By Katy Miller, DVM; Mary Cope, PhD; Bradley Quest, DVM; Stephanie Clark, PhD; and Michael Johnson//May 8, 2023//
By: Katy Miller, DVM; Mary Cope, PhD; Bradley Quest, DVM; Stephanie Clark, PhD; and Michael Johnson//May 8, 2023//
Cannabidiol (CBD) has been increasing in popularity since state governments started legalizing the use of medical marijuana in 1996 and recreational marijuana in 2012. Since that time, there has been a surge of marijuana, hemp, and CBD products marketed to pets. There is science-based evidence indicating that CBD may provide benefits to cats and dogs, yet there are also significant unknowns and possible risks in using these products due to the lack of regulation, lack of long-term safety studies and mixed results on their benefits.
CBD can come from either hemp or non-hemp plants, a hemp plant is defined as one in which the tetrahydrocannabinol (THC) content, the “high” component in marijuana, is less than 0.3 percent. There are three main kinds of CBD: full spectrum, which contains all parts of the hemp plant, including THC; broad-spectrum, which contains multiple parts of the hemp plant excluding THC; and CBD isolate, which is pure CBD. It is essential to read the label carefully to determine the amount of THC in a product, as dogs are more sensitive to THC than humans.1
Pet CBD products come in many different forms, including edibles (treats), oils, tinctures, topicals, and capsules. These different forms can have varying results based on their absorption rates. For example, pet CBD edibles, such as treats, must first go through the digestive tract before reaching the bloodstream, which can delay results. In a recent pet owner survey,2 edibles were found to be the most common delivery method, despite not being the most scientifically-proven form, ostensibly due to the ease of giving the pet a tasty treat.
Some owners prefer CBD capsules, where CBD is usually paired with oil as a carrier. It has been studied3 that the combination of CBD and oil may increase the absorption compared to an edible, as CBD is fat-soluble.
Next, there are CBD topicals, which are applied directly to the skin. These can be useful for targeting a specific issue, such as rashes, hot spots, or painful areas. Lastly, it has been theorized that the best way to administer CBD is with CBD oil in methods that avoid the digestive tract entirely. CBD oil can be rubbed on the ears or gums – this route has had mixed results with some studies showing effective absorption through the skin4 or mucus membranes and others questioning the efficacy.5
Whatever the delivery method, CBD is popular for pets: in a recent study2 surveying 1,448 pet owners, more than 50 percent reported using CBD on their cat or dog. Thirty-eight percent of pet owners used CBD because their veterinarian had recommended it and more than 67 percent claimed that there was a significant improvement in their pet’s health.2
Let’s take a look at what CBD is being used for in pets, and briefly discuss the benefits, the risks and the unknowns.
Any quick Google search will call out CBD for having benefits for improving inflammation, seizures, pain relief and anxiety, particularly in dogs, which have a higher concentration of CB1 cannabinoid receptors, meaning that they are more susceptible to the potential benefits of CBD.2 Owner perceptions have been studied through conducting surveys and in 2016, a survey of 631 pet owners noted that 88 percent of pet owners reported that the use of CBD helped with thunderstorms or fireworks and helped reduce seizures. Roughly 75 percent of the pet owners reported that their pets had improved sleep, reduced inflammation (70 percent), improved anxiety (69 percent) and decreased pain (64 percent).6 A 2019 study out of Canada revealed similar results.7
Inflammation: In response to these and other pet owner perceptions, scientific researchers have begun the quest to study the benefits of CBD in pets. For example, studies observing the impact of CBD on inflammation demonstrated that CBD could assist with discomfort, helped to increase activity in dogs with osteoarthritis,8-11 and could have anti-inflammatory and immune-supporting properties in dogs.12 However, for as many studies that support the beneficial use of CBD for anti-inflammatory diseases, such as osteoarthritis, there are just as many that observed no difference in ease of movement, lameness, and pain associated with osteoarthritis.8,13
Pain Management: Along with osteoarthritis, dog and cats can suffer from pain due to a variety of reasons including, but not limited to, disease, injury, age and genetics; therefore, pain management is becoming increasingly popular in veterinary medicine. A study of CBD supplementation for pain observed improvement in more than 90% of the dogs tested.11 Further, in this study of 32 dogs, 23 began the study already on pain medication, and by the end of the study, 10 of these dogs were able to discontinue their pain medication while another 11 were able to reduce their dosage.11
Seizures: CBD has also been studied for use in seizures: in the human world, the FDA has approved a CBD-based prescription medication for this purpose. From this, it can be extrapolated that similar results would be observed in pets, and in 2019, a study noted a significant reduction in seizures in dogs that were given CBD for 12 weeks.14 While this seems promising, more studies are needed to fully understand the dosage that achieves optimal benefits without increased risks.
Behavior: Studies have noted that CBD interacts with neurotransmitters, one being serotonin, which plays a role in stress, sleep, behavior, and cognitive function. In 2021, a study noted positive behavioral changes in cats and dogs that were given a CBD supplement for 8 weeks.15 More recently, a single dose given 2 hours prior to a stressful situation, such as car rides or separation from the owner, has been shown to help alleviate acute stress.16 With more places becoming pet friendly and people beginning to travel more, the potential calming and cognitive benefits of CBD are welcome and necessary; however, more studies are needed to better understand these features.
Skin: Many dogs and cats suffer from skin issues. Pet owners who have experienced this know it can be extremely difficult to get these conditions under control to provide relief for the pet. With CBD’s potential benefits for pain relief, CBD supplementation for skin conditions has begun. In 2022,17 a study reported that CBD supplementation (without THC) could be beneficial for dogs that suffer from pruritic dermatitis, a very common itchy skin issue in dogs.
The future appears bright, but pet CBD research has just scratched the surface. Despite the continuous barrage of freshly-published studies on the potential benefits to pets, little is truly known about the potential safety and risks associated with CBD supplementation.
There is published literature that notes the adverse side effects in cats and dogs that have been supplemented with CBD. Reported side effects include gastrointestinal upset, such as diarrhea, loose stools, and vomiting, skin irritation, neurological signs, and elevated liver enzymes.1,18,19 These symptoms were noted in both dogs and cats and at varying dosages of orally supplemented CBD.
Neurological and Skin: Other studies show that topically applied CBD cream caused some dogs to experience skin inflammation and itching.18,20 However, the amount of topically-applied CBD that made it to the bloodstream was relatively low, which may suggest that CBD topicals accumulate in the skin without further effect.20 In a study with cats,1 some of those supplemented with CBD had the side effect of shaking their head – this leads to the unanswered question of whether CBD supplementation has negative neurological effects on pets. These same cats also excessively licked the area where the CBD oil was applied, which can be a precursor to developing skin irritations.
Liver Function: Lastly, and possibly the most severe, is the side effect of elevated liver enzymes.8,14,18-20 In veterinary medicine, alkaline phosphatase (ALP) and alanine transaminase (ALT) are two values that are used to help evaluate liver function in pets, with high levels indicating poor liver health. A study in dogs evaluating multiple dosages of CBD showed that dogs that received low dosages of CBD (1 mg/kg of body weight) did not have unusually high levels of the liver enzyme ALP during the study. However, the groups of dogs that received higher CBD dosages (2 mg/kg, 4 mg/kg, and 12 mg/kg) did include individual dogs with increased levels of ALP during the study, some as much as 2.5 times above what is considered to be the normal range. Another study evaluating CBD oil in dogs reported that the dogs given CBD had liver enzyme levels (ALP) that were significantly higher compared to dogs not given CBD after only six weeks.8 This suggests that liver health can be negatively impacted and a veterinarian should closely monitor liver function when giving CBD to pets.8,11,18,19
Longer studies are needed to better determine the risks associated with pet CBD supplementation, and what is the optimal effective and safe dosage.
Product Quality: With the deregulation of low-THC cannabis growing in the US and the increase in the number of CBD products,21 the manufacturing and distribution of CBD-containing products has dramatically increased over the past few years. Since many of these products are considered supplements, they are not subject to the same regulations as other products and enforcement is scarce. To demonstrate the variability of CBD products, 29 commercial pet CBD formulations were analyzed that claimed to contain low-THC cannabis extracts.22 All products were below the 0.3 percent limit of THC, however, the amount of CBD ranged greatly, from 0-88 mg/ml. Four products also tested positive for heavy metals.22 Two of the products did not provide their total CBD concentration and only 22 could provide a Certificate of Analysis of test results to confirm their concentration claim.22 When these 27 products were independently tested by the researchers, it was found that only 10 of the products were within 10% of the concentration on the label,22 meaning what was in the product was not exactly what was on the label.
Dosage: There are no standard guidelines or regulated dosages, so determining the correct amount to give a pet can be extremely confusing. Some products available on the market are recommended at dosages well above the upper range of the doses tested in pets, and this may lead to a toxic effect – this is especially prevalent in dosing smaller animals or those at the lower recommended dose range.
Further, dosages vary greatly between products and even within the same company’s offerings. Some studies recommend dosages of 1-4 mg of CBD per kg of body weight, meaning a 35-pound dog should receive anywhere from 16-64 mg of CBD, while there are products on the market suggesting CBD dosages ranging from 6-400 mg for a 35-pound dog. What may be even more frightening is that many products do not specifically state the amount of CBD in a serving, and the dosage recommendations use words such as “dollop” or “dropper” – ambiguous and variable measurements which can make accurate dosing difficult.
Additional label callouts that were noted were not to give CBD to pregnant or lactating pets, that products for dogs could be [safely] used on cats, and, if the dosage seemed to be “too powerful,” to reduce it. There were, however, no instructions explaining what “too powerful” looks like in a pet, and by how much to reduce the dosage in that instance.
Call to Action
As pet retailers, brands, and manufacturers, you are no doubt aware that this is a good time to be involved with CBD products for pets: sales continue to grow, and the marketplace continues to expand. But you should also know that while many pet parents are sold on these products, many others are not, and even more have yet to give this category a try. When it comes to CBD pet products, consumers run the gamut from enlightened to confused, from compelled to disinterested, from trusting to unsure, and from convinced to incredulous.
In our industry we like to say that we work to do the best things for pet and their owners – when it comes to CBD, some brands clearly back this up, and, sadly, some do not. What do we owe pets and their owners in the CBD space? Where must we collectively be better?
As a starting point, we challenge all involved in this category to endeavor to alleviate consumers’ uncertainty and mitigate their safety risks when it comes to these products, to be precise in dosing recommendations, to conduct accurate and adequate testing throughout the supply chain, to provide Certificates of Analysis (remember that a CoA helps CYA), and to recommend regular veterinarian check-ups for pets being supplemented with CBD (particularly to monitor liver function in long-term use cases). Further, we encourage the industry to get behind safety and efficacy testing for CBD pet products and to work together in establishing consistent industry-wide safe dosing guidelines.