Plants that are toxic to pets

Lilies, lily of the valley, oleander, rhododendron, dieffenbachia… More than 700 plants identified by the ASPCA Animal Poison Control are toxic to dogs or cats. And plant poisonings account for 10 to 15% of calls to French veterinary poison centres, according to the CNITV in Lyon. This guide reviews the most dangerous plants found in our homes and gardens, the symptoms by toxic family, and emergency first aid.

Why cats are most at risk

Cats are more vulnerable to toxic plants than dogs for two reasons:

• Oral curiosity: they instinctively chew green leaves (for fibre, or to make themselves sick).
• Unusual liver metabolism: cats lack glucuronidation enzymes, which slows the elimination of many plant substances (alkaloids, glycosides).

Dogs, which spend more time outdoors (garden, walks), are exposed to garden plants (oleander, yew, rhododendron, wisteria), spring bulbs and rotting leaves in compost.

The most dangerous: top 10 life-threatening emergencies

1. Lilies (Lilium spp.) — Extremely toxic to cats. Pollen, vase water, a petal, a leaf: acute kidney failure within 24-72h, with a death rate > 50% without immediate hospitalisation. Includes water lilies, oriental lilies, tiger lilies and daylilies. In dogs, moderate gastrointestinal toxicity.

2. Lily of the valley (Convallaria majalis) — Cardiotoxic glycosides (convallatoxin). Arrhythmia, slow heart rate, low blood pressure, possible seizures. The whole plant is toxic, including the vase water.

3. Oleander (Nerium oleander) — One of the most toxic ornamental plants. Glycosides similar to digitalis. A few leaves can kill a large dog. Symptoms: vomiting, arrhythmia, heart block, seizures, death within 24h.

4. Yew (Taxus baccata) — Contains taxine, a cardiotoxin. Death can occur within hours from ventricular fibrillation. Especially dangerous because it is often planted as a hedge.

5. Rhododendron / Azalea — Grayanotoxins. Vomiting, drooling, slow heart rate, respiratory depression. A few leaves are enough to poison a small dog.

6. Dieffenbachia / Philodendron / Pothos / Monstera — Aroids containing calcium oxalate crystals. Immediate burning of the mouth, swelling of the tongue and larynx, risk of airway obstruction.

7. Tulips, hyacinths, daffodils, amaryllis — Toxicity is concentrated in the bulbs. Vomiting, diarrhoea, depression, seizures. Especially dangerous for dogs that dig in the spring garden.

8. Weeping fig (Ficus benjamina), rubber plant (Ficus elastica) — Irritant latex, digestive ulcers, drooling.

9. Sago palm (Cycas revoluta) — Cycasin, a severe liver toxin. Death rate of 50-75% in dogs despite treatment.

10. Horse chestnut (Aesculus hippocastanum) — Aesculin and saponins. Vomiting, diarrhoea, neurological problems. Very common in urban parks, and dangerous in autumn when the conkers fall.

Other common plants to watch out for

Houseplants: aloe, asparagus fern, azalea, cyclamen, croton, ficus, hydrangea, morning glory, jasmine, kalanchoe, ivy, poinsettia, snake plant (sansevieria), schefflera, peace lily (spathiphyllum), yucca.

Garden plants: arum, deadly nightshade, box, honeysuckle, chrysanthemum, autumn crocus, datura, foxglove, bracken, wisteria, mistletoe, holly, iris, jonquil, lupin, peony, castor oil plant (extremely toxic), Christmas rose, elder, thuja, privet.

Food plants: tomato stems, leaves and green fruit; potato leaves; rhubarb (leaves); onion, garlic, shallot; grapes (toxic to dogs: acute kidney failure).

Full detailed list: ASPCA Toxic and Non-Toxic Plants Database (can be filtered by species).

Recognising symptoms by toxic family

Cardiotoxins (foxglove, lily of the valley, oleander, yew): slow or fast heart rate, arrhythmia, weakness, collapse.

Neurotoxins (datura, horse chestnut, castor oil plant): tremors, seizures, loss of coordination, coma.

Liver toxins (sago palm, amanita mushrooms): jaundice, repeated vomiting, loss of appetite, liver damage within 24-72h.

Kidney toxins (lilies in cats, grapes in dogs): acute kidney failure, no urine output, uraemia.

Mechanical irritants (oxalates: dieffenbachia, philodendron): immediate mouth pain, drooling, swelling.

Digestive toxins (most plants): vomiting, sometimes bloody diarrhoea, abdominal pain.

What to do if your pet eats a plant

Step 1 — Identify:

• Photograph the plant (leaves, flowers, fruit, stem).
• Keep a sample (leaf, berry).
• Note the approximate time it was eaten and the estimated amount.

Step 2 — Call for help immediately:

• Your usual vet or an emergency vet service.
• In France, a 24/7 veterinary poison centre: CNITV Lyon (04 78 87 10 40) or CAPAE-Ouest Nantes (02 40 68 77 40).

Step 3 — DO NOT:

• Do not make your pet vomit without veterinary advice (some corrosive plants cause more damage on the way back up).
• Do not give milk, oil or salt water.
• Do not give "home-made" charcoal.

Step 4 — Transport: keep your pet covered and bring the photo and the plant sample.

Prevention: create a pet-safe environment

• Audit your home: list all your houseplants and check each one against the ASPCA database. Replace toxic ones with safe alternatives.
• Safe alternative plants: pilea (Chinese money plant), calathea, chlorophytum (spider plant), maranta, peperomia, plectranthus, lucky bamboo (Dracaena sanderiana), Boston fern, areca palm, kentia palm.
• Bouquets you receive: remove lilies, lily of the valley, gypsophila and eucalyptus immediately, before putting the flowers in water.
• Garden: fence off areas with oleander, yew or rhododendron. Always pick up fallen conkers and acorns. Keep an eye on spring bulbs.
• Compost: keep it out of dogs' reach (mould toxins).
• Cat grass (Cyperus zumula, wheatgrass): offer some to your cat to channel their urge to chew greenery towards a safe plant.

Conclusion

More than 700 plants can poison a dog or a cat. Prevention starts with an audit of your home and garden, checking each plant against the ASPCA database. If you suspect your pet has eaten something, do not waste time: photograph the plant, call a vet or a poison centre, and do not improvise any "home remedy". For cats, the rule is simple: never have lilies in the house, ever.