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The deadly ripple effect of rat poisons

Rat poisons can cause slow, painful deaths and harm far more than their intended targets. Lucy the possum’s story reveals the devastating ripple effect on native wildlife and the need for safer, more humane rodent control.

RSPCA Australia
Tuesday, 27 October 2026

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A wildlife rescuer was called to a neighbour’s house after an adult possum had fallen four metres onto concrete.

It was an extraordinary fall to survive. But when the rescuer arrived, the possum was wet and lethargic, with a tiny joey clinging to her.

The rescuer rushed both to nearest vet, but sadly, the mother possum did not survive. However, tests showed it was not the fall that caused her death; she fell because she was already dying due to ingesting rodenticide.

For her joey, who carers have now named Lucy, the following days were critical. Because some rodenticides can pass through a mother’s milk, Lucy was also at risk of secondary poisoning and needed immediate treatment. Dehydrated and around 60 grams underweight, she began daily vitamin K supplements to help her blood clot normally and reduce the risk of serious internal bleeding and organ failure.

Today, Lucy is progressing well, with no signs of internal damage so far. With dedicated care, her prognosis looks hopeful. But her story is not an unusual one; dozens of non-target species including native birds, mammals, and reptiles have shown evidence of second-generation anticoagulant rodenticide poisoning and carers say the numbers are increasing. Their suffering, and the suffering these poisons cause the animals they do target, is one of the serious welfare issues in managing rodent populations right now.

How do rodenticides work?

Rodenticides used in Australia fall into two main groups: anticoagulant and non-anticoagulant rodenticides. In March 2026, the Australian Pesticides and Veterinary Medicines Authority (APVMA) imposed a one-year suspension on products containing second-generation anticoagulant rodenticides (SGARs), after finding that their use posed unacceptable risks to non-target animals, including native wildlife. However, this is an interim restriction rather than a complete ban. SGARs can still be supplied and used under strict conditions, including by professional pest controllers, while their proposed classification as restricted chemical products is implemented. This means wildlife can still be accidentally poisoned by these products.

SGARs are particularly concerning because they are highly potent and can remain in an animal’s body even after death. The poison may therefore travel beyond the rat or mouse that consumes the bait, affecting owls, kookaburras, other native birds and mammals, and companion animals that encounter or eat the contaminated rodent.

Anticoagulant rodenticides kill by preventing the blood from clotting normally, causing internal bleeding and a slow, painful death that may take several days. First-generation products, including warfarin and coumatetralyl, generally need to be eaten more than once to be fatal. More potent SGARs, such as brodifacoum, bromadiolone and difenacoum, can kill after a single feed. Both raise serious animal welfare concerns.

Death can take days

One of the biggest animal welfare concerns with anticoagulant rodenticides is that they don’t cause a quick or humane death. A humane death is the result of immediate unconsciousness followed by a rapid death, without pain, suffering or distress.

By comparison, a rat or mouse poisoned with rodenticide can take up to seven days to die. During this time, bleeding can occur in their joints, muscles, body cavities, and organs. The animal may become weak, have difficulty moving or breathing, and experience significant pain and distress as their condition gets worse.

They can remain conscious the entire time while their body shuts down. It is a slow and painful death that no animal, labelled ‘pest’ or otherwise, deserves.

Animals affected by secondary poisoning can also endure the same effects. As internal bleeding develops, affected animals may become weak and disoriented, struggle to move or breathe, and suffer significant pain and distress before collapsing or dying. Because these signs do not appear immediately, affected wildlife can be difficult to find and treat in time. The impacts can extend far beyond the animal targeted by the bait, which underscores the far-reaching harm these poisons have the potential to cause.

Sentience and suffering should be the catalyst for better regulation

Rodents are sentient animals, capable of experiencing fear, pain and distress. Their capacity to suffer should be central to every decision regarding how they are managed. Where control is necessary, using the most humane method available should be paramount.

However, it’s currently not a mandatory requirement to use the most humane method available, and most individuals who purchase the available anticoagulant rodenticides are unlikely to be aware of the relative humaneness of different methods. There is an urgent need for scrutiny and stronger oversight of the animal welfare impacts of the use and availability of chemical toxins in population management, especially when there are already more humane methods available. The potential for secondary poisoning, and the impact on wildlife and companion animals in environments where these baits are used, must also be seriously considered.

Requiring every new and existing control method to be assessed for humaneness and potential environmental impact would help ensure animal welfare is properly considered, and that animals are not subjected to avoidable pain, suffering, or distress.

Prevention can help avoid the need for poison

The most humane way to manage rodents is to prevent them from entering homes and sheds in the first place. Properties near bushland, parkland or other open spaces can be more vulnerable to mice, while cracks, gaps and loose brickwork in older buildings can make it easier for rats and mice to get inside. A few simple, inexpensive precautions can reduce the likelihood of an infestation:

Store opened food and animal feed in metal, glass or heavy-duty plastic containers with tight-fitting lids, and discard uneaten pet food or store it securely if it is still fresh.
Clean up food scraps, animal litter and other rubbish inside and outside the home, and place waste in sturdy bins with secure lids.
Put rubbish out on the morning of collection rather than leaving bags or bins on the footpath overnight.
Remove weeds, debris, unused materials and other clutter that could provide shelter or nesting sites.
Keep windows fitted with intact screens and outside doors closed. Use metal trim where needed to prevent rodents gnawing beneath doors.
Check the home, shed, garage and basement for possible entry points, and seal cracks, holes and gaps.
Store firewood and garden supplies on raised platforms with clear space underneath so rodents have fewer places to hide.

By taking these few simple steps to limit access to food, water, and shelter, you can make your property less attractive to rodents and reduce the likelihood that lethal control will be needed. Prevention protects your home while helping to avoid pain and suffering for rodents, wildlife, and companion animals.

Sometimes rodents may still need to be managed. Animal welfare still matters.

There will be situations where rodent populations need to be controlled - but that doesn’t mean every method of control is appropriate. The first priority should be prevention and exclusion. If further control is needed, it is important to consider whether the method is effective, what suffering it may cause and what other animals could be affected. Where large-scale control of rodent infestations is needed, RSPCA urges government agencies, community landholder groups and pest control operators to use more humane alternatives, to carefully follow strict codes of practice (COPs) and standard operating procedures (SOPs), and to minimize the devastating impacts of chemical pest control on non-target native wildlife.

While the Australian Pesticides and Veterinary Medicines Authority’s review of anticoagulant rodenticides is currently underway, RSPCA Australia continues to call for animal welfare to be properly considered in the regulation of these products, for harmful anticoagulant rodenticides to be deregistered, and for more humane approaches to managing rodents to be developed and promoted.

Knowledgebase • Offsite

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