The Highs and Lows of Medical Marijuana for Dogs

By Narda Robinson, DO, DVM

The cannabis trade, also known as “cannabis-ness,” has evolved from a budding homegrown operation into a blossoming industry, projected to top $10 billion in the next five years,1 signaling the emergence of “Big Marijuana.”2

But, medical marijuana for dogs?

Whether or not veterinarians are ready, it’s already here. Certainly, rigorous scientific research should precede its sale for the canine consumer, but the public isn’t waiting. Customers are purchasing products laced with cannabis for dogs or sharing some of their own stash with their cats.

Veterinarians may rebuke the notion, dismissing it as “untried, unproven and unregulated.”3 A few brave, outspoken professionals have taken a more proactive approach. One created a cannabis tincture called “Canine Companion,” designed to relieve pain, inflammation and other cancer-related or end-of-life health issues.4

Testimonials favoring veterinary cannabis, even on the AVMA website, speak highly of the improvements they see such as rapidly replenishing quality of life and restoring mobility to animals otherwise unwilling or unable to ambulate. In addition, it has restored appetite and reduced reliance on mainstream pharmaceuticals that the animal could not tolerate.5

Taking a Closer Look

Given the seemingly immense potential of “pot for pets,” why does simply raising the issue generate a recoil response from veterinarians? Some cite the shortage of studies, though more research exists for the pharmacology of cannabis than for many “natural” products in common use.

Instead, what may be making veterinarians more hesitant to go on record as “pro for pot” relates to the near-epidemic reports of marijuana toxicosis in emergency veterinary facilities.6

The incidence of unintended exposure is increasing as the legalization spreads throughout the United States.7 Veterinary hospitals in Colorado, a state pioneering marijuana legalization, have witnessed a startlingly steady increase in animals admitted for marijuana poisoning.8

Even before laws passed allowing sales for recreational purposes, the number of dogs presenting with marijuana toxicosis had quadrupled. Likely contributing factors beyond increased availability include heightened awareness among clinicians of the signs of poisoning, population shifts (e.g., marijuana “tourism” and immigration) and more willingness of clients to seek veterinary assistance for this condition.9

The problem isn’t the plant; it’s people.

They may induce intoxication in dogs unintentionally by disposing of cannabis-containing edibles in the trash10 or by intentionally exposing them to tinctures, vapors and even homemade dog biscuits.11
Depending on the dose and route of administration, the consequences of cannabis can be catastrophic, causing toxicosis in as soon as 30 to 60 minutes.

Manifestations include agitation, ataxia, hyperexcitability and even seizures.12

Dogs may also exhibit hypersalivation, depression, hypothermia and bradycardia, among other signs. Occasionally, dogs die due to tetrahydrocannabinol (THC) overdose.13

Given that no specific antidote exists for THC poisoning, treatments target general, supportive care. Some dogs ingest multiple other drugs, legal or illegal, further complicating the picture and risking confiscation of the animal by authorities due to animal welfare or other concerns.14

“Whole Plant” Constituents

As guardians of animal health, welfare and public health, veterinarians occupy the unique position of working with both sides of the issue – human and veterinary – through a One Health dimension. While information regarding the metabolism and distribution of active cannabis components remains far from complete, seminal research provides some guidance.

Many of the untoward effects of commercial preparations for humans when taken by nonhumans stem from the high concentration of THC – the psychoactive component of marijuana.

Developing a veterinary version for health promotion may require modification of the “recipe” by introducing a more natural, balanced palette of cannabis constituents. Practicing plant-based medicine or medical herbology calls for consideration of whole-plant chemistry; this applies to marijuana as well.

Certain cannabis constituents have cardiovascular activity but few behavioral effects.15 Some may actually offset the profound cardiovascular depression seen with THC.16 A full investigation of the panoply of cannabis characteristics may pave the way to healthful, rather than harmful, medical marijuana preparations for veterinary species.

Moving Forward

How does the landscape need to change to foster interest in, rather than frighten researchers away from, translational investigations?

Clearly, one issue involves the categorization of marijuana as a Schedule I substance. Schedule I of the Controlled Substances Act comprises a tightly restricted category reserved for drugs with “no currently accepted medical use.”17

Schedule I substances also require that the product have a high potential for abuse and lack of accepted safety under medical supervision. None of these unquestionably applies to marijuana.

Decade after decade, advocates of less restrictive marijuana laws have petitioned the Drug Enforcement Administration to rethink the scheduling of marijuana, thus far unsuccessfully. Each state maintains similar classification lists but now that more are decriminalizing cannabis, state and federal laws are coming into conflict.

No wonder human and veterinary researchers and clinicians have been fearful to pursue joint research!

Fortunately, in light of the growing acceptance and glowing reports of medical benefits, many large organizations are calling for change.

Reportedly, the American Medical Association, the National Association for Public Health Policy and the American Public Health Association have all been urging the federal government to reschedule marijuana to a level that would stimulate research and new cannabinoid-based formulations.18

The AVMA has called for veterinarians to join the debate. In this author’s opinion, veterinarians should not only participate in the debate, but also lead discussions, direct dialogue and promote proper use, public health protection and consumer education.

Dr. Robinson, Dipl. ABMA, FAAMA, oversees complementary veterinary education at Colorado State University.