Bryce has autism, is vision- impaired and has severe developmental issues.

Caleb, a 15-month-old labrador, was trained as a guide dog in Victoria but failed to pass the tests.

He will now be a protective ally for Bryce.

Caleb came into Bryce's life after the City of Devonport Lions Club heard about his situation and raised more than $1000 to buy the dog and bring him to Tasmania.

Bryce's parents John and Louise Gibson had decided to buy a specially trained companion dog to protect their first-born child's safety.

"Bryce is very adventurous and he tries to get out of the house," Mrs Gibson said.

"We don't want to be that family that you see headlining the news where an autistic child has walked out on to the middle of the road and is found dead.

"Every time we heard a story like that it was like a knife to the heart."

Mrs Gibson said the family researched companion dogs and discovered that they would cost more than $40,000.

She said they discovered a cheaper alternative in Guide Dogs Australia.

City of Devonport Lions Club president James McLagan said the organisation decided to step in and help.

"If it hadn't have been for the Lions club, we wouldn't have got this dog for some time. We are forever in debt to them," Mrs Gibson said.

"Caleb brings us so much joy every day and we have seen a significant change in Bryce already."

Mrs Gibson said Caleb could open and close doors and pick up dropped or other needed items.

She said if Bryce had a seizure, became lost or was in any danger, Caleb would use his "emergency bark".