A toddler was attacked by a dog between the Four Square supermarket and the bridge on Atawhai Cres.

Authorities are searching for a dog who attacked a Nelson toddler, leaving the boy with two puncture wounds to his face.

The 20-month-old was in a pram on Atawhai Crescent, Nelson, waiting to be put in the car when the attack happened about 5.30pm on Thursday.

Nelson City Council dog control manager Brent Edwards said the mother had been walking with her son and her dog, who was attached to the pram with a lead, when another dog came out of the bushes.

GOOGLE MAPS A toddler was attacked by a dog on Atawhai Cres.

The two animals started fighting, with the pram being pulled around in the process.

Edwards said the other dog jumped into the pram and put his mouth over the child's face. The boy suffered two puncture wounds; one on the eyelid and the other on the side of his head.

"On one hand the child was very lucky, certainly the injuries could have been a whole lot worse," Edwards said.

The dog has not been found.

The attack happened between the Four Square Supermarket and the bridge on Atawhai Cres.

St John paramedics attended and the boy and his mother were taken to Nelson Hospital.

Edwards said the mother was very distraught after the attack but the child was now back at home and "in good spirits".

He said the dog, which was described as being a medium-sized mixed breed with a tan-coloured body and a white face, ran off towards the bridge.

Edwards said the mother did not see an owner with the dog and believed it was a stray.

He said Nelson police and dog control searched the area but were unable to find it. They resumed their search again on Friday morning.

There was a report of someone exercising two dogs off leads in nearby Corder Park at the time. Edwards said they did not know if the dogs were related to the incident but they were keen to talk to the dogs' owner.

He said the dog might be dangerous and was keen to receive information that would help locate it. Anyone who can help is asked to contact Nelson City Council Dog Control on 03 546 0381.