Marijuana does not affect dogs in exactly the same way that it does humans, though some shared symptoms may occur such as sleepiness, confusion or diminished motor skills. Ingested marijuana has the potential to be seriously harmful or even fatal to dogs, however.
Dogs that ingest large amounts of marijuana in the form of edibles rich in THC, such as pot brownies or butter, may be at risk for serious health problems. Dogs can often tolerate smaller doses, such as a single cookie or brownie, but may vomit or show other signs of distress. In general, experts suggest that marijuana should be kept away from dogs for their own safety.