Marijuana is the dried part of the cannabis plant (cannabis sativa). It has been used for over 2000 years as herbal medicine and to make products such as rope and paper products. Today it's mainly used recreationally or medicinally whereas people inhale it (smoke or vapour products) or take edibles that contain cannabis oil for medical reasons.

Cannabis is made up of many chemicals called cannabinoids. Tetrahydrocannabinol (THC) is a cannabinoid that has psychoactive effects. Cannabidiol (CBD oil) does not have any psychoactive effects. THC can be used to help people with appetite problems or nausea such as with chemotherapy treatments. Compounds called CBD can also help with medical conditions without being psychotropic.

Although cannabis use is not new, recreational marijuana use is up. Until recently, marijuana was legal in Canada and some states in the US, but there were strict controls over who could buy it and why. Legalizing drugs such as marijuana widely has led to an increase in accidental exposure in pets. As veterinarians, we expect to see a rise in pets accidentally ingesting cannabis or marijuana. In many of these cases, dogs have been exposed; this has been known to happen when the owners are not careful with the placement of their supplies.

How do Dogs and Cats Become Poisoned or Intoxicated?

Cats and dogs can be intoxicated or poisoned by cannabis in various ways. This usually happens when they are left alone with someone who is smoking marijuana, eating edibles containing it, or if their curious nature leads them to eat something that contains the drug. Because of the number of cannabinoid receptors in dogs, marijuana affects them differently than people. A small amount of cannabis or marijuana can lead to toxicity for both dogs and cats.

It is very important that you provide as much information as possible to your veterinarian. Different types of exposure require different treatments. Dogs that have cannabis intoxication because of second-hand smoke and treated very differently than those dogs that have ingested a cannabis product orally.

What are the effects of Cannabis on dogs and cats?

Cannabis is just one of several drugs that have a specific effect on the brain. Cannabis enters your pet's body when they inhale (second-hand) or ingest it and will bind with certain receptors in your brain, altering normal neurotransmitter function. There are a few routes that THC takes when it enters your body. As THC is fat-soluble, it is easily stored in fatty tissue, like the liver, brain and kidneys before being excreted from the body. The majority of THC is eliminated through feces while a small percentage exits via urine - so for effects to wear off, it has to be metabolized and excreted out.

What is the difference between CBD and Marijuana in Regards to Toxicity for Pets?

The two main cannabinoids within the cannabis plant are THC and cannabidiol (CBD). CBD and hemp products without THC appear to be well tolerated by dogs and cats and have a place for their use. More studies will need to be performed to determine appropriate therapeutic dosing and safety margins. Marijuana however contains THC which can be dangerous and toxic to pets when exposed. While rarely fatal, prompt treatment is beneficial and this is why we feel it is important for you to understand some of the symptoms your dog or cat may show after ingesting THC or marijuana.

What are the clinical signs of cannabis poisoning or intoxication?

Clinical signs or symptoms of cannabis intoxication in dogs and cats can vary based on how much and when the THC was ingested, but the most common and predictable side effects are related to the neurological system:

  • Mental dullness/depression
  • Vomiting
  • Increased urination/urinary incontinence
  • Tremors
  • Ataxia (imbalance)
  • Dilated pupils
  • Hypersalivation

How is cannabis intoxication treated in dogs and cats?

If you witness your pet ingesting a product containing THC or marijuana, call your veterinarian immediately for instructions on how to induce vomiting. Vomiting can be induced within an hour or two after ingestion. If symptoms are already noticed, contact your veterinarian for advice as they will likely recommend supportive care within the animal hospital. As there is no antidote available, this would include intravenous fluids, anti-vomiting medication and activated charcoal to help bind any residual toxins within the gastrointestinal tract that have yet to be absorbed. Fortunately, with proper supportive care, most dogs can make a full, complete recovery within a couple of days.

It is important to be aware of cannabis intoxication in dogs and cannabis poisoning in dogs. Second-hand cannabis smoke can make it difficult for your dog’s lungs, while an ingested cannabis product may affect their neurological system. If you see signs that your dog has been exposed to marijuana, contact a veterinarian immediately or induce vomiting if possible within one or two hours after ingestion. Cannabis toxicity is rarely fatal but because there is no antidote available, supportive care will need to be administered until the toxin leaves the body naturally through feces and other bodily fluids such as urine. With proper treatment from your veterinarian, most dogs can recover completely within just a few days!