Marijuana Toxicosis in Pets

Laurie Anne Walden, DVM

Research-grade Cannabis sativa plant. Photo credit: NIDA/NIH (US government work).

Animal exposures to marijuana have increased dramatically in recent years. As more states legalize medical or recreational marijuana for human use, more pets are likely to have access to cannabis products.
 
To keep things clear, here are a few terms used to describe cannabis products:

• Cannabis sativa is the plant that produces marijuana and hemp. Cannabis plants contain lots of different natural compounds called cannabinoids.
• Tetrahydrocannabinol (THC) is a cannabinoid. It’s psychoactive, meaning that it causes a “high.”
• Cannabidiol (CBD) is a cannabinoid that is not psychoactive in its pure form.
• Marijuana is cannabis with a THC concentration of greater than 0.3%.
• Hemp is cannabis with a THC concentration of 0.3% or less.
• Synthetic cannabinoids (K2, “spice,” “potpourri,” etc) are manufactured compounds that mimic the effects of psychoactive cannabinoids or illegal drugs. These compounds are sprayed onto dried plant material or used in vaping devices. Synthetic cannabinoids are more toxic than natural cannabinoids. Products containing synthetic cannabinoids are sometimes also laced with other harmful substances.

 
Sources of Exposure
Edible products account for most THC exposures in pets. Edible products made with butter or oil infused with medical-grade marijuana have a high concentration of THC. Edible products can also contain other ingredients, like chocolate and xylitol, that are dangerous for animals.
 
Cannabis plants are also a risk for animals. The THC content of cultivated C sativa has increased over time and varies among plants, so it’s hard to know just how much THC an animal that eats part of a cannabis plant or inhales the smoke has received.
 
Vaping devices containing CBD, THC, or synthetic cannabinoids have caused toxicosis in animals. Animals have also been poisoned by eating marijuana in discarded cannabis products and—this one is gross—human feces.
 
CBD products have been reported to cause poisoning in animals. It’s possible that the toxic effects were caused by contamination with THC or another substance, not the CBD itself, but the effects of CBD on animals are still being investigated. Another concern with CBD is that it might interact with prescribed medications, possibly affecting liver function.
 
Signs
Marijuana toxicosis makes animals sick but is rarely fatal. However, 2 dogs have died after eating baked goods containing medical-grade marijuana butter.
 
Signs of poisoning start within a few minutes to several hours after exposure, depending on the type of exposure. These are some of the signs of marijuana toxicosis in animals:

• Incoordination
• Lethargy
• Dribbling urine
• Vomiting
• Increased sensitivity to touch, motion, or sound
• Tremors
• Agitation
• Drooling

 
Exposure to THC or synthetic cannabinoids can also cause changes in heart rate, inability to regulate body temperature, aggression, seizures, and coma.
 
Diagnosis
Over-the-counter human urine tests for marijuana don’t work well in dogs and tend to return either false-positive or false-negative results. The diagnosis of marijuana toxicosis is usually based on clinical signs, although many diseases and other toxins can cause the same signs. Knowing that an animal could have been exposed to marijuana certainly makes the diagnosis easier, but owners aren’t always willing to tell a veterinarian that their pet had access to a cannabis product.
 
Treatment
Whether an animal with marijuana poisoning needs to be hospitalized depends on the severity of the signs. Treatment is mostly supportive care, with medication used as needed to treat specific problems (like heart rate abnormalities). Inducing vomiting can be unsafe, so an animal that has eaten a cannabis product might need to be sedated so the stomach can be emptied through a tube.
 
The prognosis is usually good for animals with marijuana poisoning. The risk is higher for animals exposed to medical-grade marijuana products or synthetic cannabinoids.
 
Sources

• Cannabis in veterinary medicine. American Veterinary Medical Association. 2020. Accessed May 16, 2023. https://www.avma.org/sites/default/files/2021-03/APH-CannabisResources-Report-20201207.pdf
• Marijuana toxicosis in animals. ASPCApro. Accessed May 16, 2023. https://www.aspcapro.org/resource/marijuana-toxicosis-animals
• Meola SD, Tearney CC, Haas SA, Hackett TB, Mazzaferro EM. 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 (San Antonio). 2012;22(6):690-696. doi:10.1111/j.1476-4431.2012.00818.x

 
Image source: https://www.flickr.com/photos/nida-nih/28147221034/in/photostream/

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