A Cautionary Tale Regarding Marijuana and Your Dog

Carol M. Harris UW-AAB, Michael E. Harris UW-AAB, Ph.D.

A while ago, a client related an incident requiring a trip to a Veterinary emergency clinic. She was walking with her dog in the Sorrento Valley area and noticed that the dog had found, and was chewing on, something from under a bush. She was able to get her dog to drop it, decided it was nothing, and walked on. After a while she saw that the dog was still chewing on something, pulled it from the dog’s mouth, thought it was plant debris, and continued on. By the time she and the dog returned home, the dog had become disoriented and incontinent. She rushed the dog to an emergency clinic, where the dog was diagnosed to be suffering from acute marijuana intoxication. With supportive therapy, her dog recovered.

With the legalization of recreational marijuana, such episodes are becoming all too common with some veterinary clinics reporting that they are treating 3 or 4 dogs per week for acute marijuana intoxication. Carelessly stored stash bags, laced foods and enhanced/concentrated products pose special health risks for dogs. Even second-hand smoke is toxic to dogs.

There are about 400 identified chemicals in marijuana, with delta-9-tetrahydrocannabinol (THC) being the principle psychogenic agent.

THC exerts its effect by binding to a biomolecular site in the brain, known appropriately as the cannabinoid type 1 receptor, or cb1 for short. The cb1 receptor is found in various areas of the central nervous system (the neocortex of the brain, the hippocampus where memory is involved and the cerebellum controlling balance and motor-coordination) and is concerned with the modulation of several important neurotransmitters, including norepinephrine, serotonin (5-HT), acetylcholine, dopamine (the so-called reward neurotransmitter), gamma a mino butyric acid (the major inhibitory neurotransmitter involved with impulse control), and L-glutamate (involved with learning and memory). Cb1 can be bound by the naturally occurring cannabinols in the body, called endo cannabinols, or by THC or related synthetic compounds. The binding of a cannabinol with this receptor, reduces the release of some of these important neurotransmitters, and promotes the release of others.

Very little is known about the effects of marijuana on dogs or toxicity levels. The cb1 receptor is found in the cerebellum (an area which controls coordination of movement) and the brainstem (where respiration, among other things, is controlled) [1]. The current belief among veterinarians is that the effects are somewhat like that in humans and are moderate to severe and can be life threating. The level of toxicity depends upon age and the size of the dog. Lethargy, panting distress, poor coordination, low blood pressure and incontinence have been observed. If you suspect that your dog has ingested a marijuana product, or part of device for its consumption, get it to a veterinarian immediately. Its life may depend on it.