"This cat clearly suffered a horrific fate, and would have felt a great deal of fear and pain in this violent act," Ms Burgess said.
"Unfortunately, it is not uncommon that animals are victims of violence, with companion animals such as in this case being at the mercy of humans within the home. If they are mistreated, they are often unable to protect themselves.
"Sadly, animals are often considered as 'things' by those responsible for their care and treated as such, and not as the sentient beings they are who warrant protection from neglect, violence and suffering."
Police arrested the woman and took her to Northern Beaches Hospital for assessment. She was later released into police custody and taken to Manly Police Station.
The woman was charged with torture, beating and causing the death of an animal, and committing an act of aggravated cruelty on an animal, and bail was refused.
She is due to appeal in Many Local Court today.
The second cat is now in the care of RSPCA NSW. A spokesman for the organisation said the animal is under veterinary assessment and "appears to be doing well".