As cannabidiol (CBD) is gaining mainstream popularity for the use of people suffering from a wide variety of conditions, it is only natural that pet owners have started to wonder if they should be giving these products to their pets as well.
But what is the science behind CBD oil for pets? Are medical marijuana and cannabinoid products safe for pets, and is there science to support administering cannabis products to our pets?
In this article we will examine these questions and more to help you come to your own conclusion about the use of CBD products for your beloved dogs and cats.
Cannabis Sativa and The Endocannabinoid System
For thousands of years cannabis has been used in traditional medicine, and not exclusively due to its psychoactive effects. It was used for the treatment of a wide range of disorders, including headache, bacterial infections, rheumatic pain, malaria, and diarrhea. (4)
In spite of this history, the psychoactive effects and concern over the addictive potential of this herbal medicine has led to cannabis and its products lacking legal status.
As the legal status of marijuana has started to loosen, scientists and the community at large have begun to have more freedom in experimenting with and learning more about this traditional herbal medicine.
Cannabis sativa is one plant that encompasses both marijuana plants and industrial hemp plants. What differentiates these two is how they were bred, which has led to a difference in the chemical compounds contained in each.
Marijuana plants have a higher percentage of THC (tetrahydrocannabinol), the compound that is largely responsible for the “high” that users get from smoking marijuana.
Hemp plants have a lower percentage of THC and a higher percentage of CBD (cannabidiol), a compound found in cannabis plants that does not have a psychoactive effect.
Both THC and CBD belong to a class of over 80 compounds in cannabis known as phytocannabinoids. These phytocannabinoids are capable of interacting with the endocannabinoid system (ECS) found in humans, mammals, and even some other animals, lending to many of the recreational and therapeutic properties of Cannabis sativa.
The ECS is a lipid signalling system made up of cannabinoid receptors, endocannabinoids, and enzymes involved in the biosynthesis or degradation of these endocannabinoids.
In order to better understand this system and the studies surrounding it, it is helpful to understand the different kinds of cannabinoids.
Endocannabinoids are those that are created within the body, phytocannabinoids are those found in plants, and synthetic cannabinoids are a class of chemicals that humans have created that act primarily through binding with the cannabinoid receptors in the body.
Two of the most well-researched endocannabinoids are 2-AG (2-arachidonoylglycerol) and anandamide (AEA).
The CB1 cannabinoid receptors are found primarily throughout the central nervous system (CNS) in areas of the brain involved in pain modulation, memory, and movement. They are also found in other peripheral tissues, including the pituitary gland, heart, lungs, bladder, adrenal gland, reproductive tissues, sympathetic ganglia, gastrointestinal tissues, and immune cells.
CB2 receptors are primarily found in the immune tissues and cells, although they have also been found in the spleen, tonsils, and the CNS.
Cannabis sativa and Pets
With the findings from over 100 controlled clinical trials since 1975 involving cannabinoids for a variety of therapeutic purposes, the legality of medical marijuana has expanded not only in the US but in other countries as well.
This expansion in knowledge and hope of therapeutic relief for a variety of symptoms arising from multiple disease states has led animal lovers and veterinarians to wonder, can Cannabis sativa and its constituents provide help for our dogs and cats too?
Largely due to legal concerns, there has been very little research regarding CBD oil or any other cannabinoid product in pets. That said, there are many theories backed up by research that can help individuals to make an informed decision regarding CBD products and their pets.
All vertebrates have an endocannabinoid system, however the ECS of each type of mammal does differ.
Studies thus far have only elucidated a small percentage of the mechanisms of action of cannabinoids as this process is quite complex.
CB1 activation results in retrograde inhibition of the neuronal release of dopamine, serotonin, GABA, acetylcholine, glutamate, histamine, glycine, cholecystokinin, D-aspartate, and noradrenaline.
CB2 receptors are involved in inflammatory processes, which are intricately tied to immune function. Activation of CB2 receptors inhibits proinflammatory cytokine production and boosts the release of anti-inflammatory cytokines.
To further complicate matters, some cannabinoids are not only capable of acting upon the cannabinoid receptors, but exert effects through additional pathways. One of these is the cannabinoid impact at vanilloid or serotonin 5-HT3 receptors.
With these wide-reaching effects of cannabinoids, it is not surprising that human studies have found therapeutic potential of cannabinoids in the treatment of a variety of disorders, including anxiety, headaches, inflammation, cancer, autism, multiple sclerosis, mood disorders, asthma, Alzheimer’s disease, epilepsy, asthma, pain management, arthritis, and Parkinson’s disease, among others. (4)
When it comes to understanding the effects of cannabinoids on animals the science comes from experiments conducted on animals in preclinical trials, including rats, mice, and guinea pigs.
The lack of research aimed particularly at household pets, such as cats and dogs, is because there is no state where it is legal for veterinarians to prescribe these products to pets. This legality extends to research, leaving pet owners to draw their own conclusions regarding CBD oil products and the effect on their pets.
Here we will review the very limited studies directly surrounding dogs, cats, and the ECS.
Of the companion animal studies, one study on dogs examined the effect of topical administration of THC to the eyes of dogs to determine the effect on measures related to glaucoma. (4)
12 normal dogs were randomized into a placebo eyedrop group and a 2% THC eye drop group. Intraocular pressure (IOP) and aqueous humor flow rate (AHFR) measures were taken at multiple points before treatment, and then dogs were given eye drop treatment once every 12 hours for 9 doses. IOPs and AHFRs were measured following the final treatment. Following 7 or more days of a washout periods, dogs were given the alternate treatment in the same eye and measurements were taken. (5)
Mean IOPs were significantly decreased following THC eye drop administration but not with the control treatment. A significant change from baseline of AHFRs was not seen for either treatment.
These findings led researchers to conclude that a 2% THC ophthalmic solution resulted in a moderate reduction of mean IOP in normal dogs, leading to the basis for further research in determining the efficacy of THC for dogs with glaucoma.
Similar glaucoma experiments on a variety of cannabinoids were conducted on rabbits and monkeys with promising results. (4)
Additional potential promising uses for cannabinoids in pets include treatment for pain, inflammation, dermatology uses, and oncology uses. (4)
While no companion animal studies have been carried out, researchers published a review in 2007 in the Veterinary Journal outlining the possible mechanism for an endogenous fatty acid amide analogue of the endocannabinoid AEA in inflammation, pain, and tissue protection. (6)
The authors believe that palmitoylethanolamide (PEA), which has been demonstrated to enhance AEA activity, may represent a novel approach in veterinary medicine aimed to control tissue damage, pruritus, inflammation and pain thanks to its anti-inflammatory and antinociceptive effects.
The Impact of PEA on Dermatology in Cats and Dogs
In a 2001 study published in Veterinary Dermatology, 15 cats with eosinophilic plaques or eosinophilic granulomas were treated with substance PLR 120, a PEA analogue. (7)
Researchers found clinical improvement in lesions in 10 of the 15 cats, supporting the theory that PLR-120 could be an effective treatment for these dermatologic disorders.
Another study examining the effects of PEA in dermatological disorders with mast cell hyperactivity was published in 2010 in Veterinary Immunology and Immunopathology. (8)
Histamine, tumor necrosis factor-alpha, and prostaglandin D2 levels induced by canine anti-IgE from mast cell skin biopsies from 18 dogs were significantly inhibited by PEA.
The same researchers found that PEA helped reduce the cutaneous allergic inflammatory reaction in six Beagle dogs. (9)
Tumor Growth in Canine Osteosarcoma Cell Inhibited by Synthetic Cannabinoid Agonist
In regards to oncology, which is the study and treatment of tumors, an in vitro study was published in 2013 in Veterinary Medicine: Research and Reports. (10) The researchers found that WIN-52,212-2, a synthetic cannabinoid agonist, demonstrated efficacy as an inhibitor of angiogenesis in canine osteosarcoma cell lines.
While much more research is needed, particularly in vivo research, these findings suggest a potential therapeutic use of cannabinoid receptor agonists in the treatment of cancer in dogs.
Additional studies have reported antiemetic (preventing vomiting) activity of nabilone, a synthetic cannabinoid receptor agonist, in cats following anti-cancer drug treatment, and the antiemetic activity of THC in ferrets. (4)
So does CBD Oil Help Pets?
The answer to this question has not been sought in published studies on animals, leaving pet owners to experiment on their own to see if they see any benefits.
The studies conducted thus far on rats, humans, and in the few cat and dog studies outlined above do demonstrate a role of cannabinoids in a wide variety of pathologies. With cats and dogs also having an endocannabinoid system, it is likely that cannabidiol and other cannabis-derived products will have some effect on pets.
Countless reports of CBD helping with pain, cancer, nausea, skin conditions, and other health conditions exist in forums and articles online, however we are all still anxiously awaiting solid scientific studies to help offer confirmation and guidance when it comes to CBD and pets. (11)
Words of Caution Regarding Cannabis Sativa and Animal Treatment
One thing that is known is that dogs and cats are more sensitive to THC than humans are. While there does not appear to be a lethal dose of THC in humans, there is in other mammals.
In dogs, for example, studies show that the THC in marijuana may lead to toxic and lethal effects if more than 3g/kg of body weight is consumed. (1)
Luckily the products out there for pets are THC-free, rich in CBD that does not have this same effect, however this demonstrates the difference in the effect of cannabinoids in dogs and cats versus humans.
Because of this heightened sensitivity, it is recommended to start at low dosages for any CBD product and closely monitor responses.