Wildlife carers are asking dog owners to tether their pets at night after a pregnant koala died following a vicious attack on North Stradbroke Island on January 2.
Two dogs attacked the koala, named Bulla, in the Terra Bulla Leumeah Conservation area, near Myora Springs.
Australia Zoo Wildlife Hospital said Bulla was euthanised a day after the attack, which left the koala in shock and with a fractured right arm, a dislocated left knee and about 20 bites.
Straddie vet Jade Patterson calmed the animal and anaesthetised her to conduct a thorough physical examination, bandage her arms and leg and administer antibiotics.
Bulla died at Australia Zoo, where she had been in intensive care. The tiny joey in her pouch also died.
Island koala expert Romane Cristescu said Bulla also had a juvenile koala on her back but the pair were separated during the attack.
Ms Cristescu said the injuries were so severe vets said her chances of survival had been slim and her recovery would have involved multiple surgeries and months of care.
Australia Zoo vets asked pet owners to confine cats and dogs at night.
"This attack has resulted in two, possibly three, koala deaths and could have been prevented if the dogs were tied up at night."
Ms Cristescu thanked the Straddie Flyer for taking Bulla to the mainland for free and Redland City Council for funds to buy the drugs and equipment.