Toxic to dogs · Plants

Are Rhododendrons toxic to dogs?

Extreme severity No safe amount — No amount is considered safe.

Yes, Rhododendrons are extremely toxic to dogs. Even a small amount can be life-threatening, so treat any exposure as an emergency and contact a vet immediately. No amount is considered safe.

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Are rhododendrons toxic to dogs and cats?

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What to do right now

  1. Call your vet or an animal poison line now, even if your dog seems fine. In the US: Pet Poison Helpline (855) 764-7661 or ASPCA Animal Poison Control (888) 426-4435.
  2. Don't make your dog vomit at home unless a vet tells you to. Whether it is safe depends on your dog's condition, so the vet decides.
  3. Call even if it happened a few hours ago. Plant material often stays in the stomach for many hours, so the vet may still be able to remove it.
  4. Note which plant it was, roughly how much your dog ate and when. Larger amounts cause more severe poisoning.
  5. Keep your dog away from the plant so it can't eat more.

Go to an emergency vet if

  • Your dog is weak, collapses, has trouble breathing, or has a very slow or irregular heartbeat.
  • Your dog trembles, has a seizure, seems blind, or is very dull or hard to wake.
  • Your dog keeps vomiting, drools heavily or has diarrhea.
  • Your dog ate more than a leaf or two, or you don't know how much. The ASPCA says a few leaves can cause serious problems.

Symptoms to watch for

  • drooling
  • vomiting
  • diarrhea
  • abdominal pain
  • inappetance
  • abnormal heart rate
  • heart arrhythmias
  • weakness
  • hypotension
  • depression
  • tremors
  • transient blindness
  • seizures
  • coma

How much is dangerous

No source gives a measured toxic dose for dogs. Pet Poison Helpline says severe signs may occur in dogs that eat only a few leaves or flowers, and a Vet Times article says one or two leaves, stems or flowers, including the nectar, can be fatal to a small dog. The Merck Veterinary Manual's table of toxic ornamental plants gives a toxic dose of 1 g of plant per kg of body weight, without saying which animal it applies to. The figure of 0.2% of body weight sometimes quoted comes from cattle. Don't use these figures to judge your dog's risk. Treat any chewing as urgent.

When signs appear

Signs usually start within 1 to 4 hours of eating the plant, and occasionally as late as 12 hours, according to the Merck Veterinary Manual. A Vet Times article says they can begin within minutes. Signs may last several days. Even when a pet has only stomach upset, Merck says vets typically monitor it through the day for heart problems.

Why it's dangerous

Grayanotoxins disrupt sodium channels, which negatively affects the function of skeletal and cardiac muscles.

Toxic compound: grayanotoxin

How vets treat it

There is no specific antidote, so treatment is supportive. If your dog has no signs yet, the Merck Veterinary Manual recommends making it vomit, then giving anti-nausea medicine and one dose of activated charcoal. Once signs have started, this is done only if the dog is neurologically stable, and a Vet Times article advises against inducing vomiting at all, so your vet weighs the risks. IV fluids support blood pressure, and the heart rate and blood pressure are monitored until your dog goes home. Vets may give atropine for a slow heart rate, medicines for abnormal rhythms, methocarbamol for tremors, anti-seizure medicines, oxygen for breathing problems, and treatment for vomiting and diarrhea.

Outlook

Small ingestions that cause only stomach signs have an excellent outlook, according to the Merck Veterinary Manual. Larger ingestions that cause heart or nervous-system signs have a guarded to good outlook with aggressive care. A Vet Times article says the toxins are cleared quickly and patients can go home within two days of admission. Pet Poison Helpline warns that without prompt veterinary care, large ingestions can be fatal.

Where pets are exposed

  • Rhododendrons and azaleas, which both belong to the Rhododendron genus and are also called rosebay. They grow indoors and outdoors as ornamental plants, shrubs and small trees.
  • Every part of the plant, including the pollen and nectar. The nectar, flowers, leaves and stems are of greatest concern, and flowering plants attract pets.
  • Honey made from rhododendron nectar, known as mad honey. It contains the same toxins, and most poisonings in people come from it.
  • Related plants with the same toxins: mountain laurel (Kalmia), Japanese pieris, and fetterbush or staggerbush (Lyonia).

Prevention

  • Don't grow rhododendrons or azaleas where your pet can reach them, and keep potted azaleas out of your home if your pet chews plants. Flowering plants attract pets.
  • Every part of the plant is toxic, including the flowers, leaves, nectar and pollen, so fallen flowers and leaves are a risk too.
  • Don't leave pruned branches or clippings where pets can reach them. Animals have been poisoned after eating cut branches and pruning waste from these plants.
  • Watch for related plants with the same toxins, such as mountain laurel and Japanese pieris.
  • Keep a close eye on dogs and cats while you work on rhododendrons and azaleas.

Good to know

All parts of the plant are poisonous; ingestion of as little as 0.2% of an animal's body weight can cause poisoning.

Common questions

Are rhododendrons and azaleas toxic to dogs?

Yes. Every part of the plant contains grayanotoxins, which bind to sodium channels in nerve and muscle cells, including the heart. Even a few leaves can cause vomiting, diarrhea and drooling, and larger amounts can cause heart rate and rhythm problems, low blood pressure and seizures, and can be fatal. Call your vet or a pet poison line right away if your dog chews one.

Are azaleas poisonous to cats?

Yes. The ASPCA lists azaleas as toxic to cats, and Pet Poison Helpline says severe signs may occur in cats that eat only a few leaves or flowers. The ASPCA Animal Poison Control Center received 188 reports of dogs and cats eating azaleas between 2001 and 2003, with vomiting, depression, diarrhea and loss of appetite. No toxic dose for cats has been published, so treat any chewing as urgent and call your vet.

How much azalea is toxic to a dog?

No source gives a measured toxic dose for dogs. Pet Poison Helpline says a few leaves or flowers can cause severe signs, and a Vet Times article says one or two leaves, stems or flowers can be fatal to a small dog. Figures given as a share of body weight, such as 0.2% in cattle, come from livestock and don't tell you your dog's risk. Treat any amount as an emergency and call your vet.

How long after eating an azalea will my dog get sick?

Signs usually start within 1 to 4 hours, and occasionally as late as 12 hours, according to the Merck Veterinary Manual, and they may last several days. Call your vet as soon as you know your dog ate some, without waiting for signs. Plant material often stays in the stomach for hours, so the vet may still be able to remove it.

Which part of a rhododendron or azalea is poisonous?

All of it, including the pollen and nectar. The Merck Veterinary Manual says the nectar, flowers, leaves and stems are of greatest concern. Honey made from rhododendron nectar, called mad honey, also contains the toxins. Call your vet or a pet poison line if your pet eats any part of the plant.

Sources

This page is informational and is not veterinary advice. If your pet has been exposed to something risky, contact your vet or an animal poison control line right away.

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