Dogs and cats are generally known to show signs of marijuana poisoning one to three hours after exposure. These symptoms usually last between 18 and 24 hours, but can persist up to three days. The euphoric effects and other effects of Tetrahydrocannabinol (THC) usually last 18 to 24 hours in dogs. As THC is highly toxic to dogs, they cannot simply “fall asleep”.
If you observe any of these signs, it is important to contact your vet immediately. With the right treatment, dogs usually make a full recovery within a day or two. Physical signs of THC toxicity include a slow or rapid heart rate, altered blood pressure, and decreased breathing rate (respiratory rate). Lethargy and changes in body temperature can also be observed.
Fortunately, these side effects are usually short-lived, but they can still be dangerous and make your pet very uncomfortable. THC is the potent psychoactive substance found in marijuana and dogs have a much more severe reaction than humans when exposed to it. Dogs can experience toxicity when ingesting the plant directly, inhaling marijuana smoke, or consuming baked goods or other foods containing marijuana. Although there are tests to determine the level of THC in the urine, the results take time and are not practical.
The main difference between THC and Cannabidiol (CBD) is that THC causes psychotropic effects and has a moderate level of toxicity, while CBD is not psychotropic and many researchers consider it to be non-toxic or have limited toxicity. Many pet owners are unaware that marijuana is toxic to their dogs, especially with the recent research on the various benefits that marijuana can offer humans. To help prevent toxicity, it is important to keep marijuana edibles out of reach of pets in tall locked cabinets or locked drawers when not in use. For example, ingesting a “pot brownie” requires different treatment than inhalation, as eating the brownie requires treatment for the toxicity of cannabis and chocolate, while inhalation may require additional treatment for respiratory irritation. This is because your dog's body breaks down THC differently than yours does.
First, signs of toxicity may not appear until after the drug has been absorbed into the system. Your veterinarian may also choose to administer activated charcoal which will help reduce the amount of THC absorbed. When your dog is exposed to THC, it is absorbed by the intestine and stored in bile, a liquid produced by the liver. Medically, THC is used to try to relieve muscle spasms caused by multiple sclerosis, nausea caused by chemotherapy, weight loss in patients with AIDS, seizure disorders, and Crohn's disease. Cannabis is considered to have a high margin of safety for people; however, not all people, and certainly not all pets, follow a single pattern of poisoning.
THC can be detected in blood or urine but diagnosis is usually based on clear clinical signs as well as the owner's story. THC is metabolized in the liver and most (65-90%) is excreted in faeces while a small percentage (10-35%) is eliminated through the kidneys.