At least 300 animals have been reported missing since Christchurch's big earthquake, an animal welfare organisation says.

SPCA spokeswoman Stef Saunders said most of those missing are cats, which had taken fright after the quake and hid.

Dogs had tended to be more "clingy" in the aftermath of the quake and remained near people.

The SPCA shelter was housing 65 animals, 34 of which had come in after the quake, but it was not "bursting at the seams" yet.

Animals had reacted to aftershocks in very different ways.