when the dogs came over.
"There were seven or eight dogs, maybe more, off the lead and many without even a collar on.
"One of the dogs without a collar ran over to us and tried to snatch Robin's sandwich but Robin didn't let it go at first, he doesn't understand, and so the dog went for him, knocking him down and biting at his arm and shoulder.”
Robin was left “very distressed” but thankfully was not badly hurt in the attack as he was wearing several layers, although his legs were bruised and his back was scraped from being knocked over.
Ms Plummer continued: “I screamed at the top of my lungs when I saw it go for him. He's only a little boy, very small for his age and slow to respond due to his disabilities, and the dog was easily as big as him.”
After they got the dog off Robin, Ms Plummer, and a friend who had been walking with them, tried to explain what had just happened to the dog owners who had been too far away to witness the incident themselves.
She said they did not respond to the news that one of their animals had attacked a child and instead “ran off”, refusing to share their names.
Ms Plummer said that all they said before leaving the dell was “stop following me” and “you shouldn’t have been having a picnic in a dog walking area”.
After they returned home, Ms Plummer reported the incident to the police.
A police spokesperson said: “Around 4.15pm on Thursday, April 1, officers received a report of an incident involving a child and a dog in the Colinton Dell area of Edinburgh.
"Enquiries to establish the full circumstances are at an early stage.”