Pet owners have been issued a warning after a study found that dogs may be getting high—and sick—from marijuana residue in human feces.
The study, written by two vets from the Australian state of Victoria, looked into historical cases of dogs exhibiting signs of what vets call marijuana toxicosis—negative health effects after exposure to the drug.
Symptoms of marijuana toxicosis include urination, vomiting, lack of balance, a dislike of light and dilated pupils. Serious cases can even lead to death.
Dogs can be exposed to marijuana in a number of ways, such as inhaling smoke, eating cannabis plants or eating products that contain cannabis.
Medicinal cannabis is legal across Australia under federal law, but states have different rules on recreational cannabis. According to the 2019 National Drug Strategy Household Survey, 36 percent of people aged 14 and over in Australia had used cannabis in their lifetime and 11.6 percent had used it in the previous 12 months.
The researchers, whose paper was published in the Australian Veterinary Journal on November 16, studied more than 4,500 records from four animal hospitals in the city of Melbourne. They found 15 cases of dogs who had presented with signs of marijuana toxicosis and a suspicion that they had eaten human feces recently, based on either human observation or vet tests. The records were dated between January 2011 and December 2020.
Of the 15 dogs, eight had to be hospitalized. All 15 were eventually discharged to their owners' care.
According to the researchers, marijuana ingestion by dogs as a result of eating human feces is likely to be "an underreported phenomenon," in part because people are not aware that THC—the psychoactive compound in weed—can pass into feces.
"Awareness of this as a possible source of exposure is important as there are health and safety considerations for the dog, their owners, and veterinary staff," the study said.
The researchers conceded, however, that data was limited because the cases were in the past and it was not possible to follow up on the conditions of the dogs.
According to a 2012 Iranian study, more than 65 percent of cannabis is excreted in feces and around 20 percent is excreted in urine.
The vets' report states that THC may be present in its active form in the feces of a human marijuana user.
This is not the first time that dogs have been reported to be suffering from marijuana toxicity as a result of eating feces.
In 2019, the owner of a pet care center in Colorado said his business saw multiple dogs every week with signs of marijuana toxicity, adding that most owners said they didn't know how their dogs would have come across the drug.
He told The Aspen Times his working theory was that the dogs might have been exposed to the drug in human feces on camping trails.
A study published in September recorded high levels of the drug MDMA in a river close to the site of the Glastonbury music festival in southwest England. The levels, which were high enough to be classed as harmful to aquatic life, were attributed to festival-goers' public urination.