Marijuana Effects on Dogs: funny or fatal?

Marijuana poisoning in dogs is actually not that rare in general and you won’t be surprised to hear that marijuana poisoning becomes even more common in an area when marijuana goes from illegal to legal.

CBD oil is all the rage at the moment, and is actually something that I’ve discussed before in my article: the facts about CBD oil in dogs.  It comes from the cannabis plant and is felt to be really safe so you might well be asking just how dangerous is marijuana?


Is marijuana poisonous to dogs?

Well, marijuana contains a lot of different substances with the most dangerous one being THC.  It is this THC which is toxic and has psychotropic effects, acting on the brain. Thankfully, even though this has toxic effects, it actually takes quite a lot to cause serious poisoning in dogs.

The risk of poisoning due to smoke inhalation is absolutely tiny. Really all reports of poisoning are due to a pet eating marijuana with 96% of cases being dogs and only 3% being cats.  The risk of poisoning in cats is the same, they just don’t eat it as often.

How much marijuana will kill a dog?

The minimum lethal dose, the amount that could kill a dog, is 3g of THC per kg body weight.  The average marijuana cigarette contains about 150mg of THC meaning that a 5kg or 10 pound dog would need to eat 100 cigarettes for a fatal poisoning to occur.  So this situation is pretty unlikely to cause problems.

Don’t think that marijuana can never cause problems though. If a dog gets into a large supply of consumes something like more concentrated medical grade THC butter used in baked products there is definitely a risk of serious poisoning and even death.

As with a lot of poisons and toxins our dogs might come across, there is a variation in how each individual is affected.  A small amount of marijuana may affect one pet a lot more than another so you can’t be too careful.

Marijuana effects on dogs: signs of poisoning

The marijuana effects on dogs and signs of poisoning are numerous and come about through the drugs effects within the brain as well as the body as a whole.  After eating marijuana, the signs of poisoning will typically start to develop within about 60 minutes.

Mild cases of poisoning will be seen as lethargy, a change in the way a dog responds to visual and noise stimulation, behavioral changes and their gums may become quite red.

If a more toxic dose is eaten then excessive salivation might develop, the pupils will dilate, vomiting may start along with diarrhoea, your dog might start to urinate uncontrollably and muscle tremors will also develop.  In fact, in 99% of Marijuana poisoning cases there are nervous, neurological signs whereas only 30% will develop intestinal symptoms.

A higher dose again might result in them becoming very unsteady on their feet, their blood pressure will drop and hypothermia can develop, the heart can slow and as with a lot of other poisons this can eventually lead to seizures, coma and death.

The effects of marijuana on dogs can last for hours or even days. This is because the THC chemical is partly stored in the bodies fat which is then released slowly over a long period of time.

Treatment of Marijuana poisoning

While the likelihood of severe, life threatening poisoning is pretty low as I’ve already discussed, you’ll appreciate from some of the signs of poisoning that in some cases treatment will be needed to prevent any poisoning complications.

Dogs that are severely agitated or hyperactive may need to be sedated. IV fluids may be needed to help control body temperature, support blood pressure and prevent dehydration resulting from vomiting, diarrhoea and excessive salivation. A muscle relaxant or anti seizure medication may be needed in the case of severe tremors or seizures. And in rare life threatening cases the stomach may even need to be emptied, enemas given and activated charcoal administered to remove as much toxin as possible.

Dog eaten marijuana? Tell your vet!

The big difficulty with treatment of marijuana poisoning in dogs is knowing that this is the problem in the first place.  In many cases owners are reluctant to tell their vet that this is what the dog has eaten, instead claiming ignorance. There are human urine tests for marijuana toxicity but these are unreliable in dogs and will often give incorrect results.

It’s important then that you let your vet know your dog has eaten marijuana as without this information it is impossible to differentiate the signs a dog is showing from many other toxins.  Poisoning with different toxins or food items come with a different prognosis and different treatment options. Not knowing the cause of poisoning can mean a dog is given unnecessary treatments, or treated more aggressively than they would otherwise need to be wasting both time and money.

Of your dog has eaten your marijuana supply in any form then let your vet know.  It is important information and should not be withheld.

Poison prevention

As with all poisonings, prevention is better than cure:

  • Keep all marijuana products, including edibles, in high, pet proof cupboards or locked drawers

  • Make sure your pet is not around if marijuana is being smoked and only allowed back in the room once all smoke has cleared

  • Never give your pet marijuana on purpose - it is not funny

Why is CBD oil different?

As I mentioned at the start, CBD oil is a different cannabis extract and does not contain any THC.  CBD oil is considered non-toxic and has several potentially valuable medicinal effects on the body. If you want to learn more about this then make sure you check out my article all about the facts about CBD oil in dogs.

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