Cannabinoid Oil for Pets – Is it Safe and Effective?

Cannabinoid Oils for Pets

We often hear the terms CBD, THC, Cannabis and Hemp and we think of marijuana use. Marijuana is an illicit drug in many parts of the United States and Europe and only recently became legal in Canada. However, CBD and THC, chemical compounds found in marijuana, are used medicinally by humans to alleviate symptoms associated with epilepsy, pain, neurodegenerative diseases and cancer. Little is still known about the long term effects of marijuana use but studies have shown that it is not addictive like many narcotic pain killers and it does not cause toxicity like long term use of over the counter pain killers such as tylenol. Even less is known about the safety and efficacy of CBD and THC use in pets, however, dogs have played a role in drug studies that have been approved for use in humans. I had heard about the use of CBD oil for pain and epilepsy in pets. As a recent graduate, I was curious as to why it was never mentioned in lectures. I decided to research the topic myself.  Here is what I found… 

Cannabis Plant

What is Cannabinoid Oil?

Cannabis, or marijuana, is a psychoactive drug derived from cannabis plants. Cannabis plants contain compounds called cannabinoids, a group of more than 60 compounds. Examples of cannabinoids are Tetrahydrocannabindiol (THC) and Cannabindiol (CBD).  THC is the main cannabinoid found in marijuana plants. It causes the psychoactive effects that produce the “high” associated with recreational cannabis use. Hemp is a type of cannabis plant but it contains very little THC. CBD is the main cannabinoid found in Hemp and the second most active ingredient in marijuana. It does not cause a “high” like THC. 

Endocannabinoid Receptor System

Cannabinoids interact with the endocannabinoid receptor system in the body to control the amount of neurotransmitter (chemical messenger in the brain) released by a neuron (cell in the nervous system). This allows cannabinoids to control how neurons send, receive, and process a chemical signal. Cannabinoid receptors (CB1 and CB2) are widely distributed throughout the central and peripheral nervous system. When a person uses cannabis, the THC binds to the endocannabinoid receptors which prevents natural cannabinoids from binding to the receptor resulting in altered reaction time, memory, judgement and other cognitive impairments.  

Endocannabinoid Receptor System

The endocannabinoid receptor system is known to play a role in regulating pain and inflammation. Cannibis has been shown to control pain in cancer patients and people with arthritis. Research into the pain relief properties of Cannabis is quite new because it is a controlled illicit substance in many states. More research is needed to understand the effects of medicinal use cannabinoid oil in pets.

Below I have provided an overview of three recent cannabinoid oil studies that investigated the safety and efficacy of cannabindiol oil use in dogs and cats. 

Cannabinoid Oil - What is the Safest Dose?

A study was conducted to determine whether 3 cannabinoid oil formations were safe in dogs and the most tolerable dosage of each. 

The subjects of this study were 20 Beagle dogs that were placed in one of five randomized groups…

    • CBD-predominant oil
    • THC-predominant oil
    • CBD/THC-predominant oil
    • Medium-chain triglyceride (MTC) oil – placebo
    • Sunflower (SF) oil – placebo
beagle dog

The concentration of each oil was slowly increased over 10 doses based on the standard dosing technique for Cannabis research: start with a low dose and increase slowly. The results of this study showed that CBD oil had the least effect on food intake and physical activity compared to the other treatment groups.  One dog suffered severe ataxia (lack of muscle control and coordination) from the 7th dose of THC oil and was removed from the study.  Two dogs suffered severe ataxia and/or lethargy from the CBD/THC oil, therefore, all 4 dogs in this treatment group were removed from the study. No dogs experienced severe adverse reactions from CBD oil or placebo oil that resulted in removal from the study.

At least one adverse event was observed in all 20 dogs and included neurological, dermatological, ocular, and respiratory issues. CBD had the least amount of adverse events compared to the other treatment groups. Most adverse events were mild (479/505) and consisted of:

Mild Adverse Events

  • nausea
  • vomiting
  • diarrhea
  • lethargy
  • hyperesthesia (hypersensitivity to any of your senses)
  • muscle tremors
  • mild ataxia (lack of muscle control and poor coordination)
dog sitting on couch

Gastrointestinal adverse events were more common in placebo and CBD oil groups and neurological events were most common in THC and CBD/THC oil groups. Moderate adverse events (hypothermia, lethargy, ataxia) were not observed in the CBD oil group but were observed in the other groups. Hypothermia was the most common and usually resolved in 3 – 24 hours. No severe reactions with CBD oil were observed. CBD max dose of 640.5 mg was tolerated with minor adverse events that were similar to those observed in the placebo group (MTC).

Boston Terrier

Moderate Adverse Effects

  • hypothermia
  • moderate lethargy
  • moderate ataxia  (lack of muscle control and poor coordination)

In previous studies, CBD has been shown to be relatively well tolerated.  Some dogs in this study had slightly elevated liver enzymes (one dog in CBD group and one dog in  CBD/THC group), however, they were not elevated to a degree that was considered to be clinically significant by the vet. Elevated liver enzymes have also been observed in previous studies with dogs, humans and rodents. Effects of CBD/THC oil may be a result of CBD increasing the psychoactive effects of THC. It has been previously reported that CBD can interact with THC and increase the effects instead of reduce the effects of THC. CBD may be useful for pain management and seizure reduction. Short and long term effects of CBD need to be investigated in dogs.

Our findings provide support for continuing research on CBD's safety profile and potential therapeutic uses in dogs so that it may be considered a treatment option in veterinary medicine.

Vaughn, Kulpa and Paulionis, 2020

Cannabinoid oil- Pharmacokinetics and Safety

The purpose of the study was to determine the pharmacokinetics (the onset, duration and intensity of effect) and safety of CBD in dogs and cats. Six healthy Beagle dogs and cats were given 2mg/kg of CBD by mouth twice daily for 12 weeks. Dogs were dosed using ElleVet Mobility chews and cats were given CBD in fish oil.  Analysis of blood samples showed that the time it took to reach maximal concentration (amount of CBD in the blood) of the drug in dogs was 1.4 h and in cats 2h.

Food consumption and body weight of the dogs and cats remained consistent during the 12 weeks. Physical examinations revealed no abnormalities or changes in behavior in the dogs and cats throughout the study. All participants were evaluated twice daily for signs of adverse reactions.

Serum chemistry and CBC results showed no clinically significant issues. However, a single cat showed a consistent increase in a liver enzyme above the normal reference range during the trial.

pomeranian puppy

Observations of the dogs were recorded twice a day for the 12-week study. Adverse events were noted 53 times out of 1344 observations. Loose stool and vomiting were the main adverse events that were observed. Loose stool was the most common adverse event observed occurring 3.3% of the time. Vomiting occurred only 0.45% of the time.

Cats were also observed for adverse events twice daily for the 12-week study. The most common adverse effects noted included:

  • licking (35.4%) 
  • head shaking (25.2%)
  • pacing (11.1%)
  • chomping/chewing (6.5%)

The following adverse effects were also observed less than 2% of the time: gagging, vomiting (food, bile, or hairballs), salivating/drooling/foaming at the mouth, jumping, being uncooperative and grimacing. Interestingly, none of the cats had loose stool during the study.

Cats appear to absorb or eliminate CBD differently than dogs, showing lower serum concentrations and adverse events of excessive licking and head-shaking during oil administration.  

cat licking its paw

Cats had a lower maximal concentration (43 ng/mL) than dogs (301 ng/mL) which suggests that dosing may differ between the two species. This study reported a significantly lower half-life than previously reported (1h for dogs and 1.5h for cats).

The study demonstrates that a CBD supplement administered every 12 h is not harmful for healthy cats and dogs based on CBC and biochemistry values. However, more adverse events were noted in cats, therefore, more work is required to fully understand absorption and effects of CBD supplements in cats. There is still little information regarding dosing, best method of delivery and long term effects therefore further investigation is required.

Cannabinoid Oil - Does it Really Relieve Pain?

Osteoarthritis (OA) is a very painful condition resulting from the breakdown of cartilage between joints. OA most commonly affects older and larger dogs such as German Shepherds and Labrador Retrievers. Unfortunately, there is no cure for this condition but relieving the pain caused by OA is crucial. NSAIDs (anti-inflammatory pain killers) have been the go-to pain reliever for the condition, but they have been shown to cause adverse side effects especially in dogs with decreased liver and kidney function. The most common being gastro-intestinal issues. Veterinarians and pet owners have recently been interested in alternative therapeutics such as CBD oil. This study aimed to determine an effective and  safe dose of CBD oil that would alleviate the pain caused by OA.

An initial study with 4 beagle dogs determined that 2mg/kg was the appropriate dosage compared to 8mg/kg. Pharmacokinetics revealed an elimination half-life of 4.2 h at both doses which is higher than the study above. No observable side effects were noted. Maximal concentration range from 60.7 ng/mL to 132.0 ng/mL which was reached in 1.5h. 

Owner giving dog CBD oil

Sixteen client-owned dogs were included in the main study. Dogs received one of two treatments: CBD oil (2 mg/kg) or placebo oil every 12h. Each treatment lasted for 4 weeks with a 2-week period between treatments.  Hematology, serum chemistry and physical examinations were performed at each visit.

Veterinary assessment showed decreased pain and an increase in activity during CBD treatment. No side effects were reported by owners, however, serum chemistry showed an increase in a liver enzyme during CBD treatment.

This pharmacokinetic and clinical study suggests that 2 mg/kg of CBD twice daily can help increase comfort and activity in dogs with OA.

Labrador retriever sitting in the grass with owner

Recent medical interest in alternative therapies and modalities for pain relief has led many pet owners to seek hemp related products rich in cannabinoids.

Gamble et al., 2018

Final Thoughts

These three studies show that more work is required to determine the most effective and safe dose of CBD oil for dogs and cats. Overall, each study showed that CBD oil has only mild side effects in healthy dogs and provided pain relief to dogs suffering from OA. In addition, the pharmacokinetics seem to differ between cats and dogs with cats experiencing more adverse effects. There is little research regarding possible drug interactions, which is something to keep in mind when weighing the pros and cons of CBD use in pets taking other medications. Since more research is needed regarding the safety and efficacy of CBD supplements in pets, I would recommend talking with your veterinarian. They will provide you with their professional opinion on whether CBD use is beneficial and safe for your pet. 

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