CBD Studies for Dogs: What Does Science Actually Say?


Much has been written and said on how cannabidiol (CBD), the most prominent non-intoxicating compound in marijuana, affects humans. CBD is also available in abundance in the hemp plant. When it comes to animals, especially dogs, the level of research is less detailed, and yet canine owners have no problem giving CBD to their faithful friends.

Due to the lack of scientific research, vets in most states are not allowed to recommend or prescribe any cannabis-based product for your pet regardless of their own opinion. Remember, all state veterinary boards adhere to federal guidelines, and weed is illegal federally. Now that hemp is legal to grow, it will be interesting to see if things change on that front.

Some vets have taken matters into their own hands. According to the California Veterinary Medical Board, nothing in state law allows a vet to recommend, prescribe, or approve a cannabis product for treating an animal. Any vet that incorporates weed into their practices is breaking the law.

However, Dr. Gary Richter, an Oakland-based vet, wasn’t about to give up the fight. In 2017, he created an online petition which was designed to get a ‘compassionate care’ law created for animals in California.

He later confirmed that the bill passed through California State Legislature and was signed into law on September 29, 2018. It has been in effect since January 1, 2019. Richter said that while the bill wasn’t perfect, it was a major step in the right direction and most importantly, the first bill of its kind in the United States.

Richter continued by saying that anything medical weed can do for humans; it is potentially as useful in cats or dogs. While California vets have a little leeway, the same can’t be said in other states. Vets trying to prescribe cannabis to dogs in Alabama could end up in jail for instance.

Overall, the safety and risks of giving CBD to a dog have not been properly researched. Potential side effects, based on what can happen with humans, include:

  • Dry mouth
  • A reduction in blood pressure which causes light-headedness
  • Drowsiness, especially in higher doses

How Much Should I Give My Dog?

Once again, there isn’t enough research to determine the amount that is likely to be therapeutic, and the level that could prove toxic. Studies on marijuana’s toxicity in dogs reveal that as little as a milligram of weed per kilogram could cause cannabis poisoning in canines (although these findings are disputed). However, CBD by itself is unlikely to cause the same issues.

Yet it is important to be cautious when it comes to your pets. We have seen articles online that irresponsibly equate the use of CBD in humans with what happens in dogs. For example, a study by Bergamaschi et al., published in Current Drug Safety in September 2011, found that humans tolerated doses of CBD of up to 1,500mg a day without ill effects. Alas, this means absolutely nothing when it comes to pets until we see clinical studies.

According to Dr. Cornelia Wagner of Hawthorne Veterinary Clinic in Oregon, it is important to start any pet’s treatment with the lowest possible amount. In her opinion, stick to 0.05mg of CBD per kilogram per day. Therefore, if your dog weighs 20kg (44 pounds), don’t give it more than 1mg of CBD in a day.

Make sure you monitor your pet and watch for negative side effects such as excessive excitement or sedation, vomiting or disorientation. If you don’t see any of these effects, it is likely your pet now has a tolerance and you can gradually increase the dosage every five days or so. Keep these increases to 0.05mg per kilogram a day.

Dogs have a more complex endocannabinoid system (ECS) than us with far more receptors. As a result, they feel the effects of THC more strongly than humans; and the same is likely to be the case with CBD.

There Are ‘Some’ Studies Regarding CBD & Dogs: What Do They Say?

Although the phenomenon of CBD stores offering the cannabinoid to pets is relatively new, research into its effects isn’t. The main issue is the lack of clinical studies over the last few decades. Way back in 1988, a study by Mechoulam, Bialer, and Samara, published in the Drug Metabolism and Disposition journal, looked into the pharmacokinetics of CBD in dogs. In case you were wondering, ‘pharmacokinetics’ looks at the movement of drugs within the body.

A group of canines received an oral CBD dose of 180mg and two IV doses of 45 mg and 90 mg respectively. The cannabinoid was quickly distributed after IV administration followed by a lengthy eliminate. Interestingly, the CBD could not be detected in the dogs’ plasma after oral administration in three of the six dogs studied.

In the other three, the maximum bioavailability was just 19%. The conclusion was that CBD is barely absorbed after oral administration; and that the low rate of absorption was probably down to a ‘first pass’ effect.

In what is hopefully the beginning, a clinical study, by Gamble et al., into the effects of hemp-based CBD on dogs with arthritis was published in Frontiers in Veterinary Science in July 2018. In the study, the dogs received one of two treatments, 2mg of CBD per kilogram, or placebo oil every 12 hours. Each treatment lasted 4 weeks with a further ‘washout’ period of 2 weeks.

Aside from displaying no side effects, there was a significant decrease in pain, and an increase in activity, in 80% of the canines that consumed the CBD. The study concluded that 2mg per kilogram of CBD twice a day could help dogs with osteoarthritis. It is interesting that the dose is far higher than what is recommended by Dr. Wagner.

Ongoing Clinical Studies on CBD in Dogs

Dr. Stephanie McGrath works at Colorado State University and has completed a pair of clinical studies on the effects of CBD in dogs with epilepsy or osteoarthritis since 2016. McGrath, who is located at the College of Veterinary Medicine & Biomedical Sciences at CSU, had no interest in marijuana as a therapeutic drug until 2012.

In that year, cannabis became legal recreationally in Colorado, and she received a lot of calls from people asking if CSU was conducting any research into the herb’s medical effects. Eventually, she began studying the effects of cannabidiol on dogs with epilepsy and OA using CBD provided by the Applied Basic Science Corporation.

In her initial study, McGrath looked at 30 healthy animals and found that they tolerated CBD in certain amounts. While the studies have been completed, the research team are still looking at the data. The results from the preliminary epilepsy study were so promising that the American Kennel Club provided $350,000 worth of funding to allow McGrath to begin a three-year crossover study into how cannabidiol affects dogs with the condition.

Final Thoughts on CBD & Dogs

We have heard some remarkable studies about how CBD has changed the lives of pets for the better. For example, an old Staffordshire terrier had a 6cm mammary tumor and metastasis. Within three months of using CBD, the tumor vanished and has not returned since. In another case, a Jack Russell Terrier had agonizing arthritis and a serious heart murmur. Within a month of using CBD, the murmur improved and the dog was keen to go for walks.

The list of potential benefits for CBD in humans is long and includes:

  • Preventing the growth of cancerous tumors.
  • Reducing anxiety disorders, depression, and PTSD.
  • Reducing the seizures suffered by those with epilepsy.
  • Relieving chronic pain.
  • Reducing chronic inflammation.
  • Preventing Inflammatory Bowel Disease.
  • Reducing the impact of neurodegenerative diseases and protecting the nervous system.
  • Reducing nausea and improving appetite.
  • Reducing the harm caused by damaged blood vessels, and reducing heart rate & blood pressure.

The trouble is, all of the apparent benefits listed above were seen in studies on humans, and they are disputed by medical experts who claim there isn’t enough evidence to draw such conclusions. When it comes to pets, there is even less evidence of how CBD can have a benefit.

It is true that preliminary research is promising, and it may be worth giving your dog a tiny amount of CBD if it has a condition such as epilepsy or osteoarthritis. However, we would urge caution and recommend stopping CBD treatment if your pet shows any negative side effects. Hopefully, ongoing research will shed more light on the puzzle but until then, don’t take chances with your pet’s health!