The endocannabinoid system (ECS) is not only present in a human body. There are a vast number of animals that have ECSs as well. It can be found in vertebrates (mammals, birds, reptiles and fish) as well as invertebrates (leeches, mussels, nematodes and others).
Just like opioid receptors that are activated by opioid peptides called endorphins, all mammals have cannabinoid receptors that can be activated by endocannabinoids. Endocannabinoids are compounds that are formed naturally in any mammal and trigger a variety of effects. The most common representatives are anandamide (AEA) and 2-archidonoyl glycerol (2-AG).
Figure 1: Structures of AEA (left) and 2-AG (right).
Another group that can activate endocannabinoid receptors are phytocannabinoids – structurally related compounds that derive from Cannabis plants. Among them, the mostly recognised and studied are cannabidiol (CBD) and tetrahydrocannabinol (THC).
Figure 2: Structures of CBD (left) and THC (right).
In the scientific literature there is a large and increasing number of published studies on the effects of CBD and THC in pre-clinical trials on animal models, such as mice and rats, and clinical trials on healthy human volunteers as well as patients with various diseases.
On the other hand, the scientific literature reveals that papers dedicated to the beneficial effects of CBD and THC on animals with certain diseases are relatively scarce. The outcomes of one clinical study on osteoarthritic dogs treated with CBD are described below. In addition, the research into what type of dietary supplements are commonly used for dogs with epilepsy is also discussed.
Routine, nonsteroidal, anti-inflammatory drug (NSAID) treatments are mainly effective treatment for osteoarthritis in dogs, but come with potential side effects, such as kidney or gastrointestinal pathologies. As the ECS system is known to play an important role in the modulation of pain and inflammation, phytocannabinoids like CBD, which is famous for its anti-inflammatory effects and pain relief, represent an attractive option to improve the conditions of osteoarthritis in mammals, including dogs.
Gamble and co-workers (2018) investigated the safety and clinical efficacy of CBD in osteoarthritic dogs. Sixteen dogs with clinically confirmed osteoarthritis received a full-spectrum CBD oil that contained mainly CBD, but also other phytocannabinoids such as an acidic form of CBD (CBDA), cannabigerol (CBG) and traces of THC.
The dogs were divided into two groups, one group received a lower dose (oil with 2 mg CBD/kg body weight of animal) and the other group received a higher dose (8 mg CBD/kg body weight). Each treatment lasted for 4 weeks and 2 weeks of washout period without receiving any CBD oil. The trial was conducted under the supervision of veterinarians and dog owners.
Administration of the lower dose of CBD oil resulted in a significant decrease in pain. Moreover, an increase in the dog’s activity during the CBD treatment was also observed, with no side effects reported. The authors concluded, based on the results, that oil with 2 mg of CBD per kg of the animal’s body weight, administered twice daily, increases the comfort and activity in dogs with osteoarthritis.
Epilepsy is a pathophysiological condition common in humans. It is also the most common chronic neurological disorder in dogs. Certain diets have been shown to positively impact on the seizure activity in dogs with confirmed epilepsy.
Berk and co-workers (2018) investigated how the owners of dogs with confirmed epilepsy treat their pets in order to improve their animals’ lives. The study was broad and included questions like what type of supplements the owners use (if any), why do they administer it to their pets and what are the reasons that they stopped using such products. The most used supplements were found to be fat or oil products, among which 42% of these were CBD/hemp-derived oils. This is a relatively high percentage, but is there any proof of CBD’s efficacy in the treatment of dogs with epilepsy?
Well, the information in the literature is scarce, but there is one study by McGrath and co-workers (2019), who investigated the effects of CBD on dogs with confirmed idiopathic epilepsy. The term ‘idiopathic’ means that the cause of the seizures is not known. The authors investigated the anti-epileptic effects (reduction of seizure frequency) of CBD oil when administered in combination with a conventional anti-epileptic treatment. The CBD oil contained a full-spectrum hemp extract with CBD as the main active ingredient and other cannabinoids such as cannabinol (CBN), cannabigerol (CBG), cannabichromene (CBC) and THC. The study was conducted on 16 dogs and lasted for 12 weeks. The dogs were administered a regular therapy with an anti-epileptic treatment or the regular treatment in combination with the administration of 2.5 mg CBD/kg of the animal’s body weight twice daily.
The results revealed a significant reduction in the seizure frequency for dogs treated with CBD oil; however, the proportion of responders was similar between the groups. The authors concluded that based on the obtained results, additional research is warranted to determine whether a higher dosage of CBD would be effective even without the conventional anti-epileptic treatment.
The revised studies revealed a good safety profile for the administered full-spectrum CBD oil for dogs. However, like humans do not always react in the same manner to CBD, also your pet might be affected by CBD in a different way. Therefore, we advise you to consult a veterinarian before starting to administer CBD oil to your pet.
Gamble et al. (2018): Pharmacokinetics, Safety, and Clinical Efficacy of Cannabidiol Treatment in Osteoarthritic Dogs (available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6065210/)
Berk et al. (2018): Investigating owner use of dietary supplements in dogs with idiopathic epilepsy (available at https://pubmed.ncbi.nlm.nih.gov/30064067/)
McGrath et al. (2019): Randomized blinded controlled clinical trial to assess the effect of oral cannabidiol administration in addition to conventional antiepileptic treatment on seizure frequency in dogs with intractable idiopathic epilepsy (available at https://pubmed.ncbi.nlm.nih.gov/31067185/)