The first published research related to cannabis and companion animals appeared in 1899 in the British Medical Journal. Written by English physician and pharmacologist Walter E. Dixon, the article included Dixon's observations on the response of dogs and cats to high-THC cannabis. Since that time, most medical cannabis research has focused on humans, although, more recently, benefits for animals are being explored.
In the last couple of years, veterinarians have re-discovered the benefits of cannabis to treat medical conditions in pets, and we have seen successes in treating many of the same diseases from which humans suffer. Pets suffering from pain, inflammation, arthritis, cancer, seizures, and digestive issues have all found relief through the use of medical cannabis. Dosing considerations, however, must be taken very seriously. Due to their small size and physiological differences, pets cannot be dosed like "small humans.”
Annie was a two-year-old black Labrador retriever brought to my office by her owners in search of an effective treatment. Annie had been diagnosed with epilepsy. She was having multiple seizures per day despite being on two different anti-seizure medications.
Epilepsy is occasionally seen in dogs. The seizures normally begin when the dog is young (two or three years old) and can range in severity from very mild to quite severe. Annie's seizures were relatively mild, but she was having multiple episodes per day. A full workup by a neurologist, including an MRI, yielded no abnormal findings.
After examining Annie and consulting with her owners, we decided to try CBD-rich cannabis oil. We discussed the exact product and dosing that would be the safest and most effective for her.
Within two weeks, Annie's seizures were reduced by 75 percent. Her quality of life was significantly improved and her owners were thrilled. With a little fine-tuning of her dosing, we were able to further improve her seizure frequency. Although she still has the occasional seizure, Annie's life (and that of her owners) has been greatly changed for the better.
ANIMALS AND THE ENDOCANNABINOID SYSTEM
From an evolutionary perspective, the endocannabinoid system is quite old. All higher forms of animals have an endocannabinoid system, and it is even found in many primitive forms of life such as slugs. Just as in humans, the complex web of neurotransmitters in the endocannabinoid system is involved in physiological processes such as appetite, pain sensation, mood, and memory. While the overall function of the endocannabinoid system is similar in all animals, there are differences between species.
Dogs are particularly unique with regard to the endocannabinoid system because they have a greater concentration of endocannabinoid receptors in their brainstem and cerebellum than any other species does. These structures within the brain control heart rate, breathing, and muscle coordination. The dramatic response seen when dogs ingest excessive levels of cannabis containing THC is due to the high concentration of cannabinoid receptors as well as their relatively smaller size.
When dogs ingest excessive levels of cannabis containing THC, they lose muscle coordination, have difficulty with balance, and may lose bowel and bladder control. They will stand in a “sawhorse” stance and sway back and forth. This response is known as static ataxia and is unique to dogs. Depending on the size of the dog and the dose ingested, signs of toxicity can last from hours to days and may result in the dog being unable to eat or drink.
Conversely, cats react to overdoses of THC much the same as humans, although their small size frequently means the effects are severe and prolonged. While rarely fatal, some pets may require medical care to maintain their hydration during the time they are incapacitated. The few fatalities that have occurred in pets due to cannabis ingestion usually involve other toxic foods such as chocolate or coffee.
CAUTIONS ON THE USE OF CANNABIS TO TREAT PETS
Dogs have a higher number of endocannabinoid receptors in their cerebellum and brainstem than humans do. These parts of the brain control coordination, heart rate, respiratory rate, and more. This makes dogs particularly susceptible to toxicity from too much THC. Dogs intoxicated with THC may show signs of static ataxia. These dogs will seem rigid and have difficulty standing. This condition is unique to the dog and, while not fatal, often requires supportive medical therapy. Cannabis in any form is a highly pharmacologically active drug. Always consult with your veterinarian before administering any cannabis product to your pet. Because of the extreme sensitivity of small animals to THC, high-CBD products with little or no THC are frequently favored due to their greater margin of safety.
Oral Administration Cannabis oil, which is usually diluted in a carrier such as olive oil or coconut oil, is one of the simplest ways to administer the medicine to pets. It can be added to food or given directly by mouth. Preparations of a highly concentrated extract (CO2 or alcohol extraction are the cleanest methods) are diluted in the carrier to make appropriate dosing possible. Without dilution, the concentrated extracts (especially those containing THC) are difficult to dose with accuracy in small animals. Using undiluted concentrates greatly increases the chance of accidental overdose.
In addition to oils, cannabis-infused treats are available for pets. Most of these are CBD treats made from hemp and are sold over the counter nationwide. Hemp-based CBD treats have little to no THC, are very safe, and are often effective for mild to moderate aches and pains. Most practitioners agree, however, that, when higher doses are needed, hemp-based CBD treats and supplements are not as potent as those made from marijuana.
TOPICAL USE CANNABIS
Oils, salves, or sprays can be used on pets with skin allergies or even for arthritis and back pain. The cannabinoid receptors in the skin and hair follicles provide both surface (skin) and deeper (muscle and joint) relief. Many of these animals otherwise require steroids or other medications that may have harmful side effects. The effects of topicals in some patients are nothing short of amazing. Topicals are a great option for pets, although sometimes fur may need to be shaved and it is important to prevent the pet from licking off the medicine.
SMOKING AND VAPING
Under no circumstances should any attempt be made to dose a pet with cannabis by blowing smoke or vapor into its face. Pets have highly sensitive respiratory systems that are not equipped for this type of delivery. In addition, it is currently impossible to accurately dose medicine for pets this way. There may come a time when accurate dosing is available through a metered dose inhaler, such as is used with pets and people to administer asthma medication. Until then, stick to oral and/or topical administration only.
CHOOSING A CANNABIS PRODUCT FOR YOUR PET
With the advent of CBD products and effective low-dose THC therapy, cannabis products are becoming more common for treating animals safely and effectively. “The results are almost immediate," says Darlene Arden, a certified animal behavior consultant. “Elderly dogs are running around like puppies, and their last months or years are far more comfortable. Those with cancer are no longer in any sort of pain. It increases the appetite. In other words it improves the quality of life. Not surprisingly, few veterinarians are prescribing medical marijuana yet, but I think we'll see a trend that way once some testing is done.”
"Marijuana should be dispensed under medical care," Arden continued. "I think the benefits far outweigh any negative connotations, if it's used judiciously, people are educated about how to use and store it, and it is carefully dosed to the size of the dog.
There may have been a day when CBD was “riding the coattails” of THC when it came to how people viewed cannabis as medicine, but no more. CBD has become a major player in its own right. THC and CBD are both highly active compounds that overlap in their pharmacological use. However, while both can be effectively used for pain, inflammation, and treatment of cancer, CBD has particular affinities for treating conditions such as gastrointestinal disease and seizures. The primary goal when using cannabis as medicine in pets (and people) is determining which compounds can be used most safely and effectively.
Like all botanical medicines, cannabis is made up of many active compounds. It is theorized that there is a synergistic effect between these chemicals that ultimately is greater than the sum of its parts. This phenomenon, known as the “entourage effect”, is one of many reasons utilizing a whole plant as medicine is often better than attempting to isolate a single compound for pharmaceutical use. In the future, the full spectrum of cannabinoids, terpenes, and flavonoids within cannabis will be utilized to achieve the greatest medical effect. For now, however, product selection is most commonly based on the ratio of CBD to THC.
The relative ratio of CBD to THC is as important to successful treatment as is the actual amount of each compound present in a medication. THC and CBD each mimic a different neurotransmitter in the endocannabinoid system and thus have different effects on the body. The individual amounts of THC and CBD in a formula create a medicine that affects the body relative to the specific ratio used. For example, a formula that is well suited to fight cancer often will have a higher THC content, whereas one designed for seizures will have a higher CBD content. Since formulas can be created with specific ratios, it is possible to create medicines to help a wide variety of conditions.
When choosing a cannabis product for use in pets, it is imperative to know both the concentration of the medicine and the ratio of CBD to THC. The table below is a guide to product selection for specific diseases or conditions and the most appropriate CBD-to-THC ratio.
HIGH CBD, LOW THC (between 4:1 to 30:1)
DISEASE OR CONDITION Epilepsy/seizures Pain, inflammation Cancer Stroke or head injury Anxiety, restlessness (as an aid for pets who are not sleeping well) Inflammatory bowel disease Pain, inflammation Cancer, especially involving tumors Spinal cord injuries
EQUAL CBD and THC (1:1)
LOW CBD, high THC (between 1:4 to 1:20)
Severe pain such as advanced arthritis or cancer pain Appetite stimulation Cancer, especially involving tumors
For many conditions and in smaller pets, it is beneficial to begin with a lower-THC, higher-CBD medicine. This allows for a greater margin of safety and, if needed, acclimation to THC, which helps limit the chances of toxicity. Depending on the pet's response to the initial product, changes to higher THC doses can be made under veterinary supervision.
We had a thirteen-year-old golden retriever who developed a growth on his lip. It was removed and diagnosed as an oral melanoma. His vet told us that in all cases it would return, and at this stage of the cancer, these tumors would have metastasized to various other parts of the mouth, jawbone, and internal organs. Life expectancy was given as three weeks to three months with no treatment. The veterinary options were to cut back to the bone on the jaw line, along with standard cancer treatments of chemo and radiation, without any indication of extending life expectancy. When we asked about survival rates and any alternatives, we were told: “under the law of the land its the only thing we can offer!"
After researching alternatives, we settled on a mixture of medical hemp CBD and medical cannabis oil, mixed as 1:1, complemented with 1/4 teaspoon of baking soda in his food (to alkalize the body) on a daily basis, plus we changed his food to The Honest Kitchen. After six weeks, we returned to the vet and had a full examination, x-rays, and other “cancer” determining tests. The vet later returned with a look of seeing a ghost. “There's nothing there, absolutely nothing, its completely gone, not even the growth on the lip has reappeared.” Now six months later, our golden continues to be fit and healthy, and we continue with a maintenance regimen of a lower dosage of the CBD and medical cannabis oil, mixed as 1:1.
ACCURACY IN LABELING
Like any drug, the most important consideration with cannabis is to know exactly how much active ingredients are in the medication. With conventional pharmaceuticals, this is easy because standardized labeling allows us to know exactly what is contained within every liquid, pill, and capsule on the market.
Because our friends at the FDA have stated that cannabis has no legitimate medical use, they do not regulate or oversee product manufacturing or labeling. The upside of this is the presence of a lot of “boutique” companies making artisan products much like fine wine. A lot of love goes into these labeling. A cannabis preparation needs to be labeled with both the amount of CBD and THC in a given quantity, such as milligrams per milliliter (mg/ ml), and the ratio of CBD to THC. We must have both pieces of information for safe and successful medical use.
Many cannabis products do not contain enough information on their labels to be safe to give to pets. Additionally, in this “let the buyer beware” environment, some product labels contain inaccurate information that may lead to the medicine being ineffective or even potentially dangerous.
CBD FROM CANNABIS VERSUS HEMP
Although never fatal, concerns for THC-related toxicity in pets is a real thing. It may arise from a dosing miscalculation or through using a mislabeled medicine. Either way, the result is a stressful (and potentially expensive) situation for both pets and their owners. By comparison, the relatively wide margin of safety of high-CBD products coupled with their efficacy makes a compelling case for the use of CBD in pets.
Medical cannabis containing CBD comes from either marijuana or hemp. They are both essentially the same plant, although, legally, hemp contains less than 0.3 percent THC. So, does it matter where the CBD comes from?
The answer is both yes and no. Many people who use CBD as medicine report that marijuana products are more effective than hemp. The reason is most likely due to the entourage effect, in which a full spectrum of cannabinoids used in therapy seems to have a synergetic effect and work better. Recall that marijuana contains much more than just THC and CBD. A variety of other cannabinoids, terpenes, and flavonoids make up the whole plant. It is very likely that complex interaction between these phytochemicals leads to their medical efficacy. While hemp contains some of these compounds, higher levels are found in medical-grade cannabis.
The CBD in hemp is the same CBD found in cannabis. That said, the specifics of the plant of origin and the methods of manufacture are critical to efficacy and safety. Historically, CBD from hemp comes from “industrial” sources where focus on plant genetics is on fiber production rather than cannabinoid, terpene, and flavonoid content. These products are also some residues behind. Today, however, there are hemp producers growing plants specifically for CBD and using safe methods such as CO2 extraction to produce higher-quality medicine.
Regarding the use of CBD made from hemp, veterinarian Matthew J. Cote said, “What we've seen is that some of these dogs respond very rapidly. One woman from Fort Bragg was ready to put down her dog due to how sick and in pain he was, but the day before he was scheduled to go under, she administered our [CBD] treats and just like that the dog was up, walking around and acting normally again. "
GUIDELINES FOR PRODUCT SELECTION
CBD products made from hemp can be safe and effective, provided they come from high-quality plants and are manufactured safely, but this can be a challenge (see p. 203 for more on hemp vs. medical cannabis-grade products). It's a good idea to research companies and manufacturing methods thoroughly before purchasing. Complete and accurate labeling of medical cannabis is critical for safety and success with medicine containing THC. Product labels should contain both the concentration of CBD and THC (usually expressed in milligrams) as well as the ratio of CBD to THC. Always begin at a low dose and slowly work up as needed (see dosing information in the next section). This process will limit the chances of adverse reactions.
Think of cannabis as a prescription-strength medication. Use it with appropriate caution and always consult your veterinarian at every step of the way.
SAFE AND EFFECTIVE DOSING
We know cannabis is a complex combination of various forms of THC, CBD, terpenes, and flavonoids. It is, however, impractical to calculate the concentration of all of the compounds present in a given plant as a means of determining dosage. Since THC and CBD are the most biologically active cannabinoids, medical cannabis dosing is based on these two components.
When determining the dosing of cannabis for pets, the primary necessity is accurate labeling. Without this information, carefully calculated doses mean nothing. Assuming the product being used is labeled accurately, the other consideration to take into account is the biphasic dosing curve.
Biphasic Dosing Curve
Cannabis displays a phenomenon called a biphasic dosing curve; in short, it refers to the optimal dose for a given condition and individual. There is effectively a “sweet spot" with cannabis where it works optimally.
Given that there is no way to know exactly what the ideal dose is for any individual, the best strategy is to begin with a low dose and slowly increase on a weekly basis until the optimal response is found. Decreased efficacy from exceeding the optimal dose is different from overdosing in the sense of toxicity.
When purchasing a product specifically designed for pets, determining a dose should be easy: simply follow the directions on the label. But, even with CBD, and as stated previously, it is still advisable to start at the low end of the dosing range provided and slowly increase over time. This will prevent excessive sedation, which can occur even with CBD products.
Cannabis products produced for human consumption may have dosing information on them, but, once again, dogs and cats are not “small humans.” Dosing them as such may result in a trip to the emergency room.
The following dosage guidelines for dogs and cats have been derived from a combination of research data and veterinary experience. Recommendations vary by individual and condition, so always consult an experienced veterinarian prior to giving cannabis to your pet.
- Dose: 0.1-0.25 mg/kg/day
- Calculated dose should be divided for twice-daily dosing
- Start low and slowly increase to develop tolerance and adjust for thebiphasic dosing curve
- Although the amount of CBD in a given medicine is important, THC is the compound in cannabis that has the potential for toxicity. Thus, THC is always the limiting factor for any product containing THC. In order to prevent toxicity and a trip to the emergency room, accurate dosing is critical. Consult your veterinarian to assist you with the dosing calculations.
- Dose: 0.1-0.5 mg/kg/day
- Calculated dose should be divided for twice-daily dosing
Doses up to 5 mg/kg/day have been reported for difficult seizure cases Start low and slowly increase to adjust for the biphasic dosing curve
THE FUTURE OF MEDICAL CANNABIS FOR PETS
By anyone's estimation, the future of medical cannabis is bright. More and more states are legalizing cannabis, and it is inevitable that the FDA will ultimately be forced to reschedule marijuana and admit it has medical benefits. No one knows what is going to happen when Big Pharma tries to monopolize the industry, but, regardless, medical cannabis is here to stay.
Hesitation on the part of veterinarians to discuss the benefits of CBD (and THC) for pets is mostly founded in a lack of familiarity of how it works and the legal landscape. All of this is changing, however. Veterinarians are becoming more educated on the topic and are increasingly enthusiastic about how we can improve quality and quantity of life with this incredible medicine.
Until rescheduling and the entry of the pharmaceutical industry into the world of medical cannabis happen, the movement will continue to be a grassroots effort. Both veterinarians and pet owners are part of this process. The more cannabis is discussed and results shared with other pet owners and medical professionals, the greater the response will be within the veterinary community.