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Is Tansy Toxic to Dogs? Signs and What to Do

PawAI Lab
7 min read

Learn whether tansy poses a toxicity risk to dogs, which parts are most hazardous, and the steps a veterinarian may recommend after exposure.

Quick Answer

Yes, tansy (Tanacetum vulgare) is toxic to dogs. The plant contains thujone and other essential oils that can affect the nervous system and the liver. All parts of the plant may pose a risk, with the flowers and leaves typically containing the highest concentrations of these compounds. If your dog chewed or swallowed tansy, contact a veterinarian or an animal poison-control service right away, even if your dog appears well at this time.

Before using any tool, contact a veterinary professional if your dog may have eaten tansy.

  • US: ASPCA Animal Poison Control (888-426-4435) or Pet Poison Helpline (855-764-7661)
  • UK: Animal PoisonLine (01202 509000) or your nearest veterinary emergency clinic
  • Canada: ASPCA Animal Poison Control (888-426-4435) or Pet Poison Helpline (855-764-7661)
  • AU: Animal Emergency Centre or your regular vet
  • EU: Contact your nearest veterinary emergency service

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Safety Verdict

Toxic. Tansy (Tanacetum vulgare) contains thujone, a monoterpene ketone, along with other essential oils. Thujone can affect the central nervous system and, in sufficient amounts, may also damage the liver. All parts of the plant may contain these compounds, with the flowers and leaves typically carrying the highest concentrations. The plant is sometimes used in gardens or grows wild in meadows and along roadsides.

Because thujone can affect the nervous system and liver, no part of the tansy plant should be considered safe for a dog to chew or swallow. The risk applies to fresh plants, dried material, and any products made from tansy.

What Should the Owner Do Now?

  1. Contact a veterinarian or animal poison-control service immediately. Early assessment can help reduce the risk of nervous system or liver complications.
  2. Do not induce vomiting unless a veterinarian or poison-control professional directly instructs you to do so.
  3. Collect relevant information (see the section below) so the veterinary team can assess the situation accurately.
  4. Do not give food, milk, salt, charcoal, or any home remedy. These are not proven treatments and may worsen the situation.
  5. Follow the veterinarian's instructions regarding whether to bring your dog in for examination, monitoring, or supportive care.

Even if your dog chewed only a small amount and seems fine, professional consultation is still warranted because signs may not appear for several hours.

What Signs May Occur?

Signs of tansy toxicity in dogs may develop within a few hours of ingestion, though the timeline can vary. Not all signs will appear in every dog.

Early signs may include:

  • Vomiting
  • Diarrhea
  • Drooling or excessive salivation
  • Reduced appetite
  • Lethargy or depression

Because thujone affects the central nervous system, additional signs may appear as toxicity progresses:

  • Ataxia (unsteady walking or loss of coordination)
  • Tremors or muscle twitching
  • Seizures in severe cases

Liver effects may develop over a longer timeframe and can include:

  • Yellowing of the gums, skin, or whites of the eyes (jaundice)
  • Increased thirst or changes in urination
  • Continued lethargy or weakness

Because tansy can affect both the nervous system and the liver, veterinary monitoring may be recommended even when a dog initially appears stable.

What Information Should Be Ready?

When you contact a veterinarian or poison-control service, having the following details available can help them assess the situation more efficiently:

  • Dog's details: species, breed, approximate age, and body weight
  • Plant involved: tansy (Tanacetum vulgare), and whether the dog chewed leaves, stems, or flowers
  • Estimated amount: best guess of how much plant material was swallowed
  • Time of ingestion: when the exposure occurred, or the window of time during which it may have happened
  • Current symptoms: any vomiting, diarrhea, drooling, lethargy, ataxia, or tremors
  • Plant sample: if available, a photo or a piece of the plant to confirm identification
  • Medical history: any pre-existing liver disease, neurological conditions, or current medications

Provide honest estimates rather than precise measurements. The veterinary team can work with approximate information to determine the best course of action.

Differences That May Affect Risk

Several factors can influence how tansy affects an individual dog:

  • Part of the plant: The flowers and leaves typically contain the highest concentrations of thujone and essential oils. Stems may contain lower amounts but are still unsafe.
  • Body size: Smaller dogs may be at greater risk from a given amount of plant material, though toxicity is possible in dogs of any size.
  • Existing liver conditions: Dogs with pre-existing liver disease may be more vulnerable to additional liver effects from thujone.
  • Individual variation: Reactions can differ between dogs, and the amount ingested is not always easy to determine.

Because of these uncertainties, any known or suspected ingestion should be treated as potentially serious.

When to Contact a Veterinarian

Contact a veterinarian or animal poison-control service immediately if your dog has chewed or swallowed any part of a tansy plant. Do not wait for symptoms to appear.

Emergency signs that require urgent veterinary attention include:

  • Persistent vomiting or diarrhea
  • Unsteady walking or loss of coordination
  • Tremors or seizures
  • Weakness or collapse
  • Any change in your dog's responsiveness

Non-urgent follow-up: If the ingestion occurred hours or days ago and your dog appears normal, a veterinary examination is still recommended to check for delayed nervous system or liver effects.

FAQ

Is tansy toxic to dogs if they only chew the leaves?

Yes. The leaves of tansy contain thujone and other essential oils that can affect a dog's nervous system and liver. While the flowers may carry higher concentrations, the leaves are not considered safe. Any ingestion should be discussed with a veterinarian.

Can tansy cause seizures in dogs?

Tansy contains thujone, which can affect the central nervous system. In sufficient amounts, it may be associated with tremors or seizures in dogs. Not every dog that eats tansy will develop these signs, but any ingestion should be treated as potentially serious and discussed with a veterinarian.

How is tansy poisoning in dogs treated?

Treatment may include decontamination under veterinary direction, intravenous fluids, and supportive monitoring of the nervous system and liver. If seizures occur, a veterinarian may manage them with appropriate medication. A veterinarian determines the appropriate approach based on the individual case.

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Disclaimer

This article and the PawAI Toxicity Checker provide general safety information and cannot determine an individual pet's toxicity risk or replace a veterinarian or animal poison-control service. If exposure may have occurred, contact an appropriate professional promptly, even if your pet appears well.

Written by PawAI Lab