Common Pet Poisons (A–Z)
Detailed reference pages for 50 common household and garden hazards affecting dogs and cats. Each entry includes toxic thresholds from veterinary toxicology literature, onset timelines, and immediate first-aid protocols.
Acetaminophen (paracetamol)
Why even part of a paracetamol tablet is dangerous for cats: Merck's 10 and 40–50 mg/kg figures, the signs that appear within hours, and what to do now.
Alcohol (ethanol and ethyl alcohol)
Ethanol from drinks, hand sanitiser or vanilla extract causes rapid poisoning in dogs and cats. Learn toxic doses, signs of hypothermia, and emergency care.
Aloe vera
Aloe vera latex acts as a strong laxative in pets, while the clear gel is milder. Learn the difference, the signs to expect and when to call your vet.
Amphetamine ADHD medications (Adderall, Vyvanse, and Ritalin)
ADHD stimulants like Adderall and Ritalin cause extreme agitation, dangerous heart rates and fever in pets. Learn toxic thresholds and emergency protocols.
Anticoagulant rat and mouse poisons
Rat bait anticoagulants cause bleeding 3–7 days after eating. Convert grams of 0.005% bait to milligrams of active ingredient and learn why the quiet first days are the time to act.
Asparagus fern
Asparagus fern berries and fronds irritate a pet's stomach and skin. Learn what to expect, simple first aid, and when a call to your vet is worthwhile.
Aspirin (acetylsalicylic acid)
Aspirin causes severe stomach ulcers and kidney injury in dogs, and is exceptionally toxic to cats. Learn feline sensitivities, toxic doses, and warning signs.
Autumn crocus (Colchicum autumnale)
Autumn crocus contains colchicine and can cause multi-organ failure; spring crocus usually does not. Learn how to tell them apart, the delayed signs and what to do now.
Bee and wasp stings
Most bee and wasp stings cause brief swelling, but allergic reactions and multiple stings are emergencies. Learn safe stinger removal, the warning signs and when to see a vet.
Black widow spider bites
Black widow venom causes severe muscle pain and cramps, and cats are especially at risk. Learn how to recognise the spider and the signs, and why to go to a vet straight away.
Blue-green algae (cyanobacteria) blooms
Toxic blue-green algae can kill a dog within hours of swimming. Learn how blooms look, the liver and nerve signs to watch for, and why rinsing and fast vet care matter.
Bromethalin (a brain-swelling rodenticide)
Bromethalin rat bait causes brain swelling, and cats are especially sensitive. Compare mg/kg with Merck's LD50 (0.4–0.71 mg/kg cats, 2.38–5.6 mg/kg dogs) and learn the two patterns of signs.
Brown recluse spider bites
Brown recluse bites can cause slow-healing skin wounds and, rarely, blood and organ problems. Learn how the lesion develops over days, simple wound care and when to see a vet.
Button batteries and alkaline batteries
Swallowed button batteries can lodge in the oesophagus and burn through it. Why you should not make your pet vomit, and what the vet will do.
Caffeine (methylxanthines)
Caffeine from coffee beans, energy drinks or alertness pills can trigger severe heart arrhythmias and seizures in pets. Review toxic thresholds and care.
Caladium and elephant ear plants
Caladium and elephant ear leaves and tubers contain oxalate crystals that make a pet's mouth sore. Learn which parts are worst, how to soothe the mouth and when to call a vet.
Cannabis (THC)
Dogs are very sensitive to THC: Merck reports signs from 0.3–0.5 mg/kg. Convert edible gummies to mg/kg, check for chocolate or xylitol, and see what to expect over 24 hours.
Castor bean (Ricinus communis)
Chewed castor beans release ricin, and one or two seeds can be fatal to a dog. Learn why signs are delayed, why castor meal fertiliser matters and what to do now.
Chocolate (theobromine and caffeine)
How much chocolate is dangerous for a dog? Convert the bar to milligrams of theobromine, compare it with Merck's 20, 40 and 60 mg/kg thresholds, and see when signs usually start.
Cholecalciferol (vitamin D3) rodenticide and supplements
Vitamin D3 rat bait and supplements can damage a pet's kidneys from as little as 0.1 mg/kg. Convert grams of bait or IU to mg/kg and compare it with the 0.1 mg/kg at which signs can begin.
Copper (coins, supplements and pipes)
Copper causes liver disease in some dog breeds and acute illness from supplements, while copper coins mainly pose blockage risks. Learn the difference and what to tell your vet.
Coral snake bites
Coral snake venom causes delayed paralysis with little swelling. Learn the nerve signs Merck describes, why monitoring lasts 48 hours, and why a normal-looking dog still needs a vet.
Dieffenbachia (dumb cane)
Dumb cane sap fires needle-like oxalate crystals into the mouth. Learn why pain is immediate, why there is no mg/kg dose, and the rare breathing warning sign to watch for.
English ivy (Hedera helix)
English ivy saponins can cause drooling, vomiting and diarrhoea in pets. See why berries may matter more than leaves, what to expect and when to call your vet.
Ethylene glycol (antifreeze)
A teaspoon of antifreeze can kill a cat. Convert millilitres to mg/kg, compare with Merck's lethal doses (1.4 mL/kg cats, 4.4–6.6 mL/kg dogs) and see why the first hours matter.
Foxglove (Digitalis purpurea)
Foxglove contains digitalis-type heart glycosides in every part. See which signs suggest heart involvement, why vase water counts, and what to tell your vet.
Golden pothos (Epipremnum aureum)
Golden pothos (devil's ivy) contains oxalate crystals that sting a pet's mouth. Learn what is normal after a chew, how to soothe the mouth and simple ways to prevent repeats.
Grapes, raisins, sultanas and currants
Grapes and raisins can cause kidney failure in dogs. Use Merck's one-grape-per-4.5-kg rule, the tartaric acid theory and the 24–72 hour timeline to decide how urgently to call.
Holly (Ilex species)
Holly berries and spiny leaves can upset a pet's stomach and scratch the mouth. Learn what to expect after a few berries and when to call your vet over the holidays.
Hops (Humulus lupulus)
Hops and spent brewing mash trigger fatal malignant hyperthermia and extreme fevers in dogs. Review signs, breed risks, and urgent cooling care.
Ibuprofen and other human anti-inflammatories (NSAIDs)
How many ibuprofen tablets are dangerous for a dog? Convert tablets to mg/kg and compare with Merck's stomach (100–125 mg/kg), kidney (175–300 mg/kg) and seizure (400 mg/kg) ranges.
Iron supplements and hand warmers
Iron tablets and prenatal vitamins can cause vomiting, bloody diarrhoea and liver damage in pets. How to work out the elemental iron dose and when to call.
Jade plant (Crassula ovata)
Jade plant (money tree) usually causes only mild vomiting in pets. Learn what signs to expect, home monitoring and when persistent signs need a vet.
Kalanchoe
Kalanchoe contains heart glycosides. Most pets only vomit, but large amounts can affect heart rhythm. See what to watch for and what to tell your vet.
Lead (sinkers, shot, old paint)
A swallowed fishing sinker can poison a dog slowly. Compare mg/kg with Merck's acute (191–1,000 mg/kg) and chronic (1.8–2.6 mg/kg/day) lead doses and learn the signs.
Macadamia nuts
Macadamia nuts can cause hind-leg weakness, tremors and fever in dogs. Compare grams eaten per kg with the 2.4 g/kg dose reported by Merck and see the usual 12–48 hour course.
Metaldehyde (slug and snail bait)
Slug pellets containing metaldehyde cause tremors, seizures and overheating in dogs. Convert grams of 2–4% bait to mg/kg and compare with Merck's LD50 of 210–600 mg/kg.
Mistletoe (Viscum and Phoradendron)
Mistletoe can cause vomiting and, in larger amounts, a slow heart in pets. Learn the difference between European and American mistletoe and what to tell your vet.
Nicotine (cigarettes, vapes, pouches and gum)
Vape pods, pouches and nicotine gum can poison a dog within minutes. Convert mg/mL and pieces into mg/kg and compare with the 1 mg/kg and 9–12 mg/kg figures in veterinary texts.
Oleander (Nerium oleander)
Every part of an oleander contains heart glycosides. Learn why no safe amount is published, which signs show heart involvement and why burning oleander clippings is also dangerous.
Onions, garlic, leeks and chives (Allium)
Onion and garlic can cause anaemia in dogs and cats days after eating. Compare grams eaten per kg with Merck's 15–30 g/kg (dogs) and 5 g/kg (cats) figures.
Organophosphate insecticides
Organophosphate and carbamate insecticides vary a hundredfold in toxicity. Learn how to turn a label percentage into mg/kg, which signs appear first and what to do right now.
Peace lily (Spathiphyllum)
Peace lilies cause mouth irritation in pets but not the kidney failure of true lilies. Learn how to tell them apart, what signs are normal and when to call a vet.
Permethrin (in dog flea treatments)
Dog flea spot-ons containing permethrin can cause tremors and seizures in cats. Convert a pipette to mg/kg, learn the signs and the 72-hour window, and what to do now.
Philodendron
Philodendron leaves contain oxalate crystals that sting a pet's mouth. Learn what is normal after a bite, simple ways to soothe the mouth and when to call a vet urgently.
Pit viper bites (rattlesnakes, copperheads, cottonmouths)
A rattlesnake or copperhead bite is an emergency. Learn the signs that follow, why tourniquets and cutting are harmful, and why the first 6 hours matter for antivenom.
Poinsettia (Euphorbia pulcherrima)
Poinsettias are only mildly toxic to cats and dogs. See what signs to expect, simple first aid for sap on skin or in the mouth, and when a vet visit is actually needed.
Pseudoephedrine and phenylephrine decongestants
Pseudoephedrine in cold tablets causes severe heart stimulation, extreme high blood pressure and seizures in pets. Review toxic doses and emergency actions.
Quaternary ammonium disinfectants (quats)
Quat disinfectants and floor cleaners can burn a cat's tongue and paws. Learn why concentration matters more than dose, how to rinse safely and why vomiting must not be induced.
Raw bread dough (yeast fermentation)
Raw yeast bread dough expands in a pet's stomach, causing dangerous bloat and alcohol poisoning. Understand the dual danger and why home emesis is unsafe.
Rhododendrons and azaleas (grayanotoxins)
Rhododendron and azalea grayanotoxins can slow a pet's heart after only a few leaves. Learn why there is no published dose, the signs to watch and why 'mad honey' is also toxic.
Sago palm (Cycas and other cycads)
Sago palm seeds can cause liver failure in dogs. Learn why no safe dose exists, how quickly signs appear, and what to tell your vet if a seed or leaf was chewed.
Salt and homemade playdough (hypernatraemia)
Excessive salt from homemade playdough, ornaments or seawater causes dangerous brain dehydration in pets. Check toxic doses and treatment protocols.
Snake plant (Sansevieria, now Dracaena trifasciata)
Snake plant (mother-in-law's tongue) contains saponins that can upset a pet's stomach. Learn what signs to expect, home care and when to call your vet.
SSRI and SNRI antidepressants
SSRI and SNRI antidepressants can cause fatal serotonin syndrome, tremors and fever in pets. Check toxic doses, feline risks, and urgent care protocols.
Tea tree oil and essential oils
Tea tree oil and essential oils cause severe stumbling, tremors and hypothermia in pets, especially cats. Learn safe decontamination and toxic risks.
Toads (especially the cane toad)
Toad venom contains heart toxins, and cane toads can kill dogs. Learn the first-aid mouth rinse recommended by Merck, the signs to watch for and when to go straight to a vet.
True lilies and daylilies
Any part of a true lily or daylily, even pollen or vase water, can cause kidney failure in cats. See which lilies are dangerous, the 24–72 hour timeline and why early vet care matters.
Tulip and daffodil (narcissus) bulbs
Tulip and daffodil bulbs hold far more toxin than leaves or flowers. Learn the difference between tulipalins and narcissus alkaloids, the signs to watch and what to tell your vet.
Xylitol (birch sugar)
Estimate a dog's xylitol dose from sugar-free gum or peanut butter and compare it with the 100 mg/kg low-blood-sugar and 500 mg/kg liver thresholds in the Merck Veterinary Manual.
Yew (Taxus species)
Yew needles and seeds contain taxine alkaloids that can stop the heart suddenly. Learn which parts are toxic, why clippings are dangerous to horses, and what to do now.
Zinc (pennies, nuts, bolts and zinc oxide cream)
One modern US penny holds about 2,440 mg of zinc and can destroy a small dog's red blood cells. Learn which coins and creams matter, the two phases of signs and what to do now.