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Marijuana Toxicity in Dogs: Diagnosis and Treatments of Marijuana Ingestion

If you think your dog ate weed, here’s what to do and how long it will last.

Confused dog lying in a field a green
Khaligo / AdobeStock

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You won’t be surprised to learn that marijuana is one of the most common toxins eaten by dogs, especially around college campuses. It’s fairly easy for a dog to get into trouble with this drug (widely referred to as “weed” or “pot”) because it’s so broadly available now that it’s legal in many states. They might be exposed to the effects of weed after eating edibles (baked goods), eating joints (the remains of marijuana cigarettes), after getting into somebody’s weed “stash” (dried plant), or from secondhand smoke. Sometimes dogs can even get into mischief while out on hikes, finding and eating some abandoned drugs.

So, if your dog ate weed, you’re probably wondering how long it will last. The good news is most dogs will fully recover and the symptoms from eating weed don’t last long. But if you think your dog has been exposed to marijuana, they’ll need immediate veterinary attention. Here’s everything you need to know about marijuana toxicity in dogs.

What is Marijuana Toxicity in Dogs?

Let’s start with the basics: Marijuana is the dried leaves and flowers from the hemp plant (Cannabis sativa), which contains the active chemical tetrahydrocannabinol (THC). Marijuana toxicity (sometimes referred to as cannabis poisoning or THC poisoning) is caused by the ingestion or inhalation of the active chemical THC, which can be toxic to dogs, especially in high doses.

When the THC in weed is consumed (or inhaled) by a dog, it is absorbed quickly into the bloodstream. Symptoms can be seen within 30 minutes but may take up to 3 hours after initial exposure. If your dog inhales the smoke, symptoms may appear within a few minutes. A few factors influence the timing of symptoms, including dosage, the dog’s age and weight, and how they were exposed (inhalation vs. ingestion).

As the drug works through the bloodstream, the immediate symptoms begin to disappear quickly. Most pups will make a full recovery within 24 hours. But some effects of THC toxicity may last up to three to four days because the chemical is absorbed into fat.

Diagnosing Marijuana Toxicity in Dogs

While THC can be detected in blood or urine, diagnosis is not generally done with urine tests. Because marijuana toxicity is so common, most vets can make a diagnosis based on the unmistakable symptoms caused by THC and details provided by pet parents.

Symptoms of Marijuana Toxicity Include:

  • Incoordination and Stumbling

  • Lethargy

  • Dilated pupils

  • Slow heart rate

  • Tremors

  • Disorientation

  • Urinary incontinence

  • Agitation

  • Respiratory depression

  • Seizures

  • Coma

More than 95 percent of the veterinary patients seen for marijuana toxicity are dogs, and almost all exposed animals will exhibit neurological signs. The most common clinical signs are stumbling, uncontrollable urine dribbling, drooling, low body temperature, low blood pressure, and an increased response to stimulation. At higher doses, dogs can also suffer from hallucinations with barking or agitation. In particularly bad reactions, symptoms can progress to seizures, low or high heart rates, respiratory depression, and coma. Because of the increased risk of toxicity, dogs cannot simply sleep it off; they should be taken to receive treatment immediately.

Treatment for Marijuana Toxicity in Dogs

If a dog recently ate marijuana (within 30 minutes), your veterinarian may attempt to induce vomiting to minimize the amount of toxin available to be absorbed. However, if it’s been longer than 30 minutes since ingestion, the anti-nausea effects of marijuana usually make the chances of inducing vomiting unlikely.

Some dogs may be able to be treated at home as outpatients. Your veterinarian may elect to administer activated charcoal, which will help reduce the amount of THC absorbed. Subcutaneous fluids are often given to help prevent dehydration during recovery.

But, if symptoms are severe, your pet may need to be hospitalized for supportive care. With supportive care, veterinarians provide intravenous fluids, repeat administration of activated charcoal, general nursing care, and monitoring of temperature, heart rate, and breathing. If higher doses are ingested, some pets require sedation with valium and, in very rare cases, may require mechanical assistance with breathing if their respiration is severely depressed.

Can Dogs Die from Marijuana Poisoning?

Most dogs will fully recover from marijuana toxicity. Compared to many other drugs, the lethal dose of marijuana is extremely high — so it’s rare for a pet to ingest enough to cause death. A dog is at higher risk when eating edibles (such as brownies) containing chocolates, artificial sweeteners like xylitol, and butters or when exposed to high THC concentrations. The takeaway here is that weed is bad for dogs. The effects known as a “high” in people aren’t the same for dogs. Dogs experience stress, feel sick, have unpleasant disorientation and have worse symptoms. If your dog has eaten marijuana or edibles intended for people, they should be taken to the vet immediately.

If you suspect or know that your dog may have eaten marijuana, do not withhold this valuable information from your veterinarian. Your veterinarian is not obligated to report this to any authorities. This information is strictly needed to appropriately treat your pet and avoid unnecessary (and expensive) diagnostic tests.

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Dr. Shea Cox, DVM, CVPP, CHPV

Dr. Shea Cox is the founder of BluePearl Pet Hospice and is a global leader in animal hospice and palliative care. With a focus on technology, innovation and education, her efforts are changing the end-of-life landscape in veterinary medicine.