Sparrow had yellow marks all over his back and the acid appeared to get inside his mouth and into his organs, Valentina said.
She posted about the incident online and it was shared to a Facebook group where other members told her their cats had also been attacked.
She said it was heartbreaking that people could do this type of thing and the incident had been reported to police who told the Herald they were making enquiries.
Valentina said she wished people could live together in peace but said there are some people out there who did "horrific" things.
"He was in so much pain, the cry he was making was really haunting, it was just horrible," she said.
"He kept the family together … he was just the old boy and he was just a normal, loving, home-bodied little guy ."
Police asked anyone with information about the incident to contact North Shore Police on 09 477 5000.
Meanwhile, four puppies were dropped off in a black, plastic barrel in a park picnic area in Auckland today.
SPCA Auckland posted about the puppies, saying it was "remarkable" they survived after being exposed to the elements.
"They had no water, no shade, and no way for them to escape. We have no idea who did this to them. All we know is it's remarkable they survived.