Washington’s Toxic Plants Your Dog Should Avoid

Guest Post by Elena Edwards

UPDATED: 9/3/2020

Moo and I went on a camping trip with some friends in the Hood River area of Oregon over Memorial Day Weekend.

The area was super secluded, so I felt good about letting Moo off the leash to explore a little and have some fun herself (Moo’s not much of a wanderer, so she stays within sight).

Tansy Ragwort. Photo Credit: Kingcounty.gov

The hills were painted with bright yellow Tansy Ragwort, and by the end of the trip Moo was literally covered with the yellow petals from the tansy after roaming through the brush. No harm done, right? Just good ol’ outdoor exploration.

You can imagine my shock when I was relaying this story to a friend a few days later, and they told me they thought Tansy was poisonous to dogs.

Luckily, Moo is totally fine. She’s not one to taste-test many of her findings in the outdoors, so she must not have ingested anything. Still, it was an eye opener that I really don’t know anything about harmful plants in the Pacific Northwest.

Thus, I decided to compile a list of 14 plants you might find on the trails this summer in Washington that are poisonous for dogs.

Toxic Urban Plants

English Holly

Photo Credit: KingCounty.gov

English Holly is a tree or shrub that is primarily utilized within the Pacific Northwest as a decorative landscape plant.

However, English Holly is now considered a “weed of concern” in King County due to its encroachment into native forests.

It is considered mildly to moderately toxic to cats and dogs, so while you pup will most likely be good and sick if enough berries or leaves are ingested, life-threatening intoxication from this plant is very rare.

English Holly begins to bloom in the springtime, and will produce fruits in the fall (the leaves and berries are the poisonous parts of this tree if ingested).

Poison Effects:

Nausea, vomiting, drooling, diarrhea, drowsiness.

English Ivy

Photo Credit: Pixabay-Rkit

You’ve likely seen English Ivy growing within a garden, along a house, winding up a tree trunk, or spread throughout native habitats across the Pacific Northwest.

While it may be beautiful, it is considered a noxious weed in both Washington and Oregon, and its sale and cultivation is now banned due to its tendency to outgrow and choke out others plants.

Seriously, this stuff is all over the place. So much so that forests that are being invaded are now called “Ivy Forests”, which means you should keep your eyes peeled (and your dog on a leash) when hitting the trails.

All parts of English Ivy is poisonous to dogs if ingested (primarily the leaves though), and physical contact with the sap can create a rash on your pup.

Whether ingested or touched, your dog is likely to make a full recovery so long as your veterinarian is contacted as soon as symptoms begin to show.

Poison Effects:

Vomiting, diarrhea, spasms, staggering and paralysis

Horse Chestnut

Photo Credit: Pixabay-Utroja0

The Horse Chestnut is native to the mountainous-slopes of the eastern Balkan forests but has been introduced to North America.

Horse Chestnuts are pretty common in urban areas, so if you prefer taking your dog on hikes throughout town or in the city, it would be helpful to be able to differentiate this nut from the American Chestnut.

While ingesting of large amounts of the plant CAN result in death, the Horse Chestnut is infamous for it’s foul flavor, so it’s not super likely that any of our dogs would chow down enough material to really put their lives on the line.

More likely, a dog will show gastrointestinal symptoms anytime within 16 hours after eating any part of the plant.

Horse Chestnut trees are one of the first trees to leaf out as temperatures begin to warm, which was right around mid-May for Washingtonians this year.

Poison Effects:

Inflammation of mucous membranes, vomiting, thirst, weakness, muscular twitching, dilated pupils, stupor, stupor, paralysis, coma and death.

English Laurel

Photo Credit: Pixabay-Hans

English Laurel, also called the Cherry Laurel, can be found in urban and rural areas throughout Washington, and is currently considered a noxious weed in the state.

While this plant is most commonly found in urban forests (it’s well established within Seattle), it has since spread and naturalized in more remote areas, so keep an eye out on the trails (primarily west of the Cascades, and within the Puget Sound area).

English laurel is considered highly toxic, and if your pup (or you) consumed any part of the leaves, fruits or seeds of this plant, it should be treated as an emergency.

Wilted, fallen leaves contain the largest amounts of the toxic compound but laurel berries can also be very toxic to dogs if swallowed in large quantities (especially if they are chewed).

These guys are around all year, so they’re a good plant to be able to identify if you’re a year-round adventurer.

Poison Effects:

Abdominal pain, abnormal heart rate, diarrhea, muscle weakness, drooling, temporary blindness, tremors, seizures, coma.


Photo Credit: Pixabay- pixel2013

Ah alas, Washington’s beloved and beautiful state flower.

While I do love admiring these large, richly colorful flowers, they are unfortunately toxic, and much more so for dogs than humans.

Blooming in the spring, these beautiful, purple plants can be mildly to severely poisonous for dogs, depending on the amount ingested, as well as the hybrid of the plant (which comes in various colors).

It doesn’t take much to get a dog sick; in fact, if an animal ingests as little as 0.2% of their body weight in any part of the plant, they can be poisoned.

Rhododendrons can be found in the wild as well as within urban sprawl, so make sure to keep an eye out when walking past with you pup.

Poison Effects:

Burning of lips and mouth, salivation, nausea, severe vomiting, coma and death.

Toxic Rural Plants and Plants Found in the Forest

Wildflowers and forest plants in the Northwest are beautiful, often exhibiting bright colors.

While they might look harmless, you may be surprised to learn that several are highly toxic to dogs (and people).

Then there are some plants, like the salal bush and berries, that people think look toxic, or heard a rumor that they are, but actually aren’t (salal berries are not poisonous to dogs – in fact they are edible and quite tasty to some dogs and humans – and the leaves can be dried and used as medicinal tea).

To clear up some of the confusion, the most commonly encountered toxic plants found in the woods are listed below.

Common Tansy

Photo Credit: Pixabay-JacekAbramowicz

If you’ve lived or visited Washington in the summer, you’ve likely seen tansy ragwort (first picture in this article) and the common tansy. They grow about three feet tall and have golden, button-like clusters or flowers, and are actually quite pretty.

This weed is considered an invasive species to Washington State.

Originally used as an insect repellent (the fragrance of the weed helps repel ants and flies), Tansy has since naturalized throughout the United States, and can now be found along roadsides, streambanks, within pastures and in some forest areas.

All parts of the Tansy weed are considered highly toxic to dogs,
with the highest amount of alkaloids in flowers, then leaves, roots and stems. It even remains toxic when dry.

If consumed, call your vet immediately.

Poison Effects:

Rapid Pulse, dermatitis, head pressing, disorientation, stomach inflammation, convulsions, abortion, liver damage, kidney damage.

Death Camas

Photo Credit: http://thepoisondiaries.tumblr.com/post/24129059691/death-camas

I’ll start by saying that the name “Death Camas” speaks for itself.

Death Camas are cream colored flowering plants that are native to the western United States.

The flowers of the plant grow in clusters that somewhat resemble onion bulbs. The big difference, of course, is that onions are edible and Death Camas can kill you and/or your dog, which is why it’s so important to be familiar with how poisonous plants in your area look.

Death Camas flower between April and July, and generally grow in dry meadows and hillsides, as well as montane forests and sagebrush slopes, so it’s not unlikely that they could be in the same neck of the woods that you may be hiking.

The entire plant—bulbs, leaves, flowers and pollen—can be poisonous to both humans and dogs if consumed.

Poison Effects:

Salivation, weakness, respiratory difficulty, paralysis, urination/defecation, nausea, convulsions, coma, and (if not treated) death.

Death Cap Mushroom

Photo Credit: Pixabay-Skeeze

Of all the mushrooms that grow in the Pacific Northwest, the Death Cap Mushroom is a great one to be educated on for the sake of avoidance, for both you and your dog.

Similar in appearance to other edible mushrooms (Mother Nature has a sick sense of humor sometimes, doesn’t she?), the Death Cap Mushroom is one of the most poisonous mushrooms in the northern hemisphere.

They generally appear in summer and autumn months, and can be found in areas with oak, chestnut, and spruce trees, to name a few.

Poison Effects:

Severe abdominal pain, vomiting, diarrhea, gastrointestinal bleeding, coma, kidney failure, death.


Photo Credit: Pixabay-Shaymen99

Foxglove is a beautiful plant, with stacked bell-shaped lavender (they can also be white or yellow) flowers that grow tall and beautiful.

That being said, this plant contains a toxin found within its leaves, flowers and seeds that can be fatal to both humans and dogs if ingested (even the water that’s held within the vase part of the flower has been reported to cause toxicosis).

Foxglove blooms in early summer, and while they may be beautiful to look at on a sunny summer hike, I would recommend steering clear if you run into some.

There is no antidote for Foxglove poisoning, so for your pups sake, I wouldn’t risk it.

Poison Effects:

Contracted pupils, vomiting, diarrhea, cramps, severe headache, irregular heartbeat, labored breathing, convulsions, death.

Lily of the Valley

Photo Credit: Pixabay-IgorKon

Lily of the Valley is a highly poisonous woodland plant that is found in the Northern Hemisphere, and blooms in late spring.

Ingestion of Lily of the Valley will result in similar symptoms to that of Foxglove, and should be treated aggressively.

Similar to Foxglove, these dainty white teacup-like flowers grow in large colonies and are beautiful and easy to appreciate.

Sadly, all parts of the plant are highly toxic—stems, leaves, flowers and berries–and should be avoided if possible.

Poison Effects:

Burning pain in the mouth and throat, salivation, nausea, vomiting, abdominal pain, headache, dilated pupils, slow and irregular heartbeat, coma and death.

Poison Hemlock/Water Hemlock

Photo Credit: Paige Filler//https://www.flickr.com/photos/theequinest/2514584433

Poison Hemlock is a class B noxious weed within Washington, and can commonly be found along roadsides, in open fields, and basically in any natural, wild area. 

It’s considered severely toxic to both humans and dogs, and if ingested symptoms will start to show anywhere from 20 minutes to three hours later.

All parts of the plant are toxic, and even the dead canes remain toxic for up to three years (yikes)!

Poison Hemlock begins to grow in late spring, and has a history of being confused with wild carrots and other plants within the parsley family.

Similar in appearance to the Poison Hemlock is Water Hemlock, one of the most poisonous plants in Washington state.

Water hemlock is a wetland plant, and can commonly be found growing in pastures or along the edge of water and irrigation canals.

It’s wise to be able to differentiate these two highly toxic plants, however both are highly toxic and should be avoided to the best of your ability.

Poison Effects:

Teeth grinding, muscle spasms, delirium, respiratory failure, death

Bleeding Heart

Photo Credit: Pixabay- SusannP4

The Bleeding Heart plant is a beautiful pink, heart shaped (go figure) plant that commonly adorns gardens along the Pacific Coast of North America. A non-domesticated version also grows wild in the forest.

They’re beautiful additions to any garden and are sure to be show-stoppers, but these guys are moderately toxic to dogs. Luckily, they’re easy to recognize due to their distinctive shape.

These plants prefer moist climates, making the Pacific Northwest a perfect home. Within the wild, they can usually be found growing in lowland coniferous forests, specifically within thickets, stream banks and and ravines.

It’s the foliage and the roots of the Bleeding Hearts that are poisonous to pets if consumed.

Poison Effects:

Loss of coordination, tremors, drooling, difficulty breathing, seizures, possible death


Photo Credit: Pixabay-Rhiannon

Larkspur is an eye-catching blue, purple or white flowering plant found in Northern America that is toxic to humans, livestock, and pets if consumed.

This flowering plant likes moisture, and is usually found in meadows along mountainsides, where snowfall can be found late into spring and early summer.

While all parts of the Larkspur are considered toxic, it’s the new-growth and seeds that contain the highest concentration of toxins, meaning they’re more likely to be harmful when they first bloom (spring/early summer) and become gradually less-so in late summer.

Poison Effects:

Drooling, abnormal heart rhythms, constipation, abdominal pain, paralysis, tremors, seizures, heart and lung failure, death.

Bracken Fern

Photo Credit: Pixabay- KikiMiki

Bracken Fern is native to Washington, and is considered toxic primarily to cattle and humans.

That being said, if your dog is exposed to this plant on a regular basis (whether it be in your backyard, or along an urban or trail you walk regularly), it could pose a threat to your pup.

Apparently, a dog would have to ingest this fern somewhat regularly for a few months time before serious results would occur, and same goes for you. Nothing to lose sleep over, but something good to be aware of if your dog likes to munch on plants in the yard.

I included the bracken fern solely because, hey, this is Washington and our climate is home to ferns abundant.

By all means, please do not let this list of plants serve as a deterrent to getting outdoors with your dog. Rather, I hope this has served to better educate you on poisonous plants to be aware of when hitting the trails, and given you confidence in your ability to know a dangerous plant from a harmless one.

No adventure comes without it’s risks, but in my experience, it really is always worth it.

Make sure your dog avoids these plants on your next hike

About the Author

Hi, I’m Jessica. I’ve been studying the Dachshund breed since 2007, owned 3 of my own, and shared in the lives of thousands of others through their owner’s stories. When I’m not sharing what I know on this blog, you can find me hiking, camping, and traveling with my adventurous wiener dogs.


  1. I just lost my min pin of liver failure, she was only 5, any of the plants you mentioned are in my backyard, the Laurel, Rhododendrum, Fern, and you mentioned in the article onions for edible but they’re highly poisonous to dogs even onion powder so I would hope you would make a correction on that one because we didn’t know that and we would cook hamburger with gravy and onions for flavor and let the dogs eat the gravy on top of their food I unknowingly poison my own dog .

    I will be tearing out the plants in my yard this summer because losing a sweet dog that was only five years old was way too painful and it still is at times especially thinking it was my own fault .

    I’ve had dogs my whole life and never knew this, everyone said dogs can eat anything but that’s so untrue so if your dog has bad breath I mean like really bad breath that’s a sign somethings going on take her to the vet have a blood test done and only cost about 90 bucks, it’s better than $1600 for emergency veterinary care only to have your dog go into a coma and have convulsions and die in your arms two days later .

    Thank you for the article, I know the onion, was in regards to what humans eat but some people are just not capable of figuring that out so whatever people do don’t give your dog onions or anything with onions or onion powder in fact every time you feed your dog type the words into google “can I feed my dog (insert food item)”

    1. Hi Ernest. I’m sorry for your loss. There are many, many articles on the internet that discuss common household food toxins for dogs (both what is common in meals and what is commonly found in a backyard). Onions are on that list. However, I write about hiking with dogs, and I found the information about toxic plants found while hiking lacking, so I decided to write an article about potentially toxic plants found while out walking your dog. I’m sorry, but I don’t see where onion was mentioned in this article and specifically not where it was stated that onion was NOT toxic to dogs. If you can point out where you saw that, I can clarify.

      1. I think this is the comment that he was concerned with: “The big difference, of course, is that onions are edible and Death Camas can kill you and/or your dog”

        Thank you for writing this article! I have a new puppy that likes to taste EVERYTHING! Having info specific to PNW plants is so helpful. I’m going to bookmark this and review it often!

  2. If my dog eats bird poop and the bird has been gorging itself with English Laurel berries can he be poisoned?!

    1. Hi Connie. I’m not an expert on toxicity (not a vet). I just know the information I researched and compiled for this article. Logically though, my answer would be yes. Since the seeds can be toxic to dogs, and the seeds stay intact when eaten by birds, they likely still contain some level of toxicity when they are excreted. How much is what I don’t know. I would definitely talk to a veterinarian about that.

  3. Hi Jessica:

    We recently moved to the PACIFIC NW with a lab, Miley, from Colorado. There we had to worry about rattlesnakes. But since we moved here she’s been in the emergency room and almost died 5 times. 3 times from eating wasps (we think) and just yesterday from eating mushrooms (we think). We have always hiked with our dog daily and of course they love it especially off leash. Is there any articles about toxic mushrooms for dogs and also wasps? Thanking you in advance if you can help us.

    1. Hi Forest. That sucks that your dog got so sick here. It’s true that we don’t have a lot of obvious risks here but there are some – most specifically the ones you mention – that can be “sneaky” because you don’t think about them and they are hard to see. As far as the mushrooms go, I don’t know a lot about them and just assume ALL of them are toxic to dogs. We didn’t have any mushrooms in our yard until just this year (and we’ve lived here 10 years) so we go out every day or so and inspect the yard to remove any we see. We also watch our dogs to see if they are eating anything and go intervene. Unfortunately, with some mushrooms, just licking them can make a dog sick. Here is a really basic list of what is poisonous here: https://mushroomobserver.org/species_list/show_species_list/221. Keep in mind that this list is for humans and there may be a few others listed that effect dogs. In regard to the wasps and bees, I assume all are toxic because of the venom they release when they sting. The best “defense” there is to eliminate any nests in your yard. Here is a little more info on bees and wasps around the Northwest: https://www.doh.wa.gov/CommunityandEnvironment/Pests/BeesandWasps. Good luck to you guys!

    2. keep your dog on a leash. Better than death. Also they dont hike any further on a leash than off of it. Its your job to keep them safe. Off leash is not.

  4. The photo you used for English Holly is not of holly, it is of Tall oregon-grape, or mahonia aquifolium.

  5. Some people may think their dogs won’t like this fox-tail barrier, but they get used to it really quickly and it prevents them from eating weeds & more on hikes. My boston terrier likes to sneak-eat weeds, bird poop and the hawk’s left-over gopher bits which is all disgusting, and obviously can make a dog sick in many ways. So, in addition to blocking the foxtails, this helps a lot on hikes! Since a dog can gnaw through it if left UNATTENDED for too long, don’t expect it to be fail-proof, but if your dog is with you on a hike, they won’t be able to snack on anything accidentally! I love this thing; https://outfoxfordogs.com/

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