The RSPCA says it is horrified by the third shooting attack on an animal in less than two weeks.
A kangaroo has had to be put down after it was shot by an arrow in Toodyay.
In another incident, a dog in the East Kimberley was also shot with an arrow, while a horse in Anketell south of Perth was hit by a bullet from a shotgun.
The RSPCA's Tim Mayne says the organisation cannot account for the sudden spike in attacks.
"We don't really have any indication as to why this is happening other than there's a bunch of idiots running around with weapons that think it's OK to shoot defenceless animals," he said.
"I can assure these people that this is not a joke, that these crimes are punishable by quite hefty penalties."
Mr Mayne says punishments such as a $50,000 fine or five years in jail can be given to those convicted of animal cruelty.
"The message here is that if you inflict injuries or any form of cruelty on defenceless animals and we catch you, then we will enforce the full extent of the law and you will be punished," he said.
The RSPCA is calling for the public's help to catch those responsible for the attacks.