The Answers You Need
CAN VETERINARIANS LEGALLY PRESCRIBE MEDICAL CANNABIS IN CANADA?
No. Under current Canadian legislation, the only legal way to access medical cannabis is through the Access to Cannabis for Medical Purposes Regulation (ACMPR) which applies only to 'persons' and can be authorized only by physicians and nurse practitioners. Non-medical (aka "recreational") cannabis products are now also legally available through provincially licensed cannabis retailers under the new Cannabis Act, but are intended for human consumption and use in animals is considered similar to 'extra-label' drug use.
A prescription medication containing cannabis, Sativex (a THC/CBD oral spray), is available in Canada. As a drug licensed for human use, veterinarians could prescribe this medication in an extra-label manner, however, it is rarely the best choice for most veterinary patients.
CAN VETERINARIANS DISPENSE CBD PRODUCTS PRODUCED FROM HEMP?
No. Under the current legislation, CBD from any source that is sold outside of the two pathways described above is considered a prescription drug, and therefore requires drug approval from Health Canada and must contain a DIN number. We currently have no 'drugs containing cannabis' approved for animal use.
WHAT CONDITIONS COULD CANNABIS BE HELPFUL IN TREATING?
In human medicine, cannabis and its derivatives have been reported by patients to be helpful in treating a wide range of conditions, many of which we anticipate may respond similarly in veterinary patients.
Below is a list of just some of the many conditions that Health Canada lists as potential therapeutic uses:
Nausea and vomiting
Spinal cord injury
Headaches and Migraines
Arthritis and Musculoskeletal Disorders
Opioid and alcohol withdrawal symptoms
Alzheimer's and Dementia
Inflammatory skin diseases
Irritable bowel syndrome
Inflammatory bowel disease (Crohn's, colitis)
Type II diabetes
The strongest scientific support for cannabis use includes chronic pain and neuropathic pain, nausea (particularly chemo-induced), Dravet epilepsy, sleep quality, and symptoms of muscular sclerosis. In veterinary medicine, the strongest scientific support is in the use of CBD-dominant cannabis products in the treatment of chronic pain in dogs caused by osteoarthritis. Other studies have shown promise in tthe use of similar products in the treatment of canine seizures, canine anxiety, and dermatological diseases such as canine atopy.
HOW CAN ONE PLANT POSSIBLY HELP SO MANY SEEMINGLY, UNRELATED CONDITIONS?
Cannabis affects the mammalian body through numerous pathways, including those found within the Endocannabinoid System (ECS) and the broader Endocannabinoidome, which encompasses many receptors including the cannabinoid receptors.
The ECS is now thought to be the largest receptor system in the mammalian body and has been found throughout many parts of the body including both the Central and Peripheral Nervous Systems, the Endocrine System, the Gastrointestinal System, the Skin, the Cardiovascular System, Ocular structures, the Reproductive System, etc.
HOW CAN I LEARN MORE ABOUT THE ENDOCANNABINOID SYSTEM?
There are many excellent online resources for learning, including PubMed, Wikipedia, ProfOfPot.com, Leafly.com, ProjectCBD.org, LearnGreenFlower.com, or of course, through the CAVCM website!
ISN'T THC TOXIC FOR DOGS?
Dogs have long been reported to have a higher concentration of CB1 receptors in certain areas of the brain (particularly the brain stem and cerebellum) than people. Newer studies that have examined the distribution of CB1 receptors in the canine brain, however, have not supported the theory that dogs have 'more receptors', but rather a greater concentration of CB1 receptors in the cerebellum, the area of tthe brain that controls balance. This no doubt explains the unique 'sensitivity' that dogs appear to experience upon naive exposure to THC. As with many medications, it is important to recognize that “the poison is in the dose”, and new studies are looking at the potential therapeutic benefits of using THC in animals, including dogs. Previous studies have shown that the minimum dose typically required to produce signs of toxicity in dogs, is 0.5mg/kg administered intravenously, however, differences in routes of administration, individual variances, and adaptation, can make knowing the exact dose to avoid difficult.
WHAT ARE THE COMMON SIGNS OF THC OVER-CONSUMPTION/INTOXICATION?
THC toxicity is commonly associated with ataxia, lethargy (or sometimes agitation), disorientation, dilated pupils, urinary incontinence, hyperesthesia, and less frequently, tremors/seizures and vomiting. Changes in vital signs including a low heart rate, low body temperature, and low blood pressure can also be seen. In severe cases, patients may present comatose.
Although urinary incontinence, in combination with the more common signs, has often been used as a diagnostic tool for THC toxicity, a paper published in the Journal of Veterinary Emergency and Critical Care 2012 reported only 47% of THC toxicity cases actually present with urinary incontinence, so veterinarians need to be aware that the lack of incontinence should never rule out THC toxicity as a possible differential diagnosis.
HOW IS THC INTOXICATION TREATED?
The treatment of THC toxicity will vary depending on the severity of presenting signs, and/or the known type, amount, and concentration of product ingested.
Treatment is typically focused on supportive care and reducing further absorption/increasing clearance of THC from the body.
Symptoms can be seen within 30 minutes of ingestion and can persist up to 72 hours.
In an attempt to prevent further absorption, inducing emesis and activated charcoal may be used, although its usefulness has been questioned, and should be avoided if the patient is at risk of aspiration.
For mild cases, monitoring and supportive care including maintaining normal body temperature, keeping quiet, and maintaining hydration may be all that is required.
For those patients requiring hospitalization, supportive care, close monitoring of vital signs, maintaining normal blood pressure and hydration with IV fluids, and rotating body position every 4 hours is recommended, +/- in combination with intravenous Intralipid.
For severe cases, the use of intravenous Intralipid 20% could be considered to further limit absorption. This product can be administered intravenously as an initial bolus over 1 minute, then as a CRI at 0.25ml/kg/min x 30 minutes. This treatment can be repeated q4-6hrs PRN. As a lipophilic molecule, THC will bind with Intralipid and allow removal from the body in a more rapid manner.
Seizures/tremors can be treated with benzodiazepams, but may add to CNS depression.
FOR PET FAMILIES WHO CHOOSE TO USE CANNABIS/HEMP FOR THEIR PETS, WHAT ARE THE SAFEST WAYS TO ADMINISTER PRODUCTS?
Pet owners have been using cannabis and cannabis-derived products for several years, through a range of techniques. Some are relatively safe, and others carry a high risk of accidental toxicity. The most commonly used method is through the use of liquid oils or tinctures that allow for gradual titration of the dose. Other methods include the use of capsules, edible pet treats (NOT human treats that may contain other toxins such as chocolate, xylitol, or raisins), topicals, and transdermals. Whichever way a person chooses to treat their pet, they should always discuss their decision with their veterinarian.
Obviously, treatments involving smoke should be avoided, as the smoke is irritating to most pets (not to mention the difficulty of getting most pets to participate willingly).
The use of concentrates, while potentially beneficial, also carries a greater risk of toxicity given the difficulty of controlling the dosage, and the frequent lack of knowledge as to the exact content. Home-prepared and illicit concentrates may also contain unwanted, and potentially dangerous residues, depending on the extraction technique utilized.
Edibles which contain other toxins (such as chocolate and raisins) should be avoided. These products can also have very high levels of THC, and increase the risk of toxicities.
For those edible/treat products made specifically for pets, the biggest concern is the consistency of active ingredient from treat to treat (ie. Was the medication properly dispersed throughout the batch), and whether the heating process caused combustion of some of the cannabinoids, thereby reducing the efficacy.
The use of dried and fresh plant material is generally considered relatively safe, as, without heating (which causes decarboxylation), both THC and CBD remain predominately in their acid-forms of THC-A and CBD-A. These cannabinoids are not psychoactive and do not cause toxicity. However, their medicinal effects vary from their decarboxylated forms, THC and CBD respectively.
WHAT DOSE SHOULD PET OWNERS USE, IF THEY CHOOSE TO USE CANNABIS FOR THEIR PETS?
Currently, we have limited evidence-based studies that have been published stating a recommended dose for either CBD or THC dosing. This is what we do know:
CBD has been used anecdotally for many years at doses typically ranging from 0.1-0.5mg/kg once or twice daily. In multiple published studies with dogs, the CBD dose used was 1-2.5mg/kg twice daily and appeared generally well tolerated.
THC is a little trickier as we currently have no published data on dosing other than old research showing a dose of 0.5mg/kg THC given intravenously was required to show signs of intoxication. That said, there is a wide range of individual responses and sensitivities, so the golden rule of START LOW, GO SLOW definitely applies.
Particularly when using a product with THC, veterinary oversight is urged to ensure the safety of the animal.
ARE THERE CONTRAINDICATIONS OR POTENTIAL DRUG INTERACTIONS WHEN USING CBD? (OR THC?)
Based on anecdotal reports, and studies done to date, it appears that CBD is well tolerated, even at dosages much higher than those commonly used, however, drug interactions are possible and all cannabis use in animals (including CBD) should be discussed with a veterinarian.
Potential interactions can be seen due to shared modes of action, and cumulative sedation. However, the most frequently discussed interactions revolve around the use of Cytochrome P450 enzymes to metabolize both THC and CBD, which are shared by many other medications.
Studies examining the effect of CBD administration on human blood levels of various anticonvulsants have shown significant effects, so close serum monitoring is recommended, when possible, for patients receiving polypharmacy.
Relative contraindications may include severe heart disease, liver disease, pregnancy and/or lactation, stud use, and use in immature animals.