chevron-down Created with Sketch Beta.

Voice of Experience

Voice of Experience Archives

Veterinary Medical Cannabis: Applications and Regulatory Aspects

Robert Silver


  • Evolution of Cannabis Legislation: From California's pioneering medical marijuana laws in 1996 to nationwide changes in 2021.
  • Hemp and CBD Dominance: Hemp legislation in the U.S., defined by low THC levels; CBD's safe use for pets.
  • Veterinary Challenges and Trends: Lack of legislative support for vets in cannabis education; evolving state approaches.
Veterinary Medical Cannabis: Applications and Regulatory Aspects

Jump to:

When California passed the first state-based medical marijuana statutes in 1996, it was soon followed in 2000 by Colorado, Alaska, and Washington State. In 2021, over 24 years since the introduction of medical cannabis in the U.S., there are now 36 states and 4 territories of the US that have similar legislation on their books. Additionally, of these 36 states, there are now 17 states that allow “THC-dominant” cannabis, formerly known as “marijuana,” to be sold or used by anyone over 21 years of age, with no need for a prequalifying medical condition. This cannabis legislation is commonly called “Recreational” versus “Medical.”

In 2014, the U.S. Congress passed legislation, the 2014 Farm Bill, that for the first time, sanctioned the agricultural use of CBD-dominant cannabis, more commonly known as “Industrial Hemp,” or just “Hemp.” By current definition, “hemp” in the U.S. is defined as: “Plants of the species Cannabis sativa L. containing less than 0.3% THC (r-9 tetrahydrocannabinol) on a dry matter basis at the time of harvest.”

By definition and function, “THC” is the intoxicating fraction of the cannabis resin, possessing potent medical activity as well as having recreational value. Plants with rich levels of THC previously were named “marijuana,” and now are named “THC-dominant cannabis.” Hemp levels of THC are below the level of intoxication for most users of hemp. The hemp cultivar is rich in the non-intoxicating, medicinally efficacious fraction of the cannabis resin, called “cannabidiol” or “CBD.”

An alternate term for hemp is “CBD-dominant cannabis.” Hemp plants are regulated at both the federal and state levels, reflective of the more recent Farm Bill 2018 and Hemp Farming Acts. THC-dominant cannabis is still a Schedule I on the list of Controlled Substances and is federally illegal, even if legal at the state level. CBD derived from THC-dominant cannabis is still considered a Schedule I by the U.S. Drug Enforcement Agency (DEA). Predictions are that the U.S. will soon legalize THC-dominant cannabis at the federal level, not unlike our Canadian neighbors to the north, who legalized THC-dominant cannabis federally in 2018.

It is important to note that ALL of this legislation sanctioned the use of cannabis only in the human species. Subsequent to the legalization of THC-dominant cannabis in California in 1996 (and probably before legalization), pet owners have been experimenting to see if THC-dominant cannabis and/or CBD-dominant cannabis has any value when used in their pets. From that early beginning in the mid-1990s to now, pet owners (they prefer to be called “Pet Parents” BTW) have found huge successes when using CBD for epilepsy, pain and arthritis, digestive problems, anxiety, and even diabetes and cancer.

Dogs (Canis familiaris), amongst all the many species of mammals, are exquisitely sensitive to the adverse neurological and cardiovascular effects of THC when they have not been exposed to it in the past. There is anecdotal evidence that secondhand smoke in households that inhale cannabis may in fact “tolerize” dogs to THC’s adverse effects. “Tolerance” is defined as a developed resistance to some or all of the effects of a substance with continued use over time. Dogs who are exposed to sufficient concentrations of THC in cannabis will exhibit a unique and distinctive neurologic behavior following its ingestion that is only exhibited in dogs that have been given THC.

This behavior was first described in the late 1890s by a British medical doctor, one of the first in the developing field of pharmacology. He coined the term “Static Ataxia” to describe its neurologic manifestation. This behavior is so unique to the dog and specific to THC, that prior to the development of analytical testing for THC when a smuggled shipment of cannabis was intercepted, they would feed it to a dog to confirm that it was in fact THC-dominant cannabis. If the dog reacted with Static Ataxia after being fed some of the recovered cannabis, it was legally admissible, and they could convict on that evidence. Fortunately for dogs, we now have analytical instruments that don’t subject them to this potentially harmful testing process.

Although there has not been a single recorded event where a human being died from an “overdose” of THC, there are a number of events recorded where dogs have died from being given excessive amounts of THC. This is because dogs have an overabundance of THC membrane receptors (we now call these Cannabinoid Receptor 1 or the CB1 receptor) in their cerebellum, medulla oblongata, and brain stem which govern balance, thermoregulation, cardiac and respiratory rates. Commonly THC is found in toxic-to-dog concentrations in edibles designed for humans, originating from commercial dispensaries or pet parent kitchens. These edibles often are made with chocolate and other ingredients that are toxic to dogs, thus providing a co-toxicity to these dogs, sufficient to affect heart rate and temperature regulation and potentially fatal to an individual.

This potential toxicity brings up another point, which is that in states that allow medical cannabis or recreational cannabis, any person with a 21 or older ID can walk into a dispensary and purchase a product that, if they gave it to their pet, or if the pet (or child) accidentally ingests this product, the pet or the child may need to be seen at the Animal ER or Human ER for adverse reactions. Depending on the state where this occurs, animal abuse or child abuse charges may be filed. There are no legal constraints placed on the sale of human cannabis products to pets in the dispensary context.

Dispensaries are the only place in the U.S. where cannabis products containing substantial THC levels, that are greater than found in hemp products, are sold. THC is potentially problematic to dogs. CBD on the other hand has been found in multiple peer-reviewed published studies to be safe at the dosages commonly used across the board for dogs and cats and is much more widely available than THC products which are restricted for sale in dispensaries only. CBD products are widely available online, and can be found in roadside stands, much like Jerky Treats, or in gas stations or hardware stores.

When the state legislatures were crafting their legislation providing a legal pathway for humans with medical conditions to use THC-dominant cannabis, or to use it “recreationally,” no thought was given to providing legislative language that would allow veterinarians to recommend THC-dominant cannabis. No legislative language was created that would allow veterinarians to dispense CBD products for their patients, or to even recommend that their clients try CBD for their pets.

This lack of legislative sanctioning allowing veterinarians to be involved in the medical cannabis “conversation” (certainly our pets aren’t interested in its recreational aspects!) is problematic. Pet owners are not getting information from their vets about whether it’s OK to use CBD for their pet’s problem and specifically whether CBD might interfere with other medical treatments their pets might be undergoing. Many times this is because the states prohibit vets from discussing cannabis or hemp with their clients, even when asked by the client for some help. Pet owners are not getting information from their vets about how to use THC safely with their pets, or if the use of THC is indicated for that patient. Usually, a vet will find out their client is using THC on their patient when they get the referral letter from the Animal ER that their patient had been admitted for a THC “overdose.”

In some states, the state veterinary medical board has been admonishing veterinarians not to discuss cannabis at all with their clients or face reprisals from the Board. This is even when pet owners can easily go to recreational dispensaries and buy potentially toxic products for their pets, or even find CBD products in gas stations, but veterinary practices are forbidden from selling hemp-based CBD.

As of this writing, three states (California, Michigan, and New York), have inserted language or are considering language in their cannabis statutes that allow veterinarians at least to discuss the use of cannabis with their pets, if not actually recommend a cannabis product. This is a good trend that we are seeing with these states’ legislations. I’d like to see each state with legislation allowing human physicians to recommend cannabis following an examination and consultation to also allow veterinarians to do the same. THC is not toxic, but is a medically effective component of cannabis, and can be safely introduced to a dog, with veterinary supervision.

The veterinary medical boards claim that without FDA regulation and safety studies (of which there are numerous, all pointing to the safety of CBD),[6-9] it is a question of standards of medical care to use a substance for which there is inadequate evidence of safety and efficacy. The safety studies I’ve reviewed are definitive regarding safety. The efficacy studies are being published for arthritis and refractory epilepsy, and they provide good guidance for dosing and what side effects to expect at the higher doses being given in these studies. The established dosages for the published studies for arthritis are much higher than what is routinely used in the field by veterinarians and pet parents, and higher dosing is always associated with the potential of greater side effects.

The American Veterinary Medical Association ( ), and most state veterinary boards, recommend against discussing and dispensing CBD products to their clients. Many vets ignore that advice because they see the potential for CBD to treat better and more safely than the existing pharmaceutical choices. These vets are taking a risk with their licenses because they have seen the value of CBD in their patients and consider not using that therapeutic to be a violation of standards of care. I personally side with the practitioners. I think the veterinary medical boards are still caught up in the stigma of the 70 years of prohibition of the use of cannabis in the U.S. and are not serving their constituents but instead covering their butts to avoid liability, versus helping vets treat their patients better.

The details expressed in this document of the current regulatory environment for pet cannabis are neither well known by the general pet-owning public, veterinarians in general, nor by the legal community. Thus I am pleased to be able to address this problem to this group who are in the best position to help bring the safe and effective use of medical cannabis to the veterinary community, for the good of our pets, and for the good of our community.