Walter the Staffordshire bull terrier loves to go for walks around his Studio City neighborhood and, like most dogs, he'll go where his nose leads him.
But something unusual and alarming happened after Walter checked out a discarded item under a bush. His reaction would make any dog owner's heart skip a beat.
"All of a sudden he got something to eat from under the bush that I didn’t see," said owner Steve Hofstetter. "The next morning, he was a different dog. He was stumbling a lot. He was bumping into things."
Hofstetter brought Walter to a veterinarian whose first question was whether Walter had ingested THC, an ingredient found in marijuana. Walter's tests showed he had THC poisoning.
"I never thought about it before. I don't smoke," Hostetter said. "And, I was thinking, 'Well, how the hell is that possible?'"
It turns out pet marijuana poisoning reports have increased since recreational marijuana use became legal in California. The NBC4 I-Team looked at data from the American Society for the Prevention of Cruelty to Animals poison control center that shows there were 132 marijuana-related calls to the agency in 2015.
So far in 2018, that figure has jumped to more than 186. Most cases go unreported, according to the ASPCA.
"We're seeing at least a case a week, usually," said Julio Lopez, a veterinarian at Santa Monica Pet Medical Center. "There are some times during the weekends where we may even see two or three pets within the same day."
Many dog owners might not be familiar with the symptoms. Jolene the French bulldog, for example, was fine one day, but take a look at what happened after she accidentally ate marijuana she found on a downtown Los Angeles sidewalk.
Common symptoms include difficulty standing, wobbly legs, bladder control problems, vomiting and hyper-sensitivity.
Then there are more severe reactions, like Walter's. He's still having regular seizures. Marijuana ingestion is not fatal for most dogs, but they usually require supportive care for 12 to 24 hours.
It's a problem that can easily be prevented.
"I'm very pro-legalization," Hofstetter said. "I just think people need to be careful with it."
NBC4's Jonathan Lloyd contributed to this report.