Dogs Consuming Marijuana

Cannabis sativa is a member of the Cannabaceae family. Slang terms include pot, weed and Mary Jane, just to name a few. Marijuana, or THC, affects receptors in the brain which alter normal neurotransmitter function. Dogs and cats can be poisoned by marijuana from second hand smoke exposure, or from direct ingestion of marijuana or baked foods (e.g., pot brownies, pot butter, etc.) laced with THC. In dogs and cats poisoned by marijuana, clinical signs can be seen within 3 hours, and include severe depression, walking as if drunk, lethargy, coma, low heart rate, low blood pressure, respiratory depression, dilated pupils, hyperactivity, vocalization and seizures. Vomiting is often seen with dogs despite the “anti-emetic” (anti-vomiting) qualities of THC.

If your dog or cat ate marijuana, call your veterinarian or Pet Poison Helpline immediately for life-saving treatment advice.

Poison type: Illicit Drugs Alternate names: THC, Cannabis, pot, hashish, pot brownies, weed, grass, Mary Jane, reefers, hemp, devil weed, pot butter Poisonous to: Cats, Dogs Level of toxicity: Moderate to severe

Common signs to watch for:

  • Severe depression
  • Walking drunk
  • Lethargy
  • Coma
  • Low heart rate
  • Low blood pressure
  • Respiratory depression
  • Dilated pupils
  • Hyperactivity
  • Vocalization
  • Seizures
Contact the Pet Poison Hotline

As marijuana becomes more of a mainstream topic, the news media is finding new ways to sensationalize their coverage. One topic that has resurfaced lately is dogs and marijuana—specifically, is pot good or bad for them? There is a lot of misinformation out there about canines and cannabis, leading NBC News to report “Marijuana poisoning on the rise in pets.”

Can marijuana poison your dog? We’ve been taught that marijuana is non-toxic to humans, but is it safe for dogs? Chocolate, raisins, grapes, garlic, onions, avocado, and macadamia nuts are delicious to us, but can range from sickening to life-threatening for dogs. And while everything more evolved than a sea squirt has an endocannabinoid system, can human-level quantities of weed overload a small dog’s system?

In the aforementioned NBC News story, Tina Wismer, the director of the Animal Poison Control Center explained, “Animals don’t react the same way as humans. Without treatment, dogs can go into comas and die.” 

Wismer singled out medicated edibles with high THC concentrations as most dangerous to canines, especially if combined in chocolate brownies or raisin cookies.

A 2012 study published in the Journal of Veterinary Emergency and Critical Care followed 125 dogs in Colorado that presented marijuana ingestion from 2005-2010. Authors concluded, “Ingestion of baked goods made with medical grade tetrahydrocannabinol butter resulted in 2 deaths.” According to the Coloradoan, the two dogs died when they asphyxiated on their own vomit. Sad, to be sure, but can we call that a marijuana toxicity?

TheColoradoan also spoke with Ashley Harmon, a veterinarian at Fort Collins Veterinary Emergency and Rehabilitation. She says she’s seen more cases of people bringing in dogs who’ve ingested marijuana since it was legalized in Colorado. She also says she’s seen two smaller dogs die from marijuana ingestion, one who ate a pound of pot brownies and another who ate a pound of pot butter.  But was it the marijuana that harmed the dogs, or the ingredients in the edibles? 

In 2013, researchers writing in the journal Topics in Companion Animal Medicine wrote, “The minimum lethal oral dose for dogs for THC is more than 3 g/kg. Although the drug has a high margin of safety, deaths have been seen after ingestion of food products containing the more concentrated medical-grade THC butter.”  

But in 1973, scientists writing for the journal Toxicology and Applied Pharmacology noted “In dogs and monkeys, single oral doses of Δ9-THC and Δ8-THC between 3000 and 9000 mg/kg were nonlethal.” 

So, 40 years ago, 3 to 9 grams THC per kilogram of body weight was non-lethal to a dog, but last year, 3 grams THC per kilogram of body weight is the minimum lethal dose. Confused yet?

Consider that in those studies, that’s 3 g/kg of THC given orally, not pot itself. A 2004 review published in the Journal of Veterinary and Human Toxicology looked at 213 incidents where dogs ate actual pot from 1998-2001. 

“The marijuana ingested ranged from 1/2 to 90 g,” the scientists wrote. “The lowest dose at which signs [of distress] occurred was 84.7 mg/kg and the highest reported dose was 26.8 g/kg.” They found that even with a dog eating almost an ounce of ganja per kilogram of its weight, “All followed animals made full recoveries.”

In terms of pure THC injected into dogs rather than eaten, researchers in 1983 found “the dose of THC which kills 50 percent of animals (LD50) when administered intravenously is … 130mg/kg in the dog.” 

For comparison’s sake, pure synthetic THC Marinol pills that are prescribed to humans come in 2.5mg, 5mg, and 10mg oral dosages and the THC you’ll get in a package of Colorado medicated edibles ranges from 50mg to 125mg.

So, can marijuana kill your dog? Technically, yes, but realistically, probably not. Your dog would have to eat a pound or more of strong pot or edibles, and be a smaller-sized dog, and you’d have to ignore its symptoms, and the dog would have to pass out and choke on its vomit, or in the case of a chihuahua in New Zealand, experience hypothermia when the same blood vessel dilation that makes your eyes red makes the dog radiate away all its body heat. 

Numerous veterinarians have written about the possibility of coma and death in rare cases from marijuana ingestion, though they all note that most dogs will recover if given proper care. We needn’t overreact to the topic of dogs and marijuana, as there is a promising future in veterinary medical cannabis. Just be sure to get in the habit of keeping your marijuana out of reach of your pets.

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