Oils containing CBD in a shop in a store. Some pet owners swear by the cannabis compound, but little research has been done on its use in animals. (Geoffroy Van Der Hasselt/AFP/Getty Images)

Consumer Reports has no financial relationship with any advertisers on this site.

Ella, a 10-year-old St. Bernard, doesn’t like loud noises. At the first rumble of thunder or pop of fireworks, the dog starts panting and pacing, says Jeffrey Powers, Ella’s owner and a veterinarian who practices in northern Michigan. “The minute fireworks go off, she’s running to hide,” he says.

At least, that’s what used to happen. But recently, Powers says, he has found a way to control his dog’s noise anxiety: cannabidiol — a.k.a. CBD, a compound that can be extracted from cannabis, which includes marijuana and hemp.

CBD is thought to have many therapeutic properties, but unlike cannabis’s other main compound THC (tetrahydrocannabinol), it doesn’t get users high. And Powers, who is also vice chairman of the American Veterinary Medical Association’s Council on Biologic and Therapeutic Agents, credits CBD for easing his dog’s distress.

But Powers is not legally allowed to prescribe or even recommend CBD to his veterinary clients because, on the federal level, CBD remains categorized by the Drug Enforcement Administration as a Schedule 1 controlled substance, the same as heroin.

As of July 2018, 47 states have gotten around this federal restriction by legalizing CBD for human use within their own states, according to the National Organization for the Reform of Marijuana Laws. Physicians there can now recommend CBD to their patients, and consumers can often buy the compound on their own — for themselves or their pets — without any interaction with a health-care professional.

If, however, you want guidance from a veterinarian about CBD for your pet, you’ll have to start the conversation. That’s because vets have been left out of most state laws concerning cannabis, so they can talk about CBD only if clients broach the topic.

Despite this lack of official guidance, pet owners are increasingly seeking out CBD for their furry family members. In a survey conducted this year by the Veterinary Information Network, an online community of veterinarians, nearly two-thirds of survey respondents said they were asked about cannabis by their patients at least once a month.

Fueled mainly by anecdotal reports, people are turning to CBD to help manage pain, arthritis, seizures and other health problems in their pets. And a growing crop of CBD products marketed for pets — including tinctures, capsules and chew treats — has burst onto the market to meet the consumer demand.

But, as Powers acknowledges, there’s even less research for those uses in animals than there is for humans. And while studies suggest CBD doesn’t pose a risk of addiction and generally causes few side effects, there are some risks, says Casara Andre, founder of Veterinary Cannabis Education & Consulting, a resource for pet owners and veterinarians.

If you’re considering CBD for a four-legged member of your household, check out what the experts have to say first.

Have realistic expectations

Some pet owners swear by CBD, but researchers are just starting to learn how to use it for pets, says Stephanie McGrath, a veterinarian and assistant professor of neurology at Colorado State University’s College of Veterinary Medicine and Biomedical ­Sciences.

In 2016, she conducted some of the first studies looking into basic questions about how CBD is metabolized by dogs and whether the compound poses any immediate health threats. After her initial research, McGrath began two clinical trials, one on dogs with epilepsy and another on dogs with osteoarthritis. Early results are encouraging, she says, but she notes that the results are not yet final or published.

A separate study from Cornell found that 2 milligrams per kilogram of CBD twice daily “can help increase comfort and activity” in dogs with osteoarthritis.

McGrath, however, is still cautious about touting CBD’s promise until larger studies are done.

“I feel really comfortable at this point, given all of our clinical trials and our initial research, that it’s a safe product,” she says. “But the jury’s still out on whether I’m totally convinced about its effectiveness.”

Talk with your vet

If you live in a state that has legalized CBD, there’s nothing to stop you from giving it to your pet on your own. But experts say it’s a good idea to talk with your vet first. And while veterinarians can’t bring it up themselves, they can certainly answer questions you have in an effort to reduce any potential harm to your pet, Andre says.

If your vet doesn’t know much about CBD, consider going to Veterinarycannabis.org for help.

Choose products carefully

Because cannabis, especially for pets, is largely unregulated, it can be difficult to know which CBD products have been formulated responsibly, are free from contaminants and contain the ingredients that the product labels list.

So when shopping, look for products that claim to follow Good Manufacturing Practices or that have a seal from the National Animal Supplement Council (NASC). These labels increase the chance that a product has been made with safe ingredients in a clean, high-quality environment, says Stephen Cital, a veterinary technician, cannabis consultant and co-founder of the Veterinary Cannabis Academy.

Wondering whether you should give your pet a CBD product meant for humans? “Some human products have other things in them, such as xylitol or grapeseed oil, that could be toxic to the animals,” Cital says.

Be particularly cautious about products that also contain THC. While some veterinarians use it to treat certain conditions in animals, experts don’t recommend that pet owners experiment with THC on their own.

For any CBD product for you or your pet, your best bet is to find a company that has commissioned independent third-party testing and can provide a Certificate of Analysis, or COA.

The lab results should show how much CBD (and THC) the product contains, as well as how the product did in tests checking for contaminants such as heavy metals and fungicides, Cital says. If you can’t find a COA on the company’s website or the company refuses to share it, that’s a red flag.

Watch for interactions

Though CBD seems to cause few side effects, Andre points out that cannabis does interact with some drugs. So it’s important that you and your veterinarian be alert to any changes in your pet.

“We do see the strength of pharmaceuticals increase when dogs are taking CBD, so we can often taper down some of those pharmaceuticals,” Andre says.

Dose gradually

Although some CBD products have dosing instructions on the label, little is known about what doses are most effective and safe.

For example, while McGrath’s initial research in dogs used 2.5 mg per kilogram twice a day, she is now using nearly double that dose in her latest trial. And Judy Morgan, a holistic vet in New Jersey and co-author of “Yin & Yang Nutrition for Dogs,” recommends starting with 1 mg per 10 pounds of body weight twice a day — and monitoring your pet’s reaction.

Until more is known, the experts urge caution. “Numbers are really useful, but cannabis is a very individualized medicine,” Andre says. She advises that pet owners “start low and go slow” when figuring out a dosage. She also suggests that using tinctures rather than a chew treat can make it easier to scale dosages up or down.

Store products carefully

“Cannabinoids are susceptible to degradation. Oils and treats should be kept at room temperature away from bright lights or sunlight,” Cital says. “Heating and extreme cold can dramatically change chemical composition.”

If you have an oil that has changed colors, it’s probably damaged and should be discarded.

 Copyright 2018, Consumer Reports Inc.

Consumer Reports is an independent, nonprofit organization that works side by side with consumers to create a fairer, safer, and healthier world. CR does not endorse products or services, and does not accept advertising. Read more at ConsumerReports.org.