Should cannabis derived products be used for pets?
Cannabis used to be an illegal drug that most people would never encounter. These days, not only is it in widespread use amongst young people, but even political leaders confess to having sampled it. And derivatives of cannabis are now being touted as medical treatments for a range of conditions. People are even talking about using cannabis derivatives to treat dogs.
This is a complex area that is much misunderstood by the general public. While there is some evidence that some of the constituents from Cannabis plants can help certain conditions (such as arthritis, epilepsy and nervousness), this has not, to date, been supported by detailed and extensive studies. This means that licensed products are not available, so your vet cannot prescribe these types of medications in the same way as they can use standard, well established medical products.
Yet people can go into some health food shops, or online stores, and buy these products for themselves. The problem is twofold: first, there are health risks to pets, and second, many products have not been proven to be effective, so pet owners may be wasting their money.
The cannabis plant (Cannabis sativa) has been used as a recreational drug by humans for many years. The active component is tetrahydrocannabinol (THC), but research has shown that the plant contains over 400 other distinct compounds. The product that is most widely discussed in recent times is called Cannabidiol (CBD). In contrast to THC, CBD does not have any psychoactive effects: it is only used for its medical properties.
In humans, CBD has been used as an anticonvulsant to treat seizures, as well as for anxiety, nausea and some types of psychosis. Some other cannabis-derived products are claimed to have other helpful effects: Cannabichromene (CBC) can act as an anti-inflammatory, while Cannabigerol (CBG) is said to have anti-cancer and antibacterial activity.
If these products were normal herbal derivatives, it would be complicated enough: they could only be sold as ‘ health food supplements’ without making medical claims until sufficient research had been carried out to demonstrate that they had a safe, reliable therapeutic effect.
The extra complication with cannabis-derived products is that in Ireland cannabis is a controlled drug (i.e. it’s illegal to possess, sell and use it). Specifically, the psychoactive components of cannabis (such as THC) are illegal, which makes the complete plant illegal. However, if CBD or other components of cannabis can be extracted as pure products, they are not illegal. One of the challenges for those marketing these products is that they need to do complex laboratory analysis to prove that there are no controlled cannabinoids included.
The veterinary medicines regulator (the Health Products Regulatory Authority - HPRA) does not list any CBD products for pets, which means that to date, it is illegal to sell, supply or advertise CBD products for pets, with or without specific treatment claims. There are currently no authorised CBD products for animals in Ireland or the UK.
Apart from these legal issues, there are other reasons why owners should be cautious about using CBD in their pets. Even though CBD does not have psychoactive effects, it still has the potential to cause harm to pets, and this can happen invisibly. Typical issues include liver damage, interference with the metabolism of other drugs, and side effects that can include drowsiness - or conversely, irritability and agitation - as well as gastrointestinal upsets.
Even after this explanation, I suspect some people will still consider using CBD oil in their pets. So for the sake of completion, it’s useful to share some of the scientific research that has been carried out on its possible uses. There is a phenomenon known as “the caregiver placebo effect” which means that it’s easy for pet owners to believe that a product gives benefit to their pet, even when nothing may be happening in reality. The only way to know whether a drug really works is through proper, randomised, placebo controlled trials. Until these have been completed, it’s impossible to state the efficacy of a new product with any confidence.
One study on CBD in 2018 involved 16 dogs with arthritis. This small study identified a small but statistically significant decrease in pain and an increase in animal activity in treated pets compared to untreated animals. However the products used included a small amount of THC (the psychoactive part of cannabis) as well other cannabinoids, so this is different to pure CBD products. So what should owners do to help pets with arthritis? There is strong evidence for a range of effective treatments, ranging from lifestyle measures like controlling excess body weight and maintaining moderate exercise, to nutritional options like special diets enhanced with essential fatty acids, to pharmaceutical options like licensed non-steroidal anti-inflammatory medication which can be given every day to relieve pain.
The best advice for pet owners is to talk to their own evidence-based vet first, rather than trialling unproven “alternative” therapies on their own without the safety of veterinary supervision.