Calming chews are all the rage these days. Dogs get anxious, whether it be because of lightning strikes, strangers, or simply being left alone. What if a supplement could teach an old dog new tricks and get them to calm down?
Looking into this question provides a fantastic example of why we can’t simply say, “there’s a study behind this, therefore it must work.” Studies have flaws, and bad studies can be propped up to sell you a product that will only separate you from your money.
“As above, so below,” goes the verse. Well, as with humans, so with pets. Bad science spares no living creature.
The appeal to nature
Calming chews aimed at dogs can contain any one (or many) of a long list of ingredients. There’s melatonin, the hormone many animals produce when it’s time to go to sleep, as well as cannabidiol (CBD), a molecule found in cannabis (including hemp) and which has been decorated withĚýan array of dubious health claims. But you will also find chamomile, passionflower, valerian root, gingko biloba, L-theanine, ashwagandha, casein, L-tryptophan,ĚýBifidobacterium longum,Ěýmagnesium, and many more. Basically, if it has been endorsed by the wellness industry as a remedy against human stress, you will see it in the ingredients list of canine chews.
Why are so many companies selling you calming chews? Because they can market them as “natural.” While there are drugs veterinarians can prescribe for canine anxiety (e.g. gabapentin and trazadone), some dog owners may be uncomfortable with the pharmaceutical route. But a calming chew is “natural,” right? Well, there’s nothing natural about cramming an herbal extract into a bone-shaped cookie, but the aura of naturalness is a powerful motivator for people. We want to believe that natural things are good for us and that synthetic products are harmful. But, as our Office has been reminding people for 26 years, it’s the dose that makes the poison, not the origin. Venom is natural but can kill you, and we can synthesize vitamins in the lab which are indistinguishable from their natural equivalents. Yet, “natural” sells.
Similarly, a product will look more appealing if it seems supported by science. A study shows the active ingredient in this calming chew works against canine anxiety, you say? That’s all many consumers need to be convinced to give the product a try.
But not all studies are created equal, and calming chews expose how easy it is for science to give a product a halo that it hasn’t earned.
Pet peeve
Here’s how the halo is created.
Scientists write about how some molecule in nature could conceivably help to fight anxiety by binding to this or that receptor, or by being part of a biological Rube Goldberg device where one molecule activates another, which inhibits another, until we end up deactivating part of the stress response. This looks promising, so a team of researchers uses it to justify a tiny study in ten dogs where 17 different variables are measured. Five of them move in the right direction, which gets plastered in the abstract for the paper they write, in which they conclude that this ingredient is very promising and that more studies are needed. People argue that it’s cheap, easy, and unlikely to cause harm, so it gets sold as a calming chewĚýas part of a whole behavioural training regimen to teach dogs how to deal with anxiety.ĚýAnd when their pet’s anxiety is indeed reduced, the dog owner, who paid for the chews, concludes that the supplement must work.
I want to be clear: no one in this chain of events needs to be lying. It’s a scientist’s job to find connections and propose hypotheses. Researchers do their best with the grant money they can scrounge up, and they are highly incentivized to extract positive results from a messy data set. Supplement companies are in the business of innovating and are likewise incentivized to use preliminary findings to sell you a product before their competitors jump on that same ingredient. And dog owners want their companions to calm down and generally don’t have the time or inclination to run trials with their pet to see if it’s the calming chew that’s working or the behavioural training regimen recommended by their vet, so they do both concurrently. This leads them into the arms of the caregiver placebo effect, where the dog owner thinksĚýthat the supplement worked when it didn’t.
The bottom line, though, is that I have found the research into the ingredients typically used in calming chews to be thoroughly unimpressive. Here is aĚýĚýof alpha-casozepine (Zylkene), a derivative of milk, sponsored by the supplement maker and comparing it to anti-anxiety medication… with no placebo group, no error bars on the graphs, and where dog owners were also instructed to use training to help their dog deal with anxiety.
Here is aĚýĚýdone in healthy dogs of a supplement containing polyphenols, prebiotics, and omega-3 fatty acids…Ěýwhere anxiety was not even assessed. Instead, the scientists measured molecules in the blood that have been linked to anxiety.
And here is aĚýĚýoften cited to support the use of a bacterium,ĚýBifidobacterium longum,Ěýto help with dog anxiety, but it’s a conference talk from a team working for NestlĂ© Purina Research, the R&D arm of a company that manufactures Calming Care Probiotic Supplement for Dogs.
Speaking of Purina, they have the money to do proper studies: NestlĂ©, their parent company, made roughly USD 100,000,000,000 inĚýĚý(that’s one hundred billion dollars… I had to look it up). They just don’t need to. Most consumers will buy anything so long as it’s labelled as natural, and many of the remaining skeptics will be swayed by allusions to studies and won’t scrutinize them.
Even aĚýĚýof the state of our knowledge on this issue—a review which isĚývery kindĚýto the quality of the evidence—concludes that these supplements should be used at the same time as a series of modifications to the pet’s environment and to their training. But if you do that, you have no idea if any improvement seen would have happened without the supplement.
I reached out to two trusted sources in this space to see if perhaps I was being a bit too cynical: an evidence-based veterinarian and an advanced veterinary nurse. Brennen Mackenzie runs theĚý, and in 2019 he wrote aboutĚýĚýhe was able to find for Purina’s Calming Care Probiotic for Anxiety in Dogs supplement, which is supposed to alter your dog’s gut bacteria to “support calm behaviour.” The best he found was that Purina-sponsored conference talk, which had not been published anywhere as a paper. A year before, he had examined the evidence for L-theanine, an amino acid found in green tea and marketed under the name Anxitane, to help alleviate canine anxiety, and concluded thatĚý
In his email to me, Mackenzie warns that it’s difficult to give a deep evaluation of everything that’s available in the realm of calming chews for dogs for a few reasons. There are so many products, which are often mixtures of various ingredients (some not even disclosed), and their studies are weak, and that’s when studies exist at all. Can these products cause harm? We simply don’t know because that’s generally not evaluated in these studies. We do know, I will add, that dietary supplements aimed at humans are poorly regulated (whenĚýthey’re not simply unregulated) and are regularly found to be contaminated and adulterated by other substances, which can cause harm. As with humans, so with pets? Quite probably.
I also heard from Robyn Lowe, the co-director ofĚý, who pointed out that even if there is evidence behind a particular ingredient, the dose used in the chew may not be high enough, or the ingredient may not be absorbed properly in the body. HerĚýĚýon the evidence behind these supplements qualifies it as “sometimes contradictory and confusing.” She also mentioned to me the larger context in which these calming chews may be thriving: a deterioration in dog behaviour in recent years, which she and her colleagues have observed. This is due to many things, including the popularity of breeds that may not flourish in every setting and owners being inexperienced when it comes to training and socializing their new pet. “I do wonder,” she wrote to me, “if people are trying to use these supplements as a Band-Aid for a much larger issue that they will never be appropriate for.”
Supplements as Band-Aids is certainly an approach I’m familiar with. So many health influencers sell dietary supplements, because being happy, getting enough sleep, losing weight, putting on muscle mass, and every ideal they promote are not easy things to get and maintain, but popping a pill is.
Lowe also pointed out something I was not aware of: the only way to legally give your pet cannabidiol (CBD) in the United Kingdom right now is to have a veterinary surgeon prescribe it. (For a deeper look into the legislation on this, I recommend .) Otherwise, giving your pet CBD constitutes .
The justification for restricting CBD use in pets in the UK is that safe dosage for use in animals—especially given different sizes—has not been established. In , veterinarians cannot, for now, authorize or prescribe cannabis products to their patients, i.e. the pets, and any CBD that is legally sold here is intended for human consumption, not for Rover’s. In the , CBD is caught in a regulatory mess; however, given Robert F. Kennedy Jr’s stated intentions to open the doors wide to pseudoscience and experimental treatments, this could change, though I would not look to the United States government for health advice moving forward.
If you are dealing with a dog that is particularly anxious, talk to your veterinarian about it. You can try calming chews if you have the money but remember that the same problems that plague human dietary supplements—the lack of robust scientific evidence for their effectiveness, the poor regulation leading to contamination, the appeal to nature used in the marketing—apply here too. It’s a dog-eat-dog world out there, and marketers are not above justifying a product’s existence with unpalatable studies.
Correction: the original version of this article initially stated that it was illegal to give CBD to a pet in the UK. CBD can actually be prescribed by a veterinary surgeon in some circumstances.
Take-home message:
- Calming chews for dogs are supplements that are claimed to help ease your dog’s anxiety
- They can contain many ingredients from a long list that includes melatonin, cannabidiol, and chamomile, and are often given an unjustified health halo because they’re sold as being “natural”
- Whether or not they are effective is unclear given how poor the scientific evidence typically is, and keep in mind that supplements are not regulated as strongly as pharmaceutical drugs, which can lead to contamination and adulteration with harmful substances
