Many people believe that medical marijuana has been a great success, but because of the legalisation vets are seeing a massive spike of dogs entering hospital with symptoms of staggering, acting lethargic, vomiting and being overly sensitive to sound and light.
The symptoms essentially mean that dogs are having the equivalent of a "bad trip".
"They basically have lost a lot of their fine motor control, they have a wide-based stance and they are not sure on their feet," Dr Debbie Van Pelt of the Veterinary Speciality and Emergency Hospital in Englewood told CBS Denver.
"There are huge spikes in the frequency of marijuana ingestion in places where it's become legal."
Research shows that some dogs are digesting the marijuana because they are eating food in which their owners have put the drug. Cases have quadrupled since marijuana was legalised in Colorado.
Veterinarian Dr Stacy Meol, who coordinated a five-year study that showed the rise, said: "I just want dogs [and] kids to be safe. It needs to be treated like any other drug. If you came home with a prescription of Vicodin from your doctor you wouldn't just leave it sitting there."
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