Marijuana Toxicosis in Animals

Beginning in 2019, the ASPCA's Animal Poison Control Center (APCC) noted a large jump in calls about pets eating weed (marijuana.) In fact, in the first couple of months of that year, APCC reported a 765 percent increase over a 10-year period.

With more states legalizing marijuana, this trend is likely to continue.

And APCC Medical Director Dr. Tina Wismer noted that the abundance of edibles makes marijuana more enticing to dogs since they often smell and taste like regular baked goods. Cats, on the other hand, are more attracted by marijuana in its bud form.

Exposures in indirect ways have also been reported, including consumption of human feces or careless disposal of marijuana remnants in public locations, to name a few. 

Marijuana is the dried material of the plant Cannabis sativa. Herbal preparations contain over 400 compounds, including 60 cannabinoids. The most potent psychoactive cannabinoid is THC (delta 9 tetrahydrocannabinol). 

Signs of Exposure

Signs that an animal has been exposed to marijuana generally include depression, ataxia, mydriasis, bradycardia, hypothermia, and urinary incontinence. While many toxins can cause ataxia and lethargy, urinary incontinence is not as common and can be a clue to exposure. Pets exposed to marijuana may exhibit other signs such as agitation and tachycardia. Seizures and coma, although not common, may occur as well. 

Without observation of exposure (or the owner admitting what happened), an over-the-counter urine drug screen may be a diagnostic tool for veterinarians. However, this has drawbacks since dogs produce different metabolites in their urine than humans, and false negatives are common with pets exposed to cannabis.

Treatment for marijuana is usually symptomatic. Decontamination is often unnecessary and may do more harm than good. Due to CNS depression, aspiration may be a major concern if emesis is induced or activated charcoal is given.

Fortunately, most marijuana exposures are not serious. Clinicians should attempt to obtain information regarding how much and what form was ingested (for example, butter may contain a higher concentration of THC due to THC's lipid-soluble nature).

Consider the pet's current physical findings to make the best judgment on what may or may not be needed for the patient. Home monitoring may be feasible in some cases. However, young and/or small patients may have more problems with hypothermia and thus need to stay in hospital. In more severe cases, lipid emulsion therapy may be beneficial due to THC's high lipid solubility.