Marijuana Toxicity in Pets

Marijuana Toxicity in Pets

On May 17, 2016, Pennsylvania’s Act 16 went into effect which will allow legal use of marijuana in the state for medicinal purposes.  With increased human usage comes increased potential for animal exposure.  Many other states have had similar laws in place for medical marijuana use as well as a few states allowing recreational use.  States such as Colorado who have had laws allowing for marijuana use for many years have seen as much as a four-fold increase in the number of cases of toxicity in animals. ¹ Exposure may be accidental if a pet accidentally ingests part of the plant or edible item made with chemical compounds from the drug, or, exposure could occur if a pet is intentionally given marijuana for a medical condition though this is not currently legal and there are few studies to support use or provide proper dosing for pets. 

What might we see if a pet ingests marijuana?  First, the active ingredient that causes toxicity is THC or delta-9-tetrahydrocannabinol but other substances in the plant may also contribute.  Ingestion of fresh or dried cannabis leaves is the most common form of exposure, but cannabis compounds may also be found in foods like brownies and in butters and oils.  Pets who ingest marijuana in any form may experience lethargy, stumbling or ataxia, and low heart rate and temperature.   Unique to dogs, urinary incontinence (leaking urine) may occur due to a metabolite that forms when the dog’s body breaks down THC.  This compound is not formed during human metabolism.²   Some dogs may experience hyper-excitability rather than depression or lethargy.  Ingestion of large concentrations of THC such as those found in oils or butters may cause severe neurologic changes including coma and low blood pressure and two deaths have been reported.  Symptoms may occur within thirty minutes of ingestion and can last up to three days.³

There are no good tests for marijuana exposure and symptoms can appear similar to antifreeze poisoning so a good and truthful history is very important in ensuring that pets receive proper treatment if they have been exposed to marijuana.  For many cases of toxin ingestion, inducing vomiting is part of the decontamination protocol; however, the THC in marijuana is a powerful anti-vomiting compound so it may not be possible to make the patient vomit.  Pets experiencing mild symptoms would be expected to recover but may need supportive care with intravenous fluids and monitoring of heart rate, temperature and neurologic state.   In severe cases of TCH toxicity, a treatment called IV lipid emulsion may bind the drug and increase elimination from the body.  Recovery may take several days, especially in severe cases.⁴

With new laws regarding marijuana, the opportunity for pets to be exposed to this drug and its compounds may increase.  If a pet is suspected of being exposed to marijuana, contact your veterinarian or the ASPCA Poison Control Center at 1-888-764-7661 or the Pet Poison Helpline 1-855-764-7661.

This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.  

1, 2, 3, 4—from “Marijuana:  From People to Pets,” in Veterinary Team Brief Volume 4, issue 5 June 2016 pp. 29-38