Help, the Dog Ate My Medicine!

Posted July 28th, 2011 by Lisa Cass, DVM

Marijuana Ingestion by Dogs and Cats: What you need to know

By Lisa Cass DVM

So you just came home to find your pooch has been counter-surfing and decided to snack on your MMJ edibles. What’s the best course of action?  Just dim the lights and put on some Allman Brothers?  It won’t really help your dog but it might make you feel better while you call the vet.

My first experience with a dog that had eaten marijuana was as a student in vet school, when a couple brought in their two year old black Labrador, appropriately named Chewy. Chewy had glassy eyes and stumbled in to the exam room, where he promptly lay down and began panting heavily. When I questioned the owners to find out what was going on, they were nervous and evasive when I asked if he could have gotten in to something.  At one point during the exam, Chewy rose and began barking at the computer monitor in an agitated fashion, fell to one side, and lay down again.  His physical exam revealed dehydration, a rapid heartbeat, dilated pupils, difficulty walking (called ataxia), and he vomited when I palpated his abdomen.

As I recommended hospitalization and prepared to take Chewy back for testing, the man told me that while they had been on a hike, and Chewy had come running out of the woods with a baggie in his mouth.  Aha!  Now I had something to go on.  I kind of doubted the baggie in the woods story, but at least I got the information I needed to help Chewy.

These days, with decriminalization and legalization of medical marijuana in Colorado, hopefully conversations, or rather non-conversations like the one I had with these clients will be a thing of the past. The important thing to remember is to be completely honest with your veterinarian if you think your dog may have eaten marijuana. I’ve never met a vet that would turn someone over to the police for something like this; more likely the story might become an entertaining cocktail party conversation at some point, with names changed to protect the innocent of course.

THC is rapidly absorbed after dogs ingest marijuana, with symptoms usually beginning to develop within about 30-90 minutes after ingestion.  While it is possible to induce vomiting if you catch your dog in the act, inducing vomiting is useless after about an hour and should NEVER be done if your dog is already exhibiting symptoms. The reason for this is that marijuana can cause excitement or depression of the nervous system, and induction of vomiting can also excite the nervous system and exacerbate the problem rather than helping to alleviate it.   In one study that reviewed the cases of 431 dogs that had ingested cannabis, only 14 (6%) were asymptomatic (1).

Common signs seen in dogs that have eaten cannabis include tachycardia or bradycardia (rapid or slow heart rate), disorientation, ataxia (difficulty walking), depression, tremors, seizures, dilated pupils, hypersalivation, weakness, and hypothermia. About a third of dogs have vomiting or diarrhea.  The severity of these signs increases with the amount that has been consumed. Some of these signs may sound a little scary: they are.

So the main message here is that if you think your dog has eaten cannabis, call your veterinarian.

The good news is that death from marijuana intoxication is quite rare, and the lethal dose for dogs and cats is approximately 3g/kg. (2)  Not every dog will need treatment, but some definitely will.


Yes, they are subject to the same type of intoxication as dogs, however, cats are much less likely to snack on marijuana.  My first and only feline patient treated for cannabis consumption (and apparently ate a large amount of it right out of a baggie) has shown no long term effects from his little party, but then again, he was weird to begin with.  Cats present a bit more concern than dogs when eating any kind of plant material. Because they are strict carnivores, cats lack the enzymes needed to digest many plant foods, so any plant snacking by cats, including house plants, can be cause for concern.

Edibles with chocolate

MMJ edibles containing chocolate present a different concern because chocolate itself is toxic to dogs. Chocolate contains methylxanthine alkyloids, primarily caffeine and theobromine, that can cause excitement of the nervous system and even seizures in dogs. Chocolate poisoning is one of the most common poisonings in dogs, and the nervous system excitement caused by chocolate plus the nervous system depression caused by marijuana can be a bad combination, especially in small dogs.

Calling your Veterinarian

Your veterinarian will want to know what the dog ate, how much he ate, and how long ago he ate it, as well as how much the dog weighs.  As I mentioned before, many people are reluctant to call the vet due to a concern about being judged, or in the case of potential illegal substance ingestion, concern about the police being involved. If you are worried about being judged, please find a new vet. Vets are, first and foremost, concerned about keeping your pet healthy, not about judging your lifestyle.  People have told me they are reluctant to call the vet because they think the vet will tell them to bring their pet in for an exam.  Yes, we will absolutely tell you to bring your pet in. Things are not always what they seem, pets cannot tell us what happened and how they feel, and a physical exam is the best way for us to evaluate your pet’s health.

The most important thing you can do is keep your medicine up and out of reach of the sensitive noses of curious four legged family members. But if it does happen, stay calm, gather as much information as you can, and seek help.



1)       Sturgeon, K and Campbell, A. Dopey Dogs- A Review of Cannabis Exposures in Canines,  Clinical Toxicology, Vol 46, no 5 p 384, June 2008.

2)       Luiz JA and Heseltine J. Five Common Toxins Ingested by Dogs and Cats, Compendium, Vol 30 No 11, Nov. 2008.

copyright 2011 Lisa Cass DVM

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