A 77-year-old man has been fined $3,000 after drowning a neighbour's cat in his wheelie bin at Brighton on Brisbane's northside.

Donald Carrington this morning pleaded guilty in the Sandgate Magistrates Court to one count of inhumane killing of an animal.

Magistrate Orazio Rinaudo labelled Carrington's actions "completely reprehensible".

No conviction was recorded.

The court heard Carrington had been suffering anxiety because of a serious illness and feral cats had been keeping him awake at night.

He was also ordered to pay nearly $2,000 in costs.

The cat's owner, Usha Goode, says the animal had been kept under control.

"It's been a really, really horrible experience," she said.

"I had registered him with the council, I had desexed him, and he had my home phone number and my mobile phone number on him and he was always inside at night-times."