Colorado veterinarians have a message for medical marijuana users: Don't get your dog stoned. Marijuana is toxic in a dog's system, they say, and has even resulted in some canine deaths.

"There are huge spikes in the frequency of marijuana ingestion in places where it's become legal," veterinarian Dr. Debbie Van Pelt told local CBS affiliate WTSP. "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."

Before medical marijuana was legalized in Colorado, local vets say they saw only a handful of cases of dogs exposed to the substance per year. But now, those numbers have more than quadrupled.

The vets say most of the dogs are getting high from medical marijuana edibles left out in the open by their owners. Marijuana edibles are cookies, brownies and other foods prepared with a butter laced with THC, the psychoactive ingredient in pot.

And while some pet owners may think it's funny to get their dogs high, the vets say pot is actually toxic to a dog's system. Cats are similarly vulnerable to negative effects from inhaling second-hand marijuana smoke or eating edibles. Cat experts say many owners inaccurately believe that marijuana will have a similar effect on their cats as catnip.

"I just want dogs, 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," veterinarian Stacy Meola told the station.

In fact, Dr. Meola said that two dogs recently died after ingesting a lethal amount of marijuana. Such deaths are rare, but even in cases in which a dog's life is not threatened, the dog may still be subjected to painful symptoms, including vomiting and even comas.

"We need people to realize it is potentially toxic and potentially fatal to their pets," Van Pelt said.