A 37-year-old man who allegedly fatally stabbed a pet dog at a park in Perth's north has been charged with animal cruelty.

The four-year-old Labrador's owner, a 22-year-old woman identified only as Bridgette, said she took two dogs to Apple Blossom Polyantha Reserve in Mirrabooka on Wednesday evening and let them run around off their leads.

Bridgette said she saw the dog, named Luna, approach a man who also had a dog, but did not hear any barking or yelping as the man bent down.

She tried to speak to him but he walked away and jumped over a fence, which she thought was odd.

Bridgette put her other dog in her car and went looking for Luna, expecting to find her sniffing around a tree.

"I get closer and I realise she's on the floor, blood all over her and I just drop and start screaming and screaming," she told reporters on Thursday.

Bridgette took the dog to a veterinary hospital but the dog could not be saved.

The man has been bailed to appear in the Perth Magistrates Court on June 15.

AAP

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