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Cannabis and THC Exposure in Dogs and Cats: Signs, Doses and Honest Conversations

Updated October 21, 2026 · By the PureOrganism editors

A pet that has eaten cannabis is a problem many owners find awkward to bring up. The product may be legal where you live, or it may not; either way the animal needs help, and the best help depends on honest information. This guide covers what THC does to dogs and cats, what the Merck Veterinary Manual says about onset, signs and dose ranges, why edibles are riskier than they sound, and what to tell the vet or helpline. It is general information from a website editor, not veterinary advice.

Why this is a pet problem at all

Cannabis products are more widely available than they once were, and they are more varied: dried flower, edibles, gummies, baked goods, oils, vape cartridges and concentrates. Dogs are the animals most often exposed because they eat things off tables and out of bags. The Merck Veterinary Manual notes that plant material averages 4 to 20 percent THC, hash and hash oil 20 to 50 percent, and concentrates ("dabs") can reach 80 to 90 percent. It also says product potency is inconsistent and unregulated, which makes toxic doses hard to estimate. Edibles add a further layer: the label may state milligrams of THC per piece, but a bag may contain dozens, and a dog does not stop at one.

What THC does

THC is the main psychoactive compound of cannabis. In dogs and cats it acts on the nervous system and, in the manual's words, common signs are lethargy, ataxia (wobbliness) and vomiting. Others include urinary incontinence, sensitivity to motion and sound, trembling, a slow heart rate, agitation, widened pupils and changes in body temperature. Less common are low blood pressure, slowed breathing, a fast heart rate and seizures. Owners often describe a dog that is "glassy-eyed", swaying, dribbling urine and startled by sudden noise. Merck reports that, in Pet Poison Helpline cases, the most common signs were lethargy (30 percent), ataxia (21 percent) and vomiting (15 percent).

Onset and duration

Merck says signs begin within minutes if inhaled and 1 to 2 hours after ingestion, and up to 4 hours in fasted dogs. Cornell University's canine health information gives a wider range: from about 30 minutes to several hours after exposure, with signs persisting for up to 72 hours. In a published series of 213 dogs (Janczyk and colleagues, 2004), most cases fell within 1 to 3 hours of ingestion. Merck states that signs are usually self-limiting, resolving within 1 to 3 days, and that dogs excrete about 80 percent of THC within 5 days; the biological half-life is around 30 hours. Pharmacokinetic detail aside, the practical point is that an affected animal can be impaired for a day or longer, and a dog that is wobbly may fall down stairs, injure itself or choke on vomit.

Published dose ranges for dogs

Merck gives these approximate THC levels in dogs:

• Mild signs from about 0.3 to 0.5 mg/kg of THC.
• Moderate signs above 2 to 3 mg/kg.
• A probable oral lethal dose above 3 to 9 g of delta-9-THC-dominant plant material per kg, with lethality described as extremely rare.

Worked example, with invented numbers: an edible labelled 10 mg THC per gummy, and a 10 kg dog that eats 5 gummies. 5 × 10 = 50 mg. 50 ÷ 10 = 5 mg/kg, which is above the moderate-signs level. A 30 kg dog that eats the same 5 gummies gets 50 ÷ 30 ≈ 1.7 mg/kg, within the range between mild and moderate. For plant material, the arithmetic depends on THC percentage: 1 g of flower at 20 percent THC contains about 200 mg of THC (1 g × 0.20 = 0.2 g = 200 mg), so even a small piece can exceed the mild-signs level for a small dog. Our cannabis THC reference does these calculations, though the real THC content of a product is often uncertain. Merck gives no equivalent dose figures for cats in our source; the manual says cats' signs are similar, and an exposed cat should be treated as an emergency call.

The hidden hazards in edibles

An edible is not just THC. Chocolate is a common base for cannabis products, and Cornell's guidance advises identifying other toxic ingredients, such as chocolate or xylitol, from the packaging. Chocolate brings its own methylxanthines (see our chocolate guide); sugar-free gummies and baked goods may contain xylitol (see xylitol sources); raisins may be baked into brownies or cookies (see grapes and raisins). Merck notes two published canine deaths involved baked goods made with cannabis butter, a concentrated product, though the cause of death was not reported. So the right question to ask about an edible is "what else was in it?" as well as "how much THC?".

Be honest with the vet

People sometimes hide that a pet ate cannabis, out of embarrassment or fear of legal trouble. Cannabis laws differ widely: the manual notes that the DEA lists marijuana and THC as Schedule I drugs and that state legal status varies, while in the UK cannabis is a controlled drug. We are not lawyers and cannot advise on your legal position, but the veterinary reason to tell the truth is strong. There is no reliable point-of-care THC test for animals; Merck notes that human urine drug screens give false negatives very commonly in animals, probably because many metabolites are not detectable in dog and cat urine. Without a history, signs like wobbliness, drooling and slow heart rate may be mistaken for a neurological, toxin or metabolic problem, and the pet could be subjected to unnecessary, costly tests or the wrong treatment. A clear statement of what, how much and when lets the team treat the right thing. Poison helplines exist to help you with the animal.

Hemp and CBD products

Merck notes that the 2018 Farm Bill removed hemp-derived cannabis from the definition of marijuana, and that the FDA has not approved any THC, THC:CBD or full-spectrum products for veterinary use. Products sold as CBD oils for pets are not equivalent to a veterinary-approved medicine, and some contain measurable THC. A "pet CBD" bottle that a dog gets into is worth a call, with the label and strength at hand. Do not give your pet cannabis products for pain, anxiety or sleep without a vet's guidance.

What to do if your pet has eaten cannabis

1. Keep the animal calm and safe: away from stairs, water and traffic, in a quiet, dim place. Stay with it.
2. Collect the packaging, product name, THC strength and number of pieces, and the time of ingestion. Check for chocolate, xylitol, raisins or other ingredients.
3. Weigh the pet or use a recent weight.
4. Call a vet or poison service now. Merck says decontamination, such as inducing vomiting or giving activated charcoal, is only considered within about 1 hour of ingestion and in clinically normal patients, which is another reason not to wait. Do not try it yourself; see our first-hour guide.
5. If the animal is very drowsy, cannot stand, is vomiting or seizing, go straight to an emergency vet. Keep it on its side with its head level if it is unresponsive, and phone ahead.

Merck describes supportive care as the main treatment and says most patients recover well; more intensive measures are reserved for large exposures, concentrates or severe cases. The details are for a vet, and we do not describe drugs or doses.

Why small pets and cats need extra caution

The dose per kilogram climbs fast as body weight falls, which is why a single gummy that barely affects a Labrador can put a small dog or a cat into a difficult state. Merck gives cat pharmacokinetic figures (peak blood level about 2 hours, initial half-life about 1.6 hours) that suggest absorption is quick, but it does not provide an owner-friendly dose table for cats, so there is no number we can responsibly offer you. The sensible reading is that any cat exposure deserves a call. Impaired animals can also become dehydrated or chilled, and a cat that hides in a cupboard while affected is harder to monitor. Check on any exposed pet regularly, and do not let it go outdoors until fully recovered.

Prevention

Treat cannabis like any other medicine or alcohol in the house. Keep it in a closed container inside a closed cupboard or locked box, not in a bag, drawer or on a table. Keep edibles in their child-resistant packaging, and pick up every piece, not just the packet, after use. Never leave edibles or vape cartridges where a dog can reach them. Ask visitors to keep their bags up off the floor, particularly for pets that scavenge. Be careful with second-hand smoke or vapour in small rooms, since Merck notes onset within minutes if inhaled. Our pet-proofing checklist covers the bedroom and living room, and the human medicines guide covers other things in handbags.

If your pet has had cannabis

This article is general information, not veterinary advice. Contact a vet or poison service immediately: ASPCA Animal Poison Control +1 888-426-4435, Pet Poison Helpline +1 855-764-7661 (fees may apply), or in the UK your own vet or the Animal PoisonLine on 01202 509000 (charges may apply). If your pet is unresponsive, having seizures, struggling to breathe or cannot stand, go to an emergency vet immediately.

Sources

• MSD/Merck Veterinary Manual: Toxicosis in dogs and cats from tetrahydrocannabinol (THC)
• Cornell University College of Veterinary Medicine: Cannabis THC intoxication in dogs
• ASPCA Animal Poison Control: What to do if your pet is poisoned
• PDSA: Animal PoisonLine

Not veterinary advice. The authors are not veterinarians. If your pet may have eaten something toxic, call your vet or a pet poison line now: ASPCA Animal Poison Control (US) +1 888-426-4435, Pet Poison Helpline (US/Canada) +1 855-764-7661, Animal PoisonLine (UK) 01202 509000. Fees may apply. Spotted a mistake? Email huhuwen09@gmail.com with the page address and we will check and correct it.