After the 2018 Farm Bill removed most hemp products from the Controlled Substances Act, cannabis-based consumables proliferated for dogs, cats and other pets. While hemp seed oil, hearts and protein powder are Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration, cannabidiol (CBD) remains in regulatory limbo. Likewise, despite the proliferation of CBD products appearing in the pet supplement space, the actual effects of the chemical on dogs and cats haven’t been thoroughly evaluated under controlled conditions.
To help meet this need for empirical information about CBD in pet supplements, researchers with Colorado State University and Hill’s Pet Nutrition collaborated in a long-term study of CBD’s effects on dogs. After 36 weeks of CBD supplementation, none of the dogs in the study showed serious health problems. Only at the highest dosage did some of the dogs get loose stools.
“This study was important to show that dogs are able to tolerate doses generally much higher than what most of these brands are marketing towards,” Breonna Kusick, neurology clinical trials manager at Colorado State University told pet food industry. “However, it's important to note that these are all very healthy dogs, and the higher doses may not necessarily be as well-tolerated in dogs with any sort of illnesses or on any additional medications. With that said, I think it's important for CBD-based pet supplement brands to continue reviewing new literature to stay on top of their own recommendations. I also think it's helpful for these brands to understand what to watch for (such as signs of liver disease) for pet parent education.”
Dog owners who choose to supplement their pet’s diets with CBD should watch for signs of liver disease, including vomiting, diarrhea, decreased appetite and general fatigue, Kusick said. Yellowing of the eyes and skin can be signs of more advanced liver disease.
“Any pet on CBD experiencing any of those signs should be seen by their veterinarian as soon as possible for bloodwork and possibly more advanced diagnostics,” she said.
In the study, the researchers assigned 18 healthy adult Beagles to three groups of
six. Each of those groups received 0, 5 or 10 milligrams of CBD per kilogram of body weight every day for 36 weeks.
“This study shows that while the doses are well-tolerated, there is a reported adverse event of softer stools and one liver enzyme is consistently elevated, although not enough to be significant,” Kusick said. “However, that's only on the highest dose of 10mg/kg/day. So, as the paper mentions, that dose should be used with caution, and it probably wouldn't be helpful in an otherwise healthy dog. In terms of the 5mg/kg/day dose, it's difficult to make any sort of conclusion about a positive or negative influence on pet health since no significant adverse events were seen and the dogs' overall health was the same at the end of the study as it was at the beginning.”
The study wasn’t designed to examine the positive effects of supplements on dogs' health or behavior. Likewise, the dogs were all healthy to begin with, so there were no disease symptoms to be remedied.
“There's still a high need for more studies to be conducted looking at CBD's effect on different disease processes,” Kusick said.
CBD regulation in pet products
While this and other studies haven’t found low doses of CBD to be harmful to dogs, cannabidiol remains restricted to pet supplements, as does the hemp CBD comes from. Interest in the use of hemp in commercial animal feed has accelerated since the passage of the 2018 Agricultural Improvement Act (“Farm Bill”). While the Farm Bill expanded the legal production of hemp in the United States, the use of hemp and hemp by-products in animal feed, including pet food, remains under the jurisdiction of the U.S. Food and Drug Administration (FDA) and state regulatory programs for commercial animal feed.
This year, as negotiations for the next U.S. Farm Bill commenced, a coalition of 33 hemp industry groups called for the regulation of CBD and other ingredients derived from hemp under the existing frameworks for dietary supplements and food additives as outlined in HR 1629 and S 2451.
“There's still a bit of a ‘wild west’ component to CBD as the market is not regulated so it's important to always look for a certificate of analysis when considering any CBD-based products,” Kusick said.