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鈥檛 simply say, 鈥渢here鈥檚 a study behind this, therefore it must work.鈥� Studies have flaws, and bad studies can be propped up to sell you a product that will only separate you from your money.
鈥淎s above, so below,鈥� 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鈥檚 melatonin, the hormone many animals produce when it鈥檚 time to go to sleep, as well as cannabidiol (CBD), a molecule found in cannabis (including hemp) and which has been decorated with听an array of dubious health claims. But you will also find chamomile, passionflower, valerian root, gingko biloba, L-theanine, ashwagandha, casein, L-tryptophan,听Bifidobacterium longum,听magnesium, 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 鈥渘atural.鈥� 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 鈥渘atural,鈥� right? Well, there鈥檚 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鈥檚 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, 鈥渘atural鈥� 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鈥檚 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鈥檛 earned.
Pet peeve
Here鈥檚 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鈥檚 cheap, easy, and unlikely to cause harm, so it gets sold as a calming chew听as part of a whole behavioural training regimen to teach dogs how to deal with anxiety.听And when their pet鈥檚 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鈥檚 a scientist鈥檚 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鈥檛 have the time or inclination to run trials with their pet to see if it鈥檚 the calming chew that鈥檚 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 thinks听that the supplement worked when it didn鈥檛.
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 a听听of alpha-casozepine (Zylkene), a derivative of milk, sponsored by the supplement maker and comparing it to anti-anxiety medication鈥� 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 a听听done in healthy dogs of a supplement containing polyphenols, prebiotics, and omega-3 fatty acids鈥μ�where anxiety was not even assessed. Instead, the scientists measured molecules in the blood that have been linked to anxiety.
And here is a听听often cited to support the use of a bacterium,听Bifidobacterium longum,听to help with dog anxiety, but it鈥檚 a conference talk from a team working for Nestl茅 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: Nestl茅, their parent company, made roughly USD 100,000,000,000 in听听(that鈥檚 one hundred billion dollars鈥� I had to look it up). They just don鈥檛 need to. Most consumers will buy anything so long as it鈥檚 labelled as natural, and many of the remaining skeptics will be swayed by allusions to studies and won鈥檛 scrutinize them.
Even a听听of the state of our knowledge on this issue鈥攁 review which is听very kind听to the quality of the evidence鈥攃oncludes that these supplements should be used at the same time as a series of modifications to the pet鈥檚 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 McKenzie runs the听, and in 2019 he wrote about听听he was able to find for Purina鈥檚 Calming Care Probiotic for Anxiety in Dogs supplement, which is supposed to alter your dog鈥檚 gut bacteria to 鈥渟upport calm behaviour.鈥� 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 that听
In his email to me, McKenzie warns that it鈥檚 difficult to give a deep evaluation of everything that鈥檚 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鈥檚 when studies exist at all. Can these products cause harm? We simply don鈥檛 know because that鈥檚 generally not evaluated in these studies. We do know, I will add, that dietary supplements aimed at humans are poorly regulated (when听they鈥檙e 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 of听, 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. Her听听on the evidence behind these supplements qualifies it as 鈥渟ometimes contradictory and confusing.鈥� 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. 鈥淚 do wonder,鈥� she wrote to me, 鈥渋f people are trying to use these supplements as a Band-Aid for a much larger issue that they will never be appropriate for.鈥�
Supplements as Band-Aids is certainly an approach I鈥檓 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鈥攅specially given different sizes鈥攈as 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鈥檚. In the , CBD is caught in a regulatory mess; however, given Robert F. Kennedy Jr鈥檚 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鈥攖he lack of robust scientific evidence for their effectiveness, the poor regulation leading to contamination, the appeal to nature used in the marketing鈥攁pply here too. It鈥檚 a dog-eat-dog world out there, and marketers are not above justifying a product鈥檚 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鈥檚 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鈥檙e sold as being 鈥渘atural鈥�
- 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
