– In July 2021 we have 2 scientific studies done on cats.
– These studies are both funded by companies that manufacture CBD products.
– In only one of them results are compared with placebo (the other is very simple).
– These studies explore the safety profile, there are no published studies that prove any kind of benefits at this moment.
– The number of cats examined was very small, 20 in the first study, 8 in the second.
– There were no major safety issues found yet, though your cat may experience licking, head shaking, vomiting, drooling and a few more adverse effects.

Here are more details about both of the existing studies done on CBD for cats:

1) The first question: is CBD safe for cats and to they tolerate CBD well? To answer it we take a look over the first feline study to explore the safety and tolerability of CBD in a controlled research setting. The study was named Safety and tolerability of escalating cannabinoid doses in healthy cats and it was done recently in March 2021 in
Journal of Feline Medicine and Surgery https://journals.sagepub.com/doi/10.1177/1098612X211004215) . This was a placebo-controlled, blinded study, done on 20 healthy adult cats who were randomized in 5 treatment groups. Two groups got the placebo (sunflower oil) and the other 3 received CBD orally in up to 11 escalating doses, with 3 days delay between doses. Then safety and tolerability were determined from clinical observations and complete blood counts.

Conclusions were these:

– all observed adverse events (AEs) were mild, transient and resolved without medical intervention.
– even though the article you are reading covers mainly implications for CBD in cats, you should know that this paper covered THC as well, and that the THC containing oils led to more frequent adverse effects and behavioral changes.

Noteworthy things about this study:

– Canopy Animal Health, a division of Canopy Growth Corporation, financially supported this research. They produce a line of CBD products for pets. Some of the researchers are employed (or were previously employed) by this corporation.
– There were no conditions attached to the allocation of funds for this study.
– Staff at VivoCore (which is part of the Scientific Research & Development Services Industry) were overseeing the study procedures
– Vivienne Marshall PhD (Director of Clinical and Research Operations at South Texas Blood & Tissue Center – https://www.linkedin.com/in/vivienne-marshall-phd-bba43714) reviewed and provided feedback on the manuscript.

2) Single-Dose Pharmacokinetics and Preliminary Safety Assessment with Use of CBD-Rich Hemp Nutraceutical in Healthy Dogs and Cats

This second study is an older study published in October 2019 and it was smaller in size (8 cats). It was published in a special issue of Nutraceuticals and Animal Physiology: Performance and Welfare . The purpose of this study was to provide a preliminary assessment of safety and adverse effects during 12-week administration using a hemp-based product in healthy dogs and cats. For the purpose of this article we will cover only relevant details about cats and CBD. For more research about the effects of CBD on dogs please check out our detailed article. In this study 8 cats with a mean age of 4.5 years received 2 mg/kg total CBD concentration orally twice daily for 12 weeks. Cats were observed for signs of adverse events twice a day for the 12-week study for a total of 1344 observation periods.

Results:

– Two cats were observed to salivate heavily after administration and the study staff was not confident that two of the participants received the entire dose due to capsule rupture and were dropped from the pharmacokinetic study portion.
– The main adverse effects noted included licking and head shaking, which were observed 476 (35.4%) and 339 (25.2%) times, respectively.
– Other adverse events noted were pacing , chomping/chewing, gagging, vomiting food, bile, or hairballs, salivating, drooling, or foaming. For more information on the frequency and to see other adverse effects not mentioned here check the 3.3 section of the study.
– Loose stool was not observed in any of the cats during the study.
– Food consumption and body weight of the cats remained consistent during the 12 weeks.
– Cats do appear to absorb or eliminate CBD differently than dogs, showing lower serum concentrations and adverse effects of excessive licking and head-shaking during oil administration.

Noteworthy things about this study:

– this study was supported from a grant from Ellevet Sciences which is a manufacturer of CBD products for cats and dogs.
– it was simple in design, there was no comparison of results against placebo, and consequently it was not blinded (where the researchers don’t know which dogs get CBD and which get placebo)
– the number of cats was small, only 8, among which 2 were excluded because the study staff was not confident that two of the participants received the entire dose

Besides these two studies there is another narrative review of the current literature titled Feline cognitive dysfunction as a model for Alzheimer’s disease in the research of CBD as a potential treatment — a narrative review, that has been published this journal (https://jcannabisresearch.biomedcentral.com/). It’s important to know that this is not an actual research paper / study, it’s just a narrative review of what was known about CBD, cats, Alzheimer’s disease and Feline cognitive dysfunction and in December 2020.

The important things mentioned in this paper concerning cats and CBD are:

– There is a shortage of literature regarding the usage of CBD in domestic cat
– The owned cat population is aging thanks to improved nutrition and medical veterinary care.
– The aging cat population displays behavioral changes which can be attributed to cognitive dysfunction.
– Feline cognitive dysfunction is a disorder in cats which causes a decline in the aging cat’s cognitive abilities, without any known underlying medical reason
– Several animal models have shown cannabidiol (CBD) has potential to treat and reverse the changes seen in the brain in AD, although further research to support this is necessary
– Alzheimer’s disease and feline cognitive dysfunction severely impair the patient’s health and quality of life and impose a significant burden on their caretakers.
– Older cats and especially cats suffering from cognitive dysfunction do not tolerate either handling, or medication or hospitalization well (due to the stress involved). Exploring treatments that can be administered in their food would be beneficial.

Besides acknowledging that there is not enough research for CBD and cats, the reviewers suggest that clinical trials researching the benefits of CBD in aging domestic cats have the potential to identify treatments and to work as a promising model for human Alzheimer’s disease.

1) US Veterinarians’ Knowledge, Experience, and Perception Regarding the Use of Cannabidiol for Canine Medical Conditions

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6338022/pdf/fvets-05-00338.pdf

If you are interested to see what the science says about CBD and dogs, among of the first things we should look at is the current knowledge level, views and experiences of veterinarians. They should be among the most knowledgeable and up to date on this topic. Even if few particular veterinarians might not be up to date on this subject, if we look at a larger scale, things should even out and some clear patterns may emerge. This first study was published in January 2019, so, it’s a bit old, and it was published in the journal Frontiers in Veterinary Science  . In it there were 2130 were surveyed online to unveil information about their knowledge level, views and experiences related to the use of cannabinoids. Only veterinarians who stated that they treat dogs in their clinical practice participated in the survey. This was an anonymous survey conducted in collaboration with VIN – Veterinary Information Network – which is an online veterinary community. The survey was created and tested for usability by researchers at Colorado State University, and it was sent by email to all 34.000 VIN members. The authors declared that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Here are some of the most important findings:

-> Most veterinarians (61.5%) felt comfortable discussing the use of CBD with their colleagues.
-> 45.5% veterinarians felt comfortable discussing the use of CBD with their clients.
-> Recent veterinary graduates were less likely to recommend or prescribe CBD.
-> The most commonly used CBD formulations were oil/extract and edibles. These were most helpful in providing analgesia for chronic and acute pain, relieving anxiety and decreasing seizure frequency/severity.
-> The most commonly reported side-effect was sedation.
-> Participants felt their state veterinary associations and veterinary boards did not provide sufficient guidance for them to practice within applicable laws.

There are other findings related to legality and other more useful for veterinarians than dog owners, if you are curious, you should take a look for yourself. This type of study is easier to digest than the other which are more abstract.

So, we learned a few things from this study, first, that a big part of veterinarians felt comfortable discussing CBD with their clients, and that the most commonly reported side-effect was sedation. At least we know that we don’t have other major / serious issues happening frequently. The good news that there are some studies that evaluate the safety, so let’s cover them next.

2) Report of adverse effects associated with the administration of cannabidiol in healthy dogs

https://downloads.tripawds.com/files/2020/01/AHVMA-2018-V52-CannabisAdverseEffects.pdf

This was one of the first studies that analyzed the safety and side effects of CBD in dogs. It was first published in fall issue of 2018, volume 52 of the Journal of the American Holistic Vererinary Medical Association (JAHVMA). A group of 30 healthy Beagle dogs were randomly assigned to receive CBD in the form of capsules, CBD-infused oil, or CBD-infused transdermal cream at a dose of 10 mg/kg/day or 20 mg/kg/day for 6 weeks. And they tried to record any short-term effects. This is what they found:

Overall, the product was well tolerated clinically. However, clinically signicant adverse effects, particularly diarrhea and elevations in serum ALP levels, are noteworthy and warrant further discussion and research.

• throughout the 6-week study period, gastrointestinal upset was the most frequently recorded adverse clinical sign
• all of the dogs in the study developed diarrhea
• 20% of the dogs had single episodes of vomiting
• the dogs that vomited were in the groups that received CBD orally in the form of capsules or oil
• there was no correlation between the episodes of vomiting and the dose or formulation of CBD
• the episodes of diarrhea were suspected to be secondary to the CBD treatments, but dietary variation, including treats, and stress from being housed in a new facility could not be ruled out as contributing factors

Each dog’s weight was evaluated weekly and remained stable for the duration of the study. There were other minor adverse effects, if you are concerned you should take a loof yourself.

Other noteworthy things about this study are:

• it was simple in design, there was no comparison of results against placebo, and consequently it was not blinded (where the researchers don’t know which dogs get CBD and which get placebo)
• the study was funded by Applied Basic Science Corporation which is a CBD product manufacturer

Fortunately, there is a newer study in similar scope which was placebo-controlled. Let’s cover it next:

3) Randomized, placebo-controlled, 28-day safety and pharmacokinetics evaluation of repeated oral cannabidiol administration in healthy dogs

https://avmajournals.avma.org/doi/full/10.2460/ajvr.82.5.405

The objective of this next study which was published in American Journal of Veterinary Research quite recently (May 2021), was to determine the safety of repeated oral administration of plant-derived CBD purified (> 95% CBD wt/wt, corrected for moisture) compared to placebo.The research was done on 20 healthy adult Beagles, so the sample size was very small. However, beside the small sample size, the rest of the characteristics of this study were pretty good. It was a a randomized, blinded, placebo-controlled trial in which the CBD was administered daily over a period of 28 days. The dogs were examined daily for possible outcomes, and blood samples were collected at different time points. The dogs were split in 5 groups based on body weight and sex, and received CBD in various dosages – 1, 2, 4, or 12 mg/kg.

The outcome was straightforward: repeated CBD administration was well tolerated by dogs, with no clinically important changes in measured safety outcomes. There were some mild adverse effects relative to placebo administration at high dosages, mainly hypersalivation and higher serum alkaline phosphatase activity. So if you decide on trying it, it would be advisable to work with lower dosages.

Other noteworthy things about this study are:

• it was funded by a division of Canopy Growth Corporation, which is a company engages in the production, distribution, and sale of CBD!
• there were no conditions were attached to the allocation of funds for this study.

So, we should take this with a grain of salt, at least until we have more studies which confirm the same findings, especially independent studies.

4) Single-Dose Pharmacokinetics and Preliminary Safety Assessment with Use of CBD-Rich Hemp Nutraceutical in Healthy Dogs and Cats

https://www.mdpi.com/2076-2615/9/10/832/htm

This study was published in October 2019 in a special issue of Nutraceuticals and Animal Physiology: Performance and Welfare and had the purpose to provide a preliminary assessment of safety and adverse effects during 12-week administration of a CBD product in healthy dogs and cats. 8 dogs and 8 cats received 2mg/kg total CBD concentration orally twice daily (every 12 h) for 12 weeks. The 8 healthy Beagle dogs had a mean age of 3.2 years (ranging from 11 months to 5 years.  They received ElleVet Mobility Chews twice daily for 84 days. The dogs were monitored prior to the start of the study and then every 4 weeks. The cats were a bit older with a mean age of 4.5 years, and they received CBD-infused fish oil. One dog did not consume the entire dose from the start and it was dropped from the study. The dogs and cats were observed for signs of adverse events twice a day for the 12-week study. Here is what they found:

• For the duration of the study there was a high rate of acceptance of the CBD-infused chews, with an average acceptance rate of 96.7%. Five of the eight dogs had a 100% acceptance rate, on rare occasion 3 of the 8 dogs required manual treatment administration.
• Out of 1344 total observation periods, 53 adverse events were reported.
• Loose stool was the most common adverse event noted among the eight dogs and occurred 44 times
• Vomiting was recorded as either food or bile emesis. Vomiting was only recorded 6 times (0.45% of the time).
• Food consumption and body weight remained consistent during the 12 weeks.
• Physical examinations revealed no abnormalities or changes in behavior in the dogs throughout the study.

For cats the main adverse effects noted included licking and head shaking, which were observed 476 (35.4%) and 339 (25.2%) times, respectively. Other adverse effects noted were pacing, gaging, vomiting, salivating and a few more, for more info check the 3.3 section of the study.

Other noteworthy things about this study are:

• it was simple in design, there was no comparison of results against placebo, and consequently it was not blinded (where the researchers don’t know which dogs get CBD and which get placebo)
• it was funded Ellevet Sciences, the company that produced the treats used in the study

Results should be interpreted with caution, especially until we have more with similar findings.