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Common Poisons Encountered in Pets

Common Poisons Encountered in Pets

The most common pet poisonings to be mindful of;

Pets can encounter lots of different toxins in their home environment which can cause illness and even death. It can pay to know which items in your household can be potential problems for your pets, and which poisons will act quickly and how they can affect your pets both short term and long term. Remember; poisons are designed to kill!

This list is not exhaustive by any means, and covers some of the more common toxicities we encounter in veterinary medicine. If you suspect your pet has eaten something that may be harmful, seek immediate veterinary advice to ensure the best outcome.


Snailbait is a commonly used poison in most backyards and especially after good rain. Snailbait comes in 3 main types: The blue pellets are usually a carbamate or organophosphate toxin, the green pellets are usually metaldehyde, and the red pellets (often marketed as being ‘pet friendly’) are an iron phosphate base. All come in a pelleted form that is often attractive to pets, and although some have bittering agents to deter consumption by pets this often doesn’t work well (cats being the exception as they really don’t do bitter taste).

The blue and green pellets work on the central nervous system and require a very small dose to be toxic. Signs include mild tremors and agitation, moving to uncontrollable tremors and seizures and death. Unfortunately this kind of snailbait is often used in malicious poisonings. Iron pellets can affect the liver and intestinal tract, and whilst a larger dose is often needed to produce toxicity, it is still toxic to pets. Clinical signs include vomiting and diarrhoea, sometimes with blood and liver insult.

If your pet ingests any kind of snailbait, prompt veterinary attention is required!!


Rodent poisons include anticoagulants (bleeding toxins) and Vitamin D analogues. Access to baits should be prevented by placing baits in inaccessible areas (though rodents can move baits), tamper-proof containers or using traps instead of poison. If poisons are used, dead rodents should be removed promptly to prevent secondary poisoning from pets consuming dead rodents.

Anticoagulants include warfarin and the newer generation compounds such as brodifacoum. Warfarin has a higher toxic dose and a shorter duration of action, whereas the newer rodenticides have smaller toxic doses and extended durations of action. These work by creating clotting problems and animals often present with signs of bleeding which may range from a nosebleed that won’t stop, to coughing of blood, to catastrophic chest or abdominal bleeds. Toxic doses take only days to drop clotting factors enough to cause bleeding.

Vitamin D rodenticides work by creating abnormally high levels of calcium within the body. Calcium is very finely regulated and is involved with processes such as nerve conduction, muscle movement as well as other functions. High levels of calcium can injure the kidneys and other organs and impair muscle contractility, including that of the heart.
Treatment for Vitamin D toxicity can be difficult and prolonged and can leave your pet with lifelong organ and tissue damage.

Pets seen to eat rodenticides should have immediate gastrointestinal clearance through vomiting or lavage, and if you suspect your pet has eaten rodenticides but a significant amount of time has passed we still need to address the prolonged actions of the poisons and the damage they can do.

Paracetamol and Aspirin:

Paracetamol and aspirin are commonly used in people for pain and fever and some curious pets find the blister packaging interesting and end up eating human doses of the medication.

Paracetamol can affect the blood cells and liver and can cause death within hours. Cats are more sensitive as they lack an enzyme to efficiently metabolise the compound. Signs can include swollen face, difficulty breathing, muddy gums and weakness. Prompt stomach decontamination and aggressive treatment are required. The prognosis is poorer in cats.

Aspirin is an anti inflammatory and can cause gastrointestinal bleeding when chronically used, and severe electrolyte and acid-base disturbances in acute overdoses, leading to neurological damage. Acute overdoses require immediate veterinary attention.

Ethylene Glycol (Antifreeze):

Antifreeze is sweet to taste and this can lead to animals consuming toxic quantities readily when access is available. Toxicity is more common in colder climes where antifreeze is in regular use.

Toxicity occurs within minutes, and immediate decontamination is imperative. Ethylene Glycol is metabolised into toxic compounds that affect the nervous system and kidneys through alcoholic compounds and crystal deposits in the kidney structure leading to acute kidney failure. Once clinical signs are advanced prognosis for recovery is poor. Even with prompt treatment a successful outcome is not guaranteed.

Psychotropic Medications (Antidepressants, Stimulants):

Accidental poisonings with human medications are becoming more common. ADHD medication as well as medications for anxiety and other mental health disorders can pose a serious overdose risk for pets even though some of these compounds are also used in pets. Human doses are often larger than those prescribed to pets, and accidental ingestion can be fatal.

Most antidepressants stimulate the central nervous system and too much stimulation can result in tremors and seizures and a syndrome known as Serotonin Syndrome. Serotonin Syndrome manifests as agitation +/- aggression, high blood pressure, and tremors which then progress to seizures. Toxicity can result in permanent brain damage and death.

Stimulants, such as those used for ADHD act similarly to cocaine in some ways, and stimulate other neurotransmitter pathways, resulting in overstimulation of the central nervous system with agitation, repetitive behaviours and eventually seizures.

Depressants such as valium and others depress the central nervous system and overdose can result in mental depression, loss of coordination, respiratory depression and death.

If your pet is showing signs of central stimulation or depression, and you are taking any medications for mental health be sure to let your veterinarian know it is a possibility.


Ivermectin belongs to the group of parasite control medications called Macrocylic Lactones. These compounds work by depressing the nerve activity in parasites as much less concentrations than would affect larger mammals. However, overdoses will produce nerve depression in mammals as well. The Collie breeds are often more susceptible as they can have mutant variation of a gene that allows the compound to enter the brain at lower concentrations compared to other breeds.

Common exposure occurs when pets are dosed with cattle-concentrated backlines, overdoses in over-the-counter flea products and on ‘baited’ carcasses.

Clinical signs can include mental depression, dilated pupils, stumbling or difficulty walking through to coma and death. Treatment is largely supportive and can take days.

Aflatoxin and Penitrem A (Fungal Toxins)

Mushrooms and other fungi can contain aflatoxins or Penitrem A which can impair liver or cause tremors and seizure-like activity. Mouldy compost eating is a common source of poisoning.

Aflatoxins produce vomiting and malaise, followed by liver damage that may be mild through to severe enough to cause jaundice, clotting problems and death. There is no antidote and supportive care is required, as well as serial monitoring of liver health and clotting ability.

Penitrem A produces tremors and nervous system stimulation through an unknown mechanism, but likely it interferes with the ability of nerves to ‘switch off’. Clinical signs can vary widely from malaise and agitation through to full blown seizure activity. Treatment is supportive and should be instigated as soon as possible.


Lilium species (true lilies) are a common household flower, especially in bouquets. All parts of the plant are extremely toxic to cats and ingestion of even a tiny part of the plant can lead to irreversible kidney damage.

Clinical signs often occur within hours, and include quietness, depression and vomiting. As kidney damage progresses excessive drinking and urination may occur, though death may occur before this.

Immediate decontamination and washing of the fur (if pollen is present) as well as aggressive fluid therapy and serial kidney monitoring is essential. Prognosis is guarded if prompt attention is received, and poor if clinical signs of kidney damage are already evident.

5-Fluorouacil (1080 bait, 5-FU Cream)

5-FU is used widely as a pest-control bait on larger properties and by government regulatory authorities. It is also available as a cream for humans for pre-cancerous skin treatment (common product is Effudex, Adrucil).

5-FU is extremely toxic and small doses can be fatal. It produces a neurological stimulation and interferes with cellular mechanism that produce cellular energy.

Ingestion results in most cases in rapid clinic signs, though they can be delayed by some hours. Clinical signs include tremors and agitation, gastrointestinal signs, vocalisation and mania, followed by seizures and respiratory distress and death. IMMEDIATE veterinary attention is required, DO NOT DELAY.

Treatment is difficult, with no specific antidote. Prognosis even with treatment is guarded to poor.


Cannabis is a widely used recreational drug and accidental exposure is not uncommon. Not to be confused with CBD oil which does not contain the psychoactive components of cannabis, nor hemp oil which is largely omega oils.

Clinical signs include wobbly gait, confusion, tremors, urinary incontinence and mental depression.

Treatment is supportive and prognosis is favourable.

There are many, many toxins in the world but luckily most pets don’t either encounter them, or eat the vehicles they present in. Lots of garden plants and ornamental shrubs contain toxins ranging from mild irritants to cardiac blockers. Herbivores are more likely to encounter plant toxins owing to their dietary preferences (and more likely in drought conditions when grass is less available) and yard clippings. A few that are particularly toxic include:

Yew: Yew plants (Taxus spp) contain cardiac glycosides which act quickly and have no antidote. Only a small amount of plant is required to produce death even in large livestock. Clinical signs include incoordination, tremors, trouble breathing and sudden death from heart block. Treatment is supportive and often unrewarding.

Rhododendron: Rhododendrons contain grayantoxins which affect nerve cell conduction. Affected animals often show a very painful abdomen, and vomiting of rumen contents followed by heart arrhythmias, weakness and death. Treatment is supportive.

Avocado: Avocado plants and fruit can be toxic, with leaves being the most toxic part. It causes death of the heart muscle and can cause mastitis in lactating animals.

Oleander: Oleander plants are extremely toxic to all mammals. Plants contain cardiac glycosides which, like Yew, produce early clinic signs associated with gastrointestinal irritation, followed by heart arrhythmias and death.

Many more poisonings in stock can occur through seasonal variations in pasture (rainfall, stress, stage of plant growth), and with supplementary feeding.

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