How dangerous is Cannabis for dogs?

Cannabis Dogs

What is Cannabis?

Cannabis satvia is a plant whose leaves and flowers are processed to be smoked (or eaten) by people for its psychoactive effects.  Cannabis may be called hashish or hash, marihuana or marijuana, ganja, grass, weed or pot, and cannabis cigarettes may be referred to as joints, spliffs or reefers.  The intended effects in people are euphoria, relaxation and altered perception. The main chemical responsible for these effects is called tetrahydrocannabinol, or THC.  

How much Cannabis can hurt a dog?

It appears to have similar effects in dogs as it does in humans but given the size difference and a dog’s lack of discrimination with regards to dose, they can become poisoned from eating any quantity.  At Animal PoisonLine we have had calls about dogs who have been exposed to cannabis in a number of ways:

  • By eating joints
  • By eating brownies or biscuits which have cannabis baked into them
  • By being exposed to second hand smoke (inhalation)
  • By discovering and eating a stash of cannabis in the house

What might happen to my dog after eating Cannabis?

The most common effects in dogs are depression, drowsiness or lethargy. They may also be very wobbly on their feet or unwilling to stand and have a slow heart rate.  The depression may alternate with periods of excitability, agitation, aggression and barking, as dogs can apparently experience hallucinations.

Other effects may include weakness, effects on their eyes (e.g. big pupils, red eyes and light sensitivity), vomiting and drooling. They may be unable to control their bladder and bowels and their body temperature can go either up or down.  In some cases dogs develop twitching or tremors which can lead on to fits.

These effects would be expected to occur within a few hours of eating cannabis and pets may be very poorly for several days after.  Dogs exposed to second hand smoke can develop effects within minutes and recover over a few hours.

When recovering, dogs may experience an increased appetite; in humans this phenomenon is known as ‘the munchies’.

Animal PoisonLine’s Top Tips about Cannabis?

  1. If you think your dog may have eaten some cannabis it is important to seek veterinary help as it can cause serious poisoning, requiring intensive treatment.
  2. It is important you tell your vet what has happened so that they can treat the dog correctly.
  3. Do not try to make them sick as this could make them worse.


If you are worried your pet has eaten something they or been exposed to something they should not have, please call the Animal PoisonLine on 01202 509 000 for advice on what to do next. If your pet starts showing any signs, then take them to your local vet practice immediately for treatment. The sooner they are treated, the better the outcome.