FrançaisMy dog ate weed: what should I do?
Call your vet or a pet poison line now, even if your dog seems fine. Cannabis can make dogs wobbly, drowsy and leak urine, and signs usually start within 1 to 2 hours of eating it [1]. Most dogs recover, but strong products and edibles carry more risk [1, 2]. Tell the vet what your dog ate, how much and when: these facts guide the care [11].
Cannabis poisoning in dogs is becoming more common. In Colorado, cases seen at two hospitals rose 4-fold from 2005 to 2010, while medical marijuana registrations rose 146-fold [2]. Calls to the ASPCA Animal Poison Control Center about dogs and cannabis went from 179 in 2009 to 362 in 2014 [10]. In a 2021 survey, veterinarians in Canada and the US reported more cases after October 2018 [5].
Edibles, joints, dried plant and concentrates
THC (delta-9-tetrahydrocannabinol) is the part of cannabis that makes people high [1]. How much a product holds varies a lot [1]:
- Dried plant, joints and leftover butts: usually 4 to 20% THC [1].
- Hash and hash oil: 20 to 50% THC [1].
- Concentrates (dabs, wax, shatter, oils): up to 80 to 90% THC [1].
- Edibles (brownies, cookies, gummies, candy), tinctures, capsules and vape liquids: very variable [1]. Edibles were the products vets suspected most often in a North American survey [5].
- Human feces in public places: in Melbourne, 15 dogs were poisoned after eating human feces that likely contained THC, mostly in local parks [7]. In a US study, 28% of dogs showed sudden nervous-system signs after going outside or to a public place [6].
Edibles bring extra risks. Brownies and other baked goods made with cannabis butter caused the two dog deaths reported in Colorado [2]. Edibles can also contain chocolate or xylitol, which are toxic on their own [5, 10]. Keep the wrapper or recipe for the vet.
CBD products are made to contain little THC, but poorly made ones can have wrong labels and contain THC or other cannabinoids, which may explain wobbly or drowsy dogs after CBD [16].
Why THC affects dogs so much
THC acts on CB1 receptors in the brain and nerves. Dogs have more of these receptors in the cerebellum, which controls balance, and in the brainstem, which controls heart rate and breathing. This likely explains why dogs wobble so much and why their heart rate can change [1].
THC dissolves in fat and is stored in body tissues, then slowly released. Its effective half-life is about 30 hours. Dogs pass about 85% of it in their feces and 15% in their urine, and clear 80% within 5 days [1].
Signs, timing and how long it lasts
After eating cannabis, signs usually start within 1 to 2 hours, up to 4 hours in a dog with an empty stomach [1]. Smoke acts within minutes [1]. In 213 dogs, signs started between 5 minutes and 96 hours, most often 1 to 3 hours after eating, and lasted from 30 minutes to 96 hours [3]. In severe cases, signs can persist for 1 to 3 days [1].
- Wobbliness and drowsiness: the most common signs. In 223 dogs, 88% were unsteady and 63% lethargic [6].
- Dribbling urine: urine leaking without the dog noticing, seen in 46% of these dogs [6].
- Startling at touch or sound: 75% of dogs were over-sensitive (hyperesthesia) [6]; dogs can flinch at movement and noise [1].
- Heart and temperature: a slow heart rate [1, 4], or a fast one in 37% of dogs [6]. Body temperature can drop or rise [1].
- Other signs: vomiting, drooling, dilated pupils, trembling, head bobbing, agitation [1, 4]. Seizures are rare [1].
Most dogs do well. All 223 dogs in the US study survived [6], and all followed dogs recovered in the 213-dog series [3]. Deaths are very rare and have followed edibles made with concentrated cannabis butter [1, 2].
Why being honest with the vet matters
Vets know this situation well. Because some of these drugs are illegal, some owners give incomplete or misleading histories [11], and in one study 68% of owners denied that their dog could have been exposed [6].
The signs of cannabis look like other poisonings: human medicines that stimulate or sedate, some antiparasitic drugs, xylitol and hallucinogenic mushrooms [4]. Without the true story, the vet may need more tests to rule these out. Timing also matters: making a dog vomit is only considered within about an hour of eating, in a dog with no signs yet [1]. Telling the vet what, how much and when helps your dog get the right care faster [11].
What the vet checks, and why
There is no reliable quick test for THC in dogs [1]. Human urine drug tests, sold in pharmacies, often give false negatives in dogs because dogs break THC down into products these tests do not detect [1, 4]:
- Abbreviation K or potassium, in the electrolyte block with sodium (Na) and chloride (Cl).
- Result 5.6 mmol/L in this illustrative line: a little above the interval. Mildly high potassium was found in 39 of 76 tested dogs with cannabis poisoning [6].
- Unit mmol/L or mEq/L: for potassium the two numbers are the same.
- Laboratory interval The example uses the dog interval of the Merck Veterinary Manual [14]; each laboratory sets its own.
- Flag H: above the interval. In this study, blood work was otherwise mostly normal and all dogs survived [6]. The vet reads the value with the heart rate and the other results.
| Check | What can be found | Why it matters |
|---|---|---|
| Neurologic exam | Wobbliness, startling, urine leaking | The usual basis of the diagnosis, with the history [5, 6] |
| Heart rate, blood pressure, temperature | Slow or fast heart rate, high blood pressure, low or high temperature | Followed every 1 to 4 hours in dogs with signs [1, 6] |
| Glucose | Low if the edible held xylitol | Xylitol causes low blood sugar, which also makes dogs wobbly and lethargic [12] |
| Potassium and calcium | Mildly high | Found in about half of tested dogs (potassium) and most (ionized calcium) [6] |
| Blood count, liver and kidney values, urinalysis | Usually normal | Used to rule out other causes; no difference from healthy dogs in a small study [6, 13] |
| Laboratory THC test (blood or urine) | THC and its breakdown products | Accurate but slow, so rarely used to decide care [1, 9] |
- In a 2009 study, a human urine test detected several drugs in dogs, but not marijuana [8].
- In Colorado, 6 dogs known to have eaten marijuana tested negative [2].
- In a 2021 study, 20 of 21 urine samples from affected dogs tested negative, although THC was found in the blood of all 19 dogs by a laboratory method [9].
Care and outlook
Care is supportive: there is no antidote [4]. Depending on the dog, the vet may make it vomit if it ate the cannabis very recently and has no signs, give fluids and anti-nausea medicine, control its temperature and keep it in a quiet, calm place [1]. Mildly affected dogs may be watched at home if the vet agrees [1]; in the survey, outpatient monitoring was the most common care [5].
The outlook is good: signs usually fade within 1 to 3 days [1], and most pets recover completely [5].
Related articles
All foods and substances toxic to pets: toxic foods for dogs and cats.
En français : cannabis et chien.
Questions to ask your veterinarian
- Could the edible also contain chocolate or xylitol, and should glucose be checked?
- Are my dog’s heart rate, blood pressure and temperature normal?
- Do we need tests to rule out other poisons or diseases?
- Can my dog be watched at home, or does it need to stay?
- What signs mean I should bring my dog back?
Get your dog’s emergency blood results explained.
AI DiagAnimals reads glucose, potassium, calcium and the full blood work together with your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
I think my dog is high. What should I do at home?
Call your vet or a pet poison line now. There is no safe way to sober a dog up at home: do not make it vomit or give it anything unless the vet tells you to. Vomiting is only considered by the vet, within about an hour of eating, in a dog with no signs [1], and hydrogen peroxide given at home damaged the stomach lining of all healthy dogs tested [15].
Will my dog be OK if he ate weed?
Most dogs recover completely [3, 5], and deaths are very rare [1]. In a study of 223 dogs, all survived [6]. Strong edibles made with cannabis butter carry more risk [2], so call your vet.
How long does a high last in a dog?
Signs usually start 1 to 2 hours after eating [1] and usually fade within 1 to 3 days [1]. In 213 dogs, they lasted from 30 minutes to 96 hours [3].
My dog ate an edible gummy. What should I do?
Call your vet or a pet poison line now, with the package if you have it. Gummies and other edibles can hold a lot of THC [1] and may also contain xylitol or chocolate, which are toxic too [5]. Xylitol can cause low blood sugar, so the vet may check glucose [12].
How much weed can harm a dog?
Signs have been reported from about 0.3 to 0.5 mg of THC per kg of body weight, with moderate signs above 2 to 3 mg/kg [1]. In one series, the lowest amount of plant that caused signs was 84.7 mg/kg [3]. Products vary widely in strength [1]. Call your vet or a pet poison line whatever the amount.
Sources
- Hommerding H. Toxicosis in Dogs and Cats From Tetrahydrocannabinol (THC). Merck Veterinary Manual, full review February 2026. merckvetmanual.com/toxicology/toxicoses-from-human-recreational-drugs/toxicosis-in-dogs-and-cats-from-tetrahydrocannabinol-thc
- Meola SD et al. Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005-2010). J Vet Emerg Crit Care. 2012;22(6):690-696. doi.org/10.1111/j.1476-4431.2012.00818.x
- Janczyk P, Donaldson CW, Gwaltney S. Two hundred and thirteen cases of marijuana toxicoses in dogs. Vet Hum Toxicol. 2004;46(1):19-21. pubmed.ncbi.nlm.nih.gov/14748410
- Fitzgerald KT, Bronstein AC, Newquist KL. Marijuana poisoning. Top Companion Anim Med. 2013;28(1):8-12. doi.org/10.1053/j.tcam.2013.03.004
- Amissah RQ et al. Prevalence and characteristics of cannabis-induced toxicoses in pets: results from a survey of veterinarians in North America. PLoS One. 2022;17(4):e0261909. doi.org/10.1371/journal.pone.0261909
- Binagia EM, Gregory EA, Yankin I. Clinical examination findings and electrolyte abnormalities of dogs with marijuana/tetrahydrocannabinol toxicity: 223 cases (January 2017-July 2021). J Am Vet Med Assoc. 2024;262(8):1047-1054. doi.org/10.2460/javma.24.02.0092
- Lauinger CA, Peacock R. Marijuana toxicosis in dogs in Melbourne, Australia, following suspected ingestion of human faeces: 15 cases (2011-2020). Aust Vet J. 2022;100(3):90-97. doi.org/10.1111/avj.13134
- Teitler JB. Evaluation of a human on-site urine multidrug test for emergency use with dogs. J Am Anim Hosp Assoc. 2009;45(2):59-66. doi.org/10.5326/0450059
- Fitzgerald AH et al. Detecting and quantifying marijuana metabolites in serum and urine of 19 dogs affected by marijuana toxicity. J Vet Diagn Invest. 2021;33(5):1002-1007. doi.org/10.1177/10406387211027227
- Howard-Azzeh M et al. The impact of state cannabis legislation, county-level socioeconomic and dog-level characteristics on reported cannabis poisonings of companion dogs in the USA (2009-2014). PLoS One. 2021;16(4):e0250323. doi.org/10.1371/journal.pone.0250323
- Hovda LR. Overview of Toxicoses in Animals From Human Recreational Drugs. Merck Veterinary Manual, full review February 2026. merckvetmanual.com/toxicology/toxicoses-from-human-recreational-drugs/overview-of-toxicoses-in-animals-from-human-recreational-drugs
- Hayes C. Xylitol Toxicosis in Dogs. Merck Veterinary Manual, updated 2025. merckvetmanual.com/toxicology/food-hazards/xylitol-toxicosis-in-dogs
- Pereira HCDS et al. Comparison of clinicopathologic findings and urine drug screen results in cannabis-positive and control dogs. Front Vet Sci. 2025;12:1679400. doi.org/10.3389/fvets.2025.1679400
- Merck Veterinary Manual. Serum biochemical analysis reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/serum-biochemical-analysis-reference-ranges
- Niedzwecki AH et al. Effects of oral 3% hydrogen peroxide used as an emetic on the gastroduodenal mucosa of healthy dogs. J Vet Emerg Crit Care. 2017;27(2):178-184. doi.org/10.1111/vec.12558
- Hommerding H. Toxicosis in Dogs and Cats From Cannabidiol (CBD). Merck Veterinary Manual, full review February 2026. merckvetmanual.com/toxicology/toxicoses-from-human-recreational-drugs/toxicosis-in-dogs-and-cats-from-cannabidiol-cbd
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.