Marijuana Toxicity in Dogs


Marijuana toxicity is a growing issue in the USA, especially in states where its use has become legalized. With that potentially on the horizon in Canada, it is important that pet owners be aware of the signs and side effects of marijuana ingestion in their pets.

What is Marijuana?

Marijuana (Cannabis sativa) is a plant that is used both medicinally and recreationally (in humans) for many different properties. Medically it is used to help control chronic pain and nausea, while recreational users tend to enjoy the psychoactive side effects it has on the central nervous system.  The major active ingredient in Marijuana is delta-9-tetrahydrocannabinol (THC). It triggers the release of neurotransmitters: acetylcholine, dopamine, norepinephrine and serotonin, which work on the brain’s frontal cortex and cerebellum. Marijuana can be smoked, vaporized or ingested. The growing concern for veterinarians is the edibles market. Edibles tend to possess a higher THC potency than the natural plant itself, meaning they have a much stronger effect.

Symptoms if ingested by dogs:

Mild cases:

-dramatic response to visual or auditory stimulus

-reddened conjunctiva

-behavioral abnormalities


Moderate to Severe cases:

-Ataxia (impaired walking)


-low blood pressure

-low heart rate



-lack of appetite

-urinary incontinence

*Coma and death have been reported in severe cases, but it was also believed that there were other illicit drugs involved

If the ingestion is recent and the patient is mentally aware, inducing vomiting is the first line of defence. If warranted, charcoal may be given to help stop the absorption of any residual drug in the stomach. In the majority of cases, IV fluids and gastro protectants are enough to support our canine patients through the effects. In severe cases, thermoregulatory support may also be required.

The majority of dogs make a full recovery within ~24 hours without any long term effects.


Written by Caitlin Johnston, RVT