What Marijuana Toxicity in Dogs Looks like

As laws around humans using marijuana loosen in the United States, vets are seeing more cases of marijuana toxicity in dogs.

THC-laced baked goods are a major culprit in canine marijuana toxicity. By: valtercirillo

Thanksgiving did not go by without some worrisome emergency phone calls and pets getting into trouble.

On Thanksgiving Day, just as we were about to sit down to dinner, I got a call from a frantic pet parent.

Her tiny Chihuahua, Pepe, had been in a little dog fight the day before, and she brought him to my hospital. His very minor wounds were treated, and he received a rabies vaccine. She said Pepe had been fine for about 28 hours until late afternoon on the following day, Thanksgiving.


The Conversation

“My pet was seen at your hospital yesterday, and he’s having a very bad vaccine reaction,” Mrs. Worried said.

“What are his symptoms?” I asked.

“He’s shaking. He won’t walk. He’s closing his eyes.” She began to whimper.

“OK,” I said, “so he was fine all day yesterday and most of today?” Pepe had not been my patient.

“Oh, yes,” she said. “He’s been fine. He just started shaking and wobbling in the last 2 hours. I’m sure it’s the vaccine.”

“Sometimes,” I said, trying to calm her down, “they might be in a bit more pain the day after the fight. Like when you do strenuous work and don’t feel it till the next day. And the little dogs can be very dramatic when they are in discomfort.”

“But I gave him his pain medicine this morning. And he isn’t in pain,” she said defiantly. “I definitely think it was the vaccine.” She began actively sobbing.


Not a Vaccine Reaction

By now, I knew no matter what I said, this person believed her dog was suffering from a vaccine reaction and resented us for giving him the rabies vaccine, even though he was overdue for it.

I cautiously went around the block with her a few times, explaining that his symptoms did not sound like a typical vaccine reaction. Based on how worried she was, I recommended she take Pepe to the emergency hospital. My hospital was closed on Turkey Day, and I was out of town.

Mrs. Worried became more reasonable, and we went over Pepe’s symptoms again:

  • He was lethargic.
  • He wasn’t using his back legs very well.
  • His eyes were half-closed.
  • His head was lolling back and forth a bit.

I told her this sounded neurologic. “Could Pepe have gotten into anything toxic at home?” I asked.

“Oh, no,” she replied vehemently. “He’s 4 pounds and in my arms or watched in the house all the time.”

I suggested, again, that she take him to the ER. They were open 24/7 and close by.

Somnolence and listing to one side are both symptoms of marijuana toxicity in dogs. By: manfredrichter

Tox Screen Positive

In the morning, there was an emergency fax from the ER about Pepe: “Tox screen showed marijuana toxicity. Pepe is recovering well.”

So Pepe was stoned! He had licked some of the THC oil a guest had left on a very low cocktail table.

Honestly, marijuana ingestion did not cross my mind when I was talking to this sober-sounding woman of a certain age. But perhaps it should have. Veterinarians are seeing more and more of these toxicities with the use of medical marijuana on the rise and the decriminalization of pot in many states.

Signs of Marijuana Toxicity

Listed below are the classic signs of marijuana toxicity exhibited by Pepe. Spoiler alert: Pepe did just fine and slept off his party drugs.

  1. Mydriasis. This term describes dilated pupils. Think of that glassy-eyed, dull but staring sort of look when someone is under the influence.
  2. Somnolent. This word is borrowed from human medicine when describing a patient with altered consciousness. Somnolent means the individual can be easily aroused but requires stimulation to stay awake. In other words, Pepe was continually nodding off. Somnolent is the state between lethargy and obtunded (unable to rouse).
  3. Head weaving at rest and listing. Dogs under the influence of marijuana are rolling their heads around and listing to one side or the other when trying to walk (ataxia). In other words, they look like a cartoon drunken sailor.
  4. Dribbling urine. Unlike many other toxicoses, pot almost always makes a pet dribble urine uncontrollably. If a client notices this, marijuana should be high on the list of suspects.


If the person is truly unaware of any drug exposure, there is a quick tox screen available to vets that tests for cocaine, THC (marijuana), opiates, methamphetamines, benzodiazepines and oxycodone. Pepe tested positive for only THC.

Being able to identify the drug helps us in treatment. All in all, ingestion of pot is fairly safe compared to other drugs.

Watch this poor Greyhound endure the effects of marijuana toxicity:


Most dogs who get into some marijuana exhibit Pepe’s symptoms and literally sleep it off. Pepe’s human wanted to take him home that night, and the emergency vet agreed. She was advised to watch him carefully through the night, make sure she could rouse him and call if Pepe could not be woken up.


Boomer, meaning “full-grown kangaroo,” is a great male dog name for dogs who are tough or outgoing.


There are only a handful of reports of dogs actually dying from marijuana, where dogs ate a large amount of good-tasting, THC-laced baked goods and died of choking on their own vomit. These are extremely rare cases where people were also not around to notice the emergency. Even these intoxicated dogs probably could have been saved with medical intervention and support.

Take-home message: There are more marijuana and marijuana products around than ever before, so keep your pets away from them. Assume nothing about visitors. Old Uncle Morton just might have some weed in his coat pockets that may mean a trip to the emergency vet if your pet gets into it.


This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was last reviewed Dec. 13, 2017.

Dr. Debora Lichtenberg, VMD

View posts by Dr. Debora Lichtenberg, VMD
Dr. Debora Lichtenberg, VMD, is a small animal and exotics veterinarian who has split her time between a veterinary practice in Pelham, Massachusetts, and her studio in New York City. Dr. Lichtenberg is a graduate of the University of Pennsylvania School of Veterinary Medicine with 30 years of experience. Her special interests are soft tissue surgery and oncology.

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