Police say a severely mutilated dog was discovered inside a kindergarten at Doncaster, in Melbourne's eastern suburbs.

The animal was dead when it was found by a worker at the Studley Street kindergarten at 7:30am (AEDT).

No children saw the dead animal.

Due to the dog's injuries, it was difficult to identify the breed, but it may be a kelpie cross between four and 10 years of age, that was mainly black with a white stomach and legs.

Police are trying to find the owner.

Detective Leading Senior Constable Mark Rogers says the attack is disgusting.

"It's a terrible thing for someone to grossly mutilate an animal in this way," he said.

Police want to hear from anyone who may have seen any suspicious activity in the area.