WA owner speaks after dogs euthanised

The owner of two dogs euthanised after mauling a nine-year-old boy south of Perth says she has never had any problems with the dogs before and she is in shock over the attack.

Ambulance crews were called to a Cooper Street home in Mandurah on Friday morning to treat the youngster for head and arm injuries.

He has been transported to Princess Margaret Hospital in Perth after initially being taken to the nearby Peel Health campus.

His mother and grandmother, aged 50 and 29, were also treated for lacerations.

The owner of the female mastiff cross and male American bulldog surrendered the pets to authorities and the animals were then euthanised, a spokeswoman for the City of Mandurah said.

The owner, who did not want to be named, said the three injured people were her relatives and were at the house minding her children while she was out.

"I'm in shock," she told the Mandurah Mail newspaper.

"There was blood everywhere."

The woman said she had owned the dogs since they were puppies and they had never been violent before.

"You can ask our other neighbours - we've never had any trouble with them," she said.