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Cannabidiol (CBD) for Dogs - Safety & Things to Consider

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Before digging deeper into this article, please be sure check out our article on CBD for Dogs: The Basics to learn more about CBD and THC, and the health benefits of giving CBD to your dogs.

Is CBD safe for dogs? 

The short answer: yes!

CBD is safe for dogs in reasonable doses. But, like with conventional medications, there are potential side effects and concerns about contamination, which we’ll explain.

Side Effects 

While clinical research is still very limited on how CBD impacts dogs, early studies looked into how drugs are processed by the body (known as pharmacokinetics), tolerance, and safety of CBD in dogs.

In one study, four male Beagles were provided 2 and 8 mg/kg CBD oil, revealing an elimination half life (the time required for the amount of drug in the body to decrease by half) of 4.2 hrs and no apparent side effects. One thing that was noted is increased serum alkaline phosphatase (ALP),1 which is a common enzyme measured in bloodwork. While elevations of this enzyme may not cause any issues in a dog itself, it could indicate the potential for interactions with other drugs that are metabolized by the liver. 

Further pharmacokinetic studies have revealed that CBD is fat soluble, and readily absorbed into tissues. However, it is subject to the “first pass effect,” which means that when taken orally, the concentration is significantly reduced before entering circulation, especially when not given with food.2 In 30 dogs who were provided with 75 and 150 mg CBD as oral capsules, oral oil, and transdermal cream, it was found that absorption was higher at higher doses and most favorable with the form of oral CBD oil.3

Another study examining the tolerability of 10 and 20 mg/kg body weight per day of CBD capsules, oil, and transdermal cream for 6 weeks noted increased serum ALP levels as a possible adverse effect, which could indicate liver problems, and warrants more research.4 Additionally, all dogs in this study developed diarrhea, so further research is required to determine if an association with CBD use exists.4

It’s important to note that to examine tolerability, these pharmacokinetic studies used CBD doses higher than is expected to be used clinically (≤5 mg/kg body weight daily), and found that even at high doses (≥10 mg/kg body weight daily) CBD side effects were minimal.4,5

When dog owners were asked about observed side effects of canine cannabis products, they commonly noted sedation, increased appetite, and dry mouth. Less frequently, they noted lack of energy, vomiting, and panic.6,7 US veterinarians with experience using canine CBD products noted sedation, vomiting, increased appetite, anxiety, diarrhea, decreased heart rate, and anorexia as some of the more commonly seen side effects.8 

The takeaway: overall, especially compared to some of the side effects of some conventional medications for similar conditions, CBD at reasonable doses (≤5 mg/kg body weight daily) appears to be clinically well tolerated by dogs.

Unregulated Industry = Contamination Concerns

CBD isn’t necessarily the concern when it comes to cannabis products for dogs. It’s THC, which, while used both recreationally and medicinally by humans, is toxic to dogs at certain doses.More information on the the difference between CBD and THC here.

This difference in tolerability is thought to be due to the increased number of cannabinoid receptors present in the canine brain, creating a heightened sensitivity.2 Fatality from ingestion of THC is rare, but common signs of THC poisoning in dogs include vomiting, delirium, increased sensitivity to touch and light, decreased heart rate, increased saliva, and overall lethargy.2 

So if THC is toxic to dogs, and CBD is beneficial, the solution appears clear: avoid giving them THC. Right? Unfortunately, the veterinary CBD industry is currently unregulated, which means it’s not so simple. Legally, in the US, hemp (and thus hemp-derived CBD) must contain no more than 0.3% THC.9 However, one study found that several CBD products, including oils, creams, and capsules all contained less CBD than advertised, and found contamination of THC.4 

Another study analyzing 75 cannabis products found only 17% to to have accurate product labels.10,11 And a study looking at the composition of 13 commercially available hemp CBD oils found the majority had lower CBD levels than advertised, and many were contaminated with THC.12

Together these studies have revealed the label inaccuracy and variety in nomenclature that exists on current veterinary CBD products. Further, FDA product testing of CBD products revealed some products didn’t even contain CBD at all.13

The lack of regulation of products brings concerns not only about THC contamination, but further contamination concerns around synthetic cannabinoids, sourcing, and processing practices.2,14 Synthetic cannabinoids, while mainly banned under the 2011 Synthetic Drug Control Act, could still contaminate pet products — and they’ve been found to be even more toxic to dogs than THC.2,7 Solvent-based extraction of CBD can leave chemical contaminants which can pose health concerns.2 Legality concerns also mean many companies source cannabis from abroad, which could lead to contamination with heavy metals and pesticides.13 So while CBD itself is proving beneficial for dogs, poor-quality CBD products are complicating safety. 

The growing acceptance and legal status of cannabis products in the US also means more opportunities for pets to be exposed to it. Exposure of dogs to THC has risen not just due to poor-quality pet products but also because dogs may get into their owners’ THC-containing products. Edibles left out look just like a tasty treat to dogs! And human products, especially gummies, are additionally often sweetened with xylitol which is toxic to dogs.15 Unfortunately, calls to the Pet Poison Helpline have skyrocketed in recent years, with calls reporting marijuana consumption increasing by 448% between 2011 and 2017.6

We’ll go into full legal details later, but complicated legal status hampers research, and veterinarians often feel unsure if they can discuss and recommend CBD. The FDA recently ruled CBD as not Generally Recognized as Safe (GRAS) for pet food use, due to liver concerns, possible drug interactions, contamination, and concerns of side effects including mood changes, sedation, and diarrhea.14

This ruling has caused concern among pet owners, further challenging manufacturers’ ability to produce quality products, and continuing to silent veterinarians. Veterinarians should be the primary source of information for consumers, but unfortunately they often rely on CBD company websites, which can be unreliable and pose further safety concerns.6 With the lack of regulation and research, it is often in the vet’s best interest to express caution to pet owners interested in CBD products unless the vet has specific knowledge of individual products that are safe and effective.16

What is full spectrum CBD oil vs CBD Isolate? 

When you purchase CBD oil for your dog, you may come across the terms “full spectrum” or “isolate.” What’s the difference? 

The main difference is that “full spectrum CBD” includes other cannabinoids and terpenes naturally present in the cannabis plant. However, this means that trace amounts of THC (< 0.3%) may be present, and while this low level is generally argued to be not an issue for dogs, it can cause hesitancy by some vets.17

“CBD isolate” is, as the name implies, isolated and pure CBD, with no additional cannabinoids, no terpenes, no THC, nothing but CBD.18 So if CBD isolate is pure it must be better, right? Not necessarily. 

While CBD isolate does have the benefit of being used in more clinical studies, and is therefore more “trusted,” it misses out on what is known as the “entourage effect”.19 The “entourage effect” is the concept that cannabinoids and terpenes (another class of compounds in cannabis) have a synergistic effect on one another, and are thus more effective together.1,18 This means that full spectrum CBD oil can potentially be more effective than CBD isolate. 

Common additional cannabinoids found in full spectrum CBD oil include: cannabidivarin (CBDV), cannabichromene (CBC), cannabigerol (CBG), and tetrahydrocannabivarin (THCV), all of which have suspected supplemental neuromodulating properties.13,17 Additionally, terpenes have many known therapeutic benefits, provide cannabis plants with distinct aromas and flavors, and are found in a wide variety of plants and spices. Common terpenes present in full spectrum CBD oil include: beta-caryophyllene, limonene, myrcene, linalool, and humulene.18 Additional cannabinoid and terpene content will vary among different products, as they vary in different plants, and you’ll have to contact the manufacturer (if not on the label) for full product analysis.

You may also come across CBD oil termed “broad spectrum.” This is essentially a cross between full spectrum and isolate, where CBD is isolated and selectively combined with specific cannabinoids and terpenes. This allows for THC to be removed entirely, the “entourage effect” to be present, and specialized formulas to be made.20 

The debate on which form to provide to dogs is ongoing in the veterinarian community. Some are advocates of the “entourage effect” while others appreciate the clinical evidence behind CBD isolate.17 While studies in mice have demonstrated additional health benefits with the use of full spectrum CBD compared to isolate,21 these studies do not yet exist for dogs.  However, full spectrum products have been used in recent and on-going canine clinical trials for epilepsy,22 arthritis,1,23 and cancer.24 Emerging evidence is demonstrating the therapeutic benefits of full spectrum CBD products on canine health problems, but direct comparisons between full spectrum and isolate on health outcomes for dogs have yet to be made. 

Advantages

Disadvantages

Full Spectrum CBD

  • “Entourage Effect”
  • Includes all cannabinoids present in plant while THC < 0.3%
  • Includes terpenes
  • Most natural 
  • Readily absorbed
  • May include trace levels THC
  • Distinct color and smell
  • More side effects possible

CBD Isolate   

                              

  • Pure CBD
  • No THC risk
  • Trusted therapeutic form
  • Odorless
  • No “Entourage Effect”
  • Removes all other cannabinoids and terpenes
  • Powder in pure form, not as readily absorbed
  • Many companies sell in oil

 

How do I ensure a quality CBD product? 

Since this is an unregulated industry, and the FDA is not doing much policing, customers are left to do their own due diligence.25 Hemp products for pets are not regulated as food or drugs, so they are most commonly treated like supplements, which means a lack of testing.16

So, when looking to buy a canine CBD product: a) don’t price shop and b) keep an eye out for these things: 

                What dosage should I give?

                While proper dose is crucial to ensure benefits, dog owners can rest easy knowing even at very high doses of CBD (i.e. 20 mg/kg body weight per day) there have been minimal adverse effects reported and that, overall, CBD is considered relatively low-risk.4,5 However, do note that higher doses can still lead to some unwanted side effects, so it is best to follow dosing guidelines. Overall, the appropriate dose to give your dog will depend on their size, the product you’re using, and the condition being treated.

                Every dog is different, and dose adjustments may have to be made over time. As a rule of thumb start small to avoid negative side effects, and increase as seen fit to maximize benefits. 

                Anecdotal reports have suggested benefits with doses between 0.5 - 2 mg/kg body weight per day.1 However, based on scientific reports, benefits have been seen with starting doses between 2 - 5 mg/kg body weight per day, which for a 15 kg dog (~35 lbs) would be between 30 - 75 mg CBD per day.4,36 Weight and size are generally the basis of dosing guidelines,32 but monitoring your pet and adjusting dose as necessary is ideal. Starting out with a smaller dose not only helps prevent side effects, but also avoids unnecessary product use.4 

                Generally, effects can be seen within 30-60 minutes and last about 6-8 hours.33,36 Pharmacokinetic studies have displayed a relatively rapid elimination of CBD, suggesting a dosing schedule of 2-3 times per day.1,37 While very higher doses, such as 20 mg/kg body weight per day, have been shown to be relatively well tolerated, it is recommended to use the lowest effective dose, as side effects, including liver problems, are still being researched.4

                Product websites should also provide additional dosing information calibrated to the strength of their product. Many manufacturers make products of varying potency, ideal for different sized dogs, and often adjust their dosing guidelines for oils to the number of “drops” required. For example, one company sells 125 mg CBD bottles (0.13 mg CBD per drop), 250mg CBD bottles (0.25 mg CBD per drop), 750 mg CBD bottles (0.76 mg per drop), and 1500 mg CBD bottles (0.76 mg CBD per drop). Dosing guidelines are subsequently adjusted based on potency and explained by the number of drops to give, every 6-8 hours, based on your dog’s size and the condition you wish to treat.

                How can I administer CBD to my dog? 

                There are a variety of pet CBD products available. The main differences involve absorption rate, ease of administration, and available doses. See the table below for more detailed descriptions of available products.

                Form of CBD

                Product Description

                Oil/Tinctures

                Either available as full spectrum or CBD isolate. An oil tincture indicates the presence of other compounds (i.e. terpenes). Found to have best absorption and fastest (10-30 min).3,36 Allows for easy adjustments of dose.27 Administered orally and absorbed directly into the bloodstream. Some dogs resist dosing and dislike flavor.5

                Capsules

                Encapsulated oil or powder, administered orally. Oil is more readily absorbed, as CBD is lipophilic (fat soluble).38 Takes a bit longer (30-60 min) than pure oil to be absorbed and see effects.36 Can select desired dose from a variety of available options. Can be hidden in treats for ease of consumption.5

                Topical Creams

                Not a typical form of administration, but when used frequently applied to ears or bare skin (no fur or can’t lick easily).5,10 Often used for pain relief from rashes, joint stiffness, and muscle aches but with unknown effectiveness,5 and can sometimes cause a skin reaction.4

                Edible Treats

                Made with a generic, well-tolerated dose. The dose is unlikely to be therapeutic for medical conditions. Must be digested before effects are seen (30-60 min).36 Easy, fun, and tasty way to give your dog CBD with a variety of dose options, flavors, and treat forms available.5

                 

                Where can I buy them?

                A 2018 survey of dog owners’ use and perception of cannabis products revealed that the most common places owners purchased cannabis products for their dog were online (72.9%), pet stores (21.95%), human dispensaries (15.7%), from friends/family (10.1%), and from their veterinarian (9.6%).7 The most common forms of CBD products purchased are pet specific capsules (56.9%), pet specific treats (29.3%), human topicals (8.5%), pet specific topicals (7%), human capsules (3.9%), and human edibles (2.6%)(This survey did not include liquid oils/tinctures).

                Availability of pet CBD products from different sources, including online and at dispensaries, differs between states.2,39 Access to quality products can be an issue for some owners seeking to provide CBD to their dog.

                Who is buying them?

                The same survey revealed common characteristics among those purchasing canine CBD products. Gender and legal status were not associated with the purchasing of canine cannabis products, however, age and education status were. Those buying CBD for their dogs were found to be older and more educated.7

                Other Considerations

                If you feel CBD is something you’d like to try for your dog, consider addressing it with your veterinarian, especially if your dog is taking any medications, as CBD can interact with certain medications, or reduce the liver's ability to metabolize them and hamper their effectiveness.5 Be thorough in your search for an appropriate product and demand quality. If you see the positive or negative impact CBD makes for your dog, join the discussion, help be a resource for other dog owners, and encourage your veterinarian to be part of the journey with you.

                Please be sure to also check out our content on CBD for Dogs: Legality to learn more about the laws and legal terms surrounding CBD products in the US.

                 

                References:

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                2. Brutlag A, Hommerding H. Toxicology of Marijuana, Synthetic Cannabinoids, and Cannabidiol in Dogs and Cats. Vet Clin North Am Small Anim Pract. 2018;48: 1087–1102.
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