It is estimated that more than 72,000 children aged between three and 10 have autism in the UK.
By Denise Glass
BBC Scotland news website, Tayside reporter
Now a campaign has been launched to raise £1m to provide specially trained dogs to help youngsters with the condition.
Lacey stops Joe from running away in the street
It is understood that the first child in mainland UK to receive one of the dogs was Joe from Dundee.
He was diagnosed with autism when he was two.
His mother, Paula Craik, said it was hard to cope.
She explained: "Joe was frustrated being in shops, noisy crowds, bright colours.
"He would get distressed and he would lash out."
"If you tried to hold his hand and walk down the street he refused, he didn't like the touch of your hand.
"He wanted to go another way and would bolt and you would have to run after him."
Ms Craik then heard about an organisation in Canada that had been successfully training dogs for youngsters with autism and was determined to find one for Joe.
She got in touch with the charity Support Dogs who agreed to help.
However, Joe had to get used to being around dogs first, so once a week he went with his mother to Forfar Guide Dogs.
Then after many months of searching, Joe was introduced to Lacey and after almost a year of training the Labrador moved in with the family.
Joe, who is now five, is attached to Lacey's harness and the dog is trained to make sure he cannot run into dangerous situations.
The family is also now able to go to the shops and to doctors', dentist and hospital appointments without Joe having an episode.
Joe's vocabulary has also improved - before he would only say and understand about 10 words, now he is learning Spanish.
Ms Craik also believes people are more willing to talk to Joe now he has Lacey.
She said: "Before people wouldn't approach us, because I assume they thought he was a badly behaved child.
"Now people will come up and look at Joe and he'll look at them in the face.
"They'll ask him questions like 'What's your dog's name?' and say 'What a special dog you have' and he responds.
"It may be in gibberish and they can't understand what he's saying, but the fact that he's responding, that's all that matters."
Three-year-old Lacey is about to embark on further training which will see her learn extra safety skills.
She will learn how to stand in front of him and push him back if she detects that he is in danger.
Ms Craik has said that having Lacey around has allowed them to have a life, whereas before they did not.
She added: "I want to thank Support Dogs for giving us hope for Joe's future.
"Before it was very uncertain what kind of future he might have, whereas now we have hopes that he could lead a fairly normal life.
"Lacey is Joe's best friend."