A woman is behind bars after she allegedly stabbed her cat to death before throwing it from the balcony of her second-floor unit on Sydney’s northern beaches.

Celina Shead, 19, is accused of stabbing the animal about 20 times before police found the body on the footpath outside a block of flats on Mooramba Road at Dee Why.

Officers spoke to a neighbour who called triple zero before taking the pet to a vet, who revealed it had been stabbed “multiple times”.

The pet was an 11-year-old male cat named Ginger.

A second cat was found uninjured and has been placed in the care of the RSPCA.

Ms Shead was handcuffed and taken to Northern Beaches Hospital, where she underwent a mental health assessment.

She was released into police custody and was taken to Manly Police Station, where she was charged with torture and causing the death of an animal, as well committing an act of aggravated cruelty upon an animal.

Ms Shead has been refused bail and is due to face Manly Local Court this morning.

It is believed the woman lived at the unit with her father and sisters, who were not at home at the time of the alleged attack.

-ABC