What Are The Side Effects Of CBD Oil For Dogs?

Filed in Dog Health by on November 21, 2021

What Are The Side Effects Of CBD Oil For Dogs

Relief from pain, anxiety, seizures, even cancer – CBD oil for dogs is becoming known as a natural cure-all.

It’s certainly a hot topic and a hot commodity, with many people interested in learning more about how it can help their four-legged friends!

However, with its potential benefits, you may be wondering what are the side effects of CBD oil for dogs?

Short answer: Some possible side effects include dry mouth, blood pressure drop, drowsiness, diarrhea, vomiting, changes in liver enzyme values, and medication interactions.

As of now, there are limited studies and no guidelines from the FDA on CBD for dogs or its safe usage. It’s advised to start with low doses then monitor your dog’s reaction.

Possible Side Effects of CBD Oil for Dogs

Dog Endorsed previously has covered the potential benefits of CBD oil for dogs. And there are lots of personal and encouraging stories out there covering how it can help our beloved furry family members.

I tried it on my dog Pippin when he developed arthritis. It helped.

But there are possible side effects you need to know about. Here’s a look at what we discovered about them so you can balance the information and decide if you want to give this new kid on the block a go…

• Dry Mouth – The AKC’s Chief Veterinary Officer, Dr. Jerry Klein, says there’s no scientific data on the side effects of CBD oil for dogs but says there are potential side effects based on how CBD affects humans. He says: “Research has shown that CBD can decrease the production of saliva. For dogs, this would mean increased thirst.”

• Blood Pressure Drop – Dr. Klein also says that high doses of CBD have been known to cause a temporary drop in blood pressure resulting in light-headedness.
drowsy dogs lying on the sofa

• Drowsiness – Dr. Klein adds that when used to treat anxiety, the calming effect of the oil can cause drowsiness. If this happens, the dosage might be too high, and you would reduce it.

• Diarrhea – Upset stomachs can occur when you give your dog something new to eat or a new supplement. The carrier oil for the CBD can also be the culprit.

• Vomiting – An upset stomach can also cause vomiting. The bitter taste of the oil can also cause your dog to vomit.

• Changes in Liver Enzyme Values – In some studies, there was found to be an increase in a specific liver enzyme called SAP, although no real-world effects were seen from it. I further discuss these studies in “The Studies” section of this blog post.

• Medication Interactions – If you don’t tell your vet you’re giving your dog CBD oil and your pet is on a drug, there could be harmful interactions between the two.

The American Kennel Club (AKC) says: “The worst CBD has been documented to do is cause diarrhea and changes in some liver enzyme values. The main concern with CBD is that it inhibits a chemical in the body responsible for metabolizing most drugs. CBD could render it less effective. If a drug’s safety depends on it being cleared from the body within a certain time frame, CBD could cause it to build up to toxic levels.”

Things That Must Also Be Considered

In addition to the side effects of CBD oil for dogs, there’s also other things that must be considered related to its safety. What are they?

• Sourcing – There are good and bad sources of CBD oil. If you buy it from your local gas station, do you know what’s in it? The company selling you the product should show proof on their website of third-party testing to prove that what they say is in their product is in there.

The documentation should also verify that the product is free of toxic contaminants such as heavy metals and pesticides (always buy organic). The product needs to be THC-free or contain only trace elements.

• Dosage – There are no federal regulations yet, and overdosing is possible. Dr. Gary Richter says: “Depending on how significantly a pet is overdosed, the effects of that can be quite long-lasting.” But he does say that life-threatening risks are rare.

Dr. Casara Andre, DVM adds: “Our clients are out here lost at sea. And we’re seeing a lot of reports of intoxications.” Previously, Dog Endorsed discussed the recommended CBD dosage for dogs from various sources.

• Ignorance – If you try to administer CBD oil to your dog made for humans, you may run into a world of hurt. Some contain xylitol, an alternative sweetener that’s safe for humans but potentially lethal for pets. Some oil for humans contains THC, and this is a no-no for pets.

• Scams – Some products that say they contain CBD oil don’t do so. “You’d be astounded by the analysis we’ve seen of products on the shelf with virtually no CBD in them,” said Cornell University veterinary researcher Joseph Wakshlag.

How Did CBD Oil For Dogs Get On The Market?

CBD oil in a small glass bottle

Anything connected to marijuana, hemp, CBD oil, etc. is controversial. There’s a lot of misunderstanding. We’ve seen how there can be side effects for dogs, so how did this all start?

Changes in federal law in 2018 legalized hemp-based products in the U.S. so long as they contained less than 0.3% THC, the psychoactive ingredient that produces the high in marijuana.

Since then, their popularity has skyrocketed for humans and pets as the market for them boomed.

When I tried it out I had no idea if there would be any side effects – I was on my own. My vet couldn’t recommend it or know what to do if anything went wrong.

More research, studies, and trials are needed, and until then the FDA is discouraging hemp use in pets.

Most veterinarians are left high and dry. They can see how it might help pets, but they haven’t been given any guidelines yet. And except for those licensed in California, Colorado, and Oregon, by law, vets can’t even discuss CBD products with pet moms and dads.

A Vet’s Word Of Caution

Catherine Ashe, DVM, interviewed by The Whole Dog Journal, is very blunt. She says: “If you decide to administer products that contain CBD to your dog, you need to be aware that they are untested and unapproved. Your veterinarian may not have any experience or reliable information about any adverse reactions your dog experiences.”

Vets also know that very few studies are out there that directly examine CBD oil’s side effects on dogs.

Dr. Ashe says: “Other than a handful of small-scale studies looking at the use of CBD oil in dogs, there is no data on veterinary usage. Most available information is individual case studies or anecdotal.”

The Studies

researcher examining medicinal cannabis

So, where does that leave pet doggie parents who would like to try this natural treatment? Can those small studies shed any light on the matter?

Not a whole lot, it seems. This is what Dr. Ashe found:

  1. In 2018, researchers at Cornell University published a study in Frontiers in Veterinary Science on the effects of CBD oil on dogs with osteoarthritis. The study concluded that hemp-based CBD appears to be relatively safe for healthy dogs and made a significant reduction in pain.

The only side effect was an increase in a specific liver enzyme called SAP. The same issue also occurs with drugs that use the liver. Why this happens is still unknown.

Dr. Gary Richter of the Montclair Veterinary Hospital in Oakland, California, says: “The elevation does not appear to cause any real-world issue, in the sense that it doesn’t make the dog sick. And it is reversible if you stop giving the CBD.”

  1. Later in 2018, Dr. Ashe says a further study using healthy dogs noted that they all developed diarrhea – and some also had an increase in the SAP enzyme.
  1. Finally, she found an epilepsy study in 2019 by the James L. Voss Veterinary Teaching Hospital at Colorado State University. Researchers used CBD oil in combination with traditional anti-seizure medication.

Some dogs got the mixture, and some a placebo. The dogs with the real thing showed an encouraging decrease in seizure frequency. But SAP levels also increased.

Since the time that Dr. Ashe looked for studies, another was published in the Pain journal in September 2020. It was a small research program performed by researchers from Baylor College of Medicine.

It also looked at dogs with osteoarthritis. They used different strengths of CBD oil and a placebo.

They report that the dogs who took higher doses of CBD saw “significant improvement in their mobility and quality of life.” No negative side effects were stated.

Dr. Ashe says all the results need further study. But she’s encouraged: “The American Veterinary Medical Association is actively encouraging well-controlled studies into the uses of cannabinoids at this time. It is also working with the FDA to encourage the development of veterinary-specific products. State veterinary associates are making strides, as well, in addressing the sudden abundance of products and claims.”

Bridging The Gap

holding medicinal cannabis and ampoules

Obviously, there’s a big gap in the scientific study of how CBD oil can help our pets.

But things are improving. As the popularity of CBD oil for both humans and pets increases, so does the number of vets and scientists examining it.

We now have a Veterinary Cannabis Education and Consulting team. Founder Casara Andre, DVM, is attempting to fill the cannabis information gap with a veterinary cannabis counselor certification for practitioners worldwide.

She says: “Pet parents can come ask their questions, talk to us about their goals, maybe tell us what products they are using or want to try, then we can give both the pet parent and the veterinarian some guidance.”


People are buying CBD oil for themselves and their pets worldwide, and there’s no safety net.

Few vets can offer guidance, and yet the guy in the local health store can. That leaves us with having to research this supplement ourselves and weigh the good with the bad.

The biggest problem is that the safety of using CBD for dogs still needs more research. The AKC says: “The FDA has not approved CBD and has not issued a dosing chart. Therefore, we do not know what size dosage would be toxic. Any medication or supplement carries the risk of a reaction. It’s always advisable, when giving your dog something new, to start with small amounts and then closely monitor the effects.”

The good news is that side effects of CBD oil for dogs seem to often be mild. With time and further study, it will get less and less like the Wild West in the world of CBD oil for dogs.

In the meantime, be aware of possible side effects and things that can go wrong and use your best judgment if you would like to try it on your dog.













About the Author

Wendy Hollandsworth is a contributing writer to Dog Endorsed. She is a freelance canine copywriter who specializes in blog posts, content articles, product descriptions, and sales emails. An experienced editor and writer, she’s worked in four countries, has had hands-on experience with dogs in boarding, grooming, training, and pet-sitting, and loves what she does. When she’s not creating content she’s usually taking her three dogs Finn, Meg, and Ziggy Stardust to the dog park or making them a home-cooked meal! Sometimes her husband gets one, too.

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