Could cannabis play a role in geriatric, palliative veterinary care?

The focus of palliative and hospice care is to achieve the best quality of life possible for the patient and the family

Source: Sarah Silcox, DVM, CVA, CVSMT, Veterinary Practice News

The focus of palliative and hospice care is to achieve the best quality of life possible for the patient and the family. Sometimes, this can be difficult for doctors who are trained so well in what we “can do,” that it can be hard to let go and focus instead on what we “should do.” Part of that goal should include finding ways to best support our patients in a way that also strengthens the human-animal bond and puts the least stress on both parties. With people spending more time at home due to COVID-19, many pet owners perhaps have more time to provide nursing care for their aging or ill animal companions. As we seek new ways to help support aging and ailing pets and their loving families, medical cannabis holds considerable promise and is a therapy that may be considered.

For millennia, people have used the cannabis plant as a source of medicine, not only for themselves, but for their animals.¹ In recent years, there has been a resurgence of interest in its medical applications—again, not just for people, but for the animals with whom we share our lives. Although various states have legalized recreational and/or medical marijuana, veterinarians are not yet able to legally prescribe, dispense, or recommend most cannabis-based therapies. That said, change is afoot. In 2019, California became the first state to give veterinarians legal protection to discuss the use of medical cannabis for their animal patients in their licensed practice. If history is any indication, other states will likely follow suit. As such, it is incumbent upon us to have a basic understanding of how cannabis works, and the conditions where it shows the most promise.

How Cannabis Works (ECS System)

The cannabis plant has been found to contain more than 400 chemical compounds, including over 100 cannabinoids, 120 terpenes, as well as phenolic compounds, bioflavonoids, and antioxidants. The composition of each plant’s compounds can vary significantly depending on several factors, including the cultivar strain, growing conditions, harvest time, drying and curing, and the final processing methods.

We are only just beginning to understand how these many compounds work within the body, and how they interact with each other to produce a specific effect. The endocannabinoid system (ECS)—which is found in all vertebrates (as well as some invertebrates)—may well be the largest receptor system in the mammalian body. The two primary cannabinoid receptors, CB₁ and CB₂, along with the many other receptors that work within the ECS, can be found in almost every organ system.

1) Chronic pain, including pain from osteoarthritis: Chronic pain, and particularly pain from osteoarthritis, is a condition most practitioners deal with on a daily basis among our senior patients. When treatment options are exhausted or become cost- and/or time-prohibitive, unmanageable chronic pain can lead to the humane euthanasia of a beloved pet.

Current therapeutic options have typically included the use of nutraceuticals, NSAIDs, gabapentin, tramadol, other opioids, amantadine, acupuncture, massage, photomodulation (i.e. laser therapy), and rehabilitation.

Clinical studies have shown cannabis can reduce pain and improve mobility in animal studies of osteoarthritis, including several recent papers assessing the effectiveness of CBD-based products on dogs with this condition.

What makes cannabis so unique to many other treatments is its potential to address arthritic pain through multiple mechanisms, including chondroprotection, anti-inflammatory action, and analgesia.

2) Cognitive dysfunction and anxiety: Anxiety in senior pets can be due to many causes, including pain, a reduction in hearing/vision that can make them feel less secure, and cognitive changes.

Pet owners using hemp-derived CBD products for their pets have reported that age-related behavioral changes and general anxiety are some of the most common reasons for using cannabis. They also report a high degree of satisfaction with the results (93 percent and 83 percent, respectively, reported cannabis products helped either “a moderate amount” or “a lot” for the given condition).

3) Cancer: Of all conditions discussed, perhaps the one that has attracted the most attention is the use of cannabis in the support and treatment of cancer. Consider this: A PubMed search for “cannabinoid cancer” produces 1,541 results. Yet, despite all this research, we are only beginning to scratch the surface on how we can best use cannabis clinically, and in what conditions. Indeed, the research shows various cannabinoids and terpenes can have a direct effect on tumor growth through a multi-targeted approach, as well as providing palliative support for many of the symptoms accompanying both cancer and cancer therapy.

Cannabis extracts, as well as CBD and THC isolates, have been shown through a variety of both in vivo and in vitro studies to have anticancer properties in various neoplastic conditions. They exert their antineoplastic effects by promoting apoptosis, reducing tumor cell proliferation, and improving response to some chemotherapeutics and radiotherapy. The response varies depending on the type of cancer and the composition of the extract used, but nonetheless cannabis-derived therapies show tremendous promise as part of oncology treatment.

Even without targeting a resolution of cancer itself, cannabis also has proven beneficial in reducing some of the symptoms associated with this disease. Through various pathways, compounds found within cannabis can help manage pain, reduce nausea (including chemo-induced nausea), improve appetite, allow improved sleep quality, and reduce anxiety and depression.

Sarah Silcox, DVM, CVA, CVSMT, is a founding director and current president of the Canadian Association of Veterinary Cannabinoid Medicine (CAVCM), a national nonprofit corporation founded by a group of veterinary professionals.