Horse sense or dog trial? The science and law behind CBD petcare products

CBD pet products remain in a grey area in terms of both legality and effectiveness.

In the US an informal structure has emerged to provide something of a pathway to market, as the US Food and Drug Administration (FDA) has not created a formal route for cannabinoid products intended for animals.

The Dietary Supplement Health and Education Act (DSHEA), which permits the marketing of dietary supplements, does not extend to products for animals and the FDA has also made it clear that it “has not approved cannabis for any use in animals, and the agency cannot ensure the safety or effectiveness of these products”.

For animal and pet feeds the position of the Association of Animal Feed Control Officials (AAFCO), which is heavily relied upon by federal and state regulators – as outlined in CBD-Intel’s report on regulation at the federal and state levels, is that hemp and hemp products may not be used in animal feed or pet food in the US. This is because the association says the hemp industry has failed to show any data demonstrating that ingredients derived from hemp are safe and useful in animal food.

Further, the AAFCO specifically said that any CBD-infused products are best treated as drugs as the intended uses are largely associated with drug claims. This means they should not be used as feed ingredients as they could be subject to regulatory action by state agencies.


Seal of approval


In the absence of formal regulation, though, the National Animal Supplement Council (NASC), a trade organisation, has started to work with the FDA, state governments and other agencies to issue a product seal to companies that comply with such conditions as factory audits, adverse event reporting, labelling requirements and product testing. It began approving CBD products for animals last year.

This gives the products some kind of legitimacy, though the threat of FDA regulatory action remains, and there are still restrictions on what can be sold. For example, CBD products intended for animals cannot be described with terms like “treat” or “biscuit” as these would require FDA sign-off as approved food items. Officially such products are considered “dosage-form animal health products”.

There is theoretically a possibility for topical animal products called animal grooming aids that would not require FDA approval but would only be for “cleansing or promoting attractiveness of animals, so not therapeutic. Additionally there is some possibility of “extralabel” prescriptions by vets under certain circumstances.

In the EU, the situation is murkier. Products intended for animals are meant to fall either into the feed category, including items such as treats and pet foods, or the veterinary medicine category, including things like topical flea applications.

Currently, as in the US, almost no approval exists for cannabis-derived medication for animals, seeming to leave the feed category as the only pathway to approval.

The majority will have to go through this category and CBD is treated in the EU as a novel food. Thus foods for animals containing CBD would usually be illegal to sell without prior approval, although this differs from country to country.


Early days for research


In the UK, where the Food Standards Agency (FSA) is creating a path to market for CBD as a food ingredient, the substance is regulated as a veterinary medicine, requiring a prescription.

Nonetheless, despite the legal uncertainty, significant demand for animal-focused CBD products appears to remain and supplies are increasing.

And as interest increases, so too should interest in pet-specific research. Already much research on cannabinoids for humans employs animal trials. But, given the broad range of species kept as pets, together with the complexity of cannabis-derived substances, it is difficult to transpose results from one type of animal to apply to all. And research on cannabis for individual species has hardly begun, let alone robust clinical trials.

But this does not mean there is no evidence whatsoever. The endocannabinoid system is widespread throughout the animal kingdom, and most of what is currently known about cannabinoids has some cross-species application.

For example, a reference for veterinarians exploring therapeutic uses of cannabis draws heavily on existing research in humans and laboratory animals. And work from one dedicated researcher, Lori Kogan, published in 2016 and 2019 shows significant anecdotal support for cannabinoid pet products.


What pet owners think


Kogan and her colleagues surveyed hundreds of dog and cat owners, inquiring about their motivations and experiences treating their pets with cannabinoid products. Most had favourable perceptions of cannabis, with only 7% of respondents in 2016, and similar numbers in 2019, indicating that they felt the substance did not work as well as traditional therapies. While these are subjective perceptions of owners, they are nonetheless telling and demand follow-up research.

So, while studies establishing efficacy for particular species (a long and complicated process) are certainly needed, at this stage greater emphasis might be placed on studies evaluating key differences in safety and pharmacology.

Some work has been done, though most of it has been on dogs. Importantly, though, their cannabinoid receptors are distributed differently from humans’, raising potential problems.

The reason cannabis is so safe for humans is that we have comparatively few CB1 receptors in areas of the brain that are responsible for vital functioning. However, this is not the case for dogs, so substances such as THC that activate these receptors can be toxic (albeit only at relatively high doses). Edible preparations of cannabis can exacerbate this if cannabis is combined with chocolate, the sugar substitute xylitol, or other substances potentially toxic to dogs.

Dogs also have a high concentration of cannabinoid receptors in the cerebellum, which regulates motor functioning. After ingesting THC dogs can experience static ataxia the inability to stand straight or steady.


The dog it was that died


In a paper published in 2012, researchers looked at the association of cannabis legalisation in the US state of Colorado with cannabis-induced toxicity in dogs. Unsurprisingly they found a positive correlation between the number of cannabis licences in a given area and the number of cannabis-induced toxicology reports. For example, two dogs died after heating THC butter – although, importantly, the products in question also contained chocolate.

A couple of studies have also considered potential therapeutic benefits. In 2018 a team at Cornell University looked at creating a possible CBD-based treatment regimen for osteoarthritis in dogs. They found that at a dose of 2 mg/kg, CBD caused a statistically significant decrease in pain and increase in activity, though adverse side effects included increased serum levels of the enzyme alkaline phosphatase.

As with humans, the treatment of epilepsy in dogs is also a promising area. The primary researcher involved in one CBD safety study, Stephanie McGrath, has been conducting clinical trials in this area.

Her study published in 2019 showed promising, if not conclusive, results. She and her colleagues noted a statistically significant median reduction of 33% in seizure frequency in the group of dogs treated with 2.5 mg/kg CBD. However, no difference was observed in terms of the “proportion of responders,” that is the number of dogs displaying at least a 50% reduction in seizure activity.

Given the small sample size and the arguably high bar for treatment success, her findings are not surprising. McGrath and her team are continuing this research.


The sound of fireworks


According to surveys, anxiety is a common reason for giving cannabis products to pets.

One study, published in 2020, looked at how dogs responded to a fear stimulus (the sound of fireworks) following administration of 1.4 mg/kg of CBD for seven days. The paper found there was no benefit, yet questions could be raised over the study’s design: dogs were acquired from a local shelter and given only three days to adapt to their new environment, including just six minutes a day to become acclimated to the testing room.

Another study, published in 2021, found limited evidence for CBD reducing aggressive behaviour in dogs, although again results were not definitive. Sample sizes were small and studies involved relatively short treatment durations.

Research on the use and efficacy of cannabis in dogs is in its early days, but there are certainly signs of progress and further areas to explore. For example, in addition to the studies on cannabis directly, a fair amount of research has been conducted on the molecule palmitoylethanolamide, a substance that in many ways functions like CBD. Studies show it may help to address skin allergies in dogs, suggesting CBD may do the same.

Where cats are concerned, researchers have established the safety of both CBD and THC at relatively high doses. These may be necessary; in a study looking at the pharmacokinetics of CBD in dogs and cats, serum concentrations of CBD in cats were observed to be only 20% of that in dogs, suggesting a possible need for higher dosing.

And in March of 2021 researchers at the University of California, Davis published findings documenting low doses of CBD to be “well-tolerated” in horses, though with no observed anti-inflammatory effects. While few additional studies exist, cannabis has been shown informally to aid in addressing anxiety in horses.


What This Means: As with humans, evidence is mounting about the benefits of cannabinoids for animals. Given the presence of the endocannabinoid system among many animals and the existing evidence base for humans, research should first seek to ensure safety and establish safe dosing regimens, before progressing to more complex clinical trials.

Clayton Hale CBD-Intel science correspondent

Photo: deluxtrade

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