In this article

1. What oxytocin does
2. The 2015 study behind the headlines
3. Why the loop is still in question
4. What later studies found
5. Why oxytocin is so hard to pin down
6. Tears at the front door
7. What it means for you and your dog

Your dog is stretched out on the sofa. They lift their head, find your eyes and hold them, and you hold theirs back. It is one of the small, warm moments of life with a dog, and the internet has an explanation ready: you are both getting a rush of oxytocin, the so-called love hormone.

That explanation grew out of a real and striking study. It is also less settled than the headlines suggest. Here is what the oxytocin research found, where it wobbles, and what it means for the time you spend with your dog.

What oxytocin does

Oxytocin is a small molecule, a chain of just nine amino acids, with important roles in sex, giving birth and feeding young¹. In people it has also been linked with attachment, with recognising others and with how we treat our own group compared with outsiders¹. In a number of other species it plays a part in the bond between mothers and young, and between mates¹. Hence the nickname.

Before 2015, several studies had found that owners' oxytocin, measured in their blood, rose after they stroked, played with and talked to their dogs¹. Then came the study that made a dog's gaze famous.

The 2015 study behind the headlines

In 2015 a Japanese team watched owners spend 30 minutes with their dogs and recorded how long each dog gazed at its owner^{2, 6}. They measured oxytocin in urine from owners and dogs before and after¹. Owners whose dogs gazed at them longest showed a rise, and so did those dogs, while hand-reared wolves and their owners, tested the same way, showed no such rise^{2, 6}.

In a second experiment the team gave dogs a nasal spray of oxytocin, then recorded how the dogs' behaviour changed and what that did to their owners' oxytocin⁶. From the two experiments they proposed a loop: a dog's gaze lifts its owner's oxytocin, the owner becomes more affectionate, and the dog's oxytocin rises in turn². They suggested it may have helped dogs and people grow close during domestication². It is a lovely idea. Look at the detail, though, and it rests on rather few dogs.

Why the loop is still in question

By one later team's count, only 8 of the 30 dogs tested, the long gazers, showed the rise¹. Another group re-analysed the original data and found a twist. Oxytocin rose in women owners, of dogs and wolves alike, while in men it stayed flat or dipped slightly⁶.

The dog owners were 82% women and the wolf owners 55%, so the owners' sex offers another explanation for the gap between dogs and wolves⁶. That fits other work: in one small study, 8 of 10 women but none of 10 men showed a rise in oxytocin after time with their own dog¹. The dog-versus-wolf comparison of gazing and oxytocin also rested on just 28 dogs and 11 wolves, and the re-analysis team concluded that a loop shaped by domestication 'is not yet justified'⁶.

Wolves raised like dogs

In 2021 a team in Austria put the wolf question to a direct test. They compared 11 dogs and 10 wolves that had all been hand-raised and lived in packs at the same research centre, so their experience of people was alike⁷. After five minutes of petting at the fence from the person who raised them, or from a familiar person, neither the dogs nor the wolves showed an oxytocin rise⁷.

Pet dogs told a different story. In 10 pet dogs tested with their owners, the more time a dog spent in physical contact with its owner, the higher its oxytocin, which was not the case with a familiar person⁷. The researchers concluded that life as a pet dog, more than domestication itself, accounts for the oxytocin response⁷.

What later studies found

Away from the wolves, the everyday question is simpler: does friendly attention raise a dog's oxytocin? So far the answer is sometimes.

In a 2017 study in California, 38 young Labradors and Labrador-golden retriever crosses training as assistance dogs either spent 10 minutes in friendly, free-form contact with a researcher or rested quietly in the same room³. Saliva oxytocin rose by 39% in the dogs given attention, with no significant rise in the resting group, while the rise in blood was a modest 5.7%³. The more contact, play and licking, the bigger the rise in saliva, though the authors described the study as exploratory³.

Two years later, a team in Vienna gave 20 dogs and their owners, all women, a 15-minute cuddle of gentle stroking, talking and eye contact¹. Neither the dogs' oxytocin nor the owners' changed consistently, and only 8 of the 20 dogs showed a rise of more than 10%¹. Given the mixed record, and the risk that studies finding nothing never get published, the authors wrote that oxytocin's role in the bond 'might be currently overrated'¹.

Study	Who took part	What happened
Japan, 2015	30 dogs, 11 hand-reared wolves and their owners1, 6	Oxytocin rose in long-gazing dogs and their owners, but not in wolves2, 6
California, 2017	38 young assistance dogs in training3	Saliva oxytocin up 39% after 10 minutes of friendly contact3
Austria, 2019	20 dogs and their owners, all women1	No consistent change after a 15-minute cuddle1
Austria, 2021	11 pack dogs, 10 wolves and 10 pet dogs7	No rise in pack animals; pet dogs' oxytocin tracked time in contact with their owners7

Why oxytocin is so hard to pin down

Part of the problem is that nobody can easily sample a dog's brain. Studies measure oxytocin in urine, blood or saliva instead, and whether those levels reflect what is happening in the brain is still debated^{1, 4}.

The tests disagree, too. Different laboratory kits can give quite different readings for the same sample, and when the Vienna team re-measured stored samples months later, the values had shifted with no consistent pattern¹. Urine adds a snag of its own: dogs do not usually empty their bladders completely, so a fresh rise can be diluted by what was already there¹.

Different methods may explain some of that spread, but the reviewers found that studies using similar methods still disagreed⁴. The saliva work does point one way: in all three reviewed studies that gave dogs 5 to 10 minutes of controlled, friendly contact, saliva oxytocin went up⁴. Even then, one study's result changed with the choice between two laboratory tests⁴.

Tears at the front door

A more recent twist comes from the Japanese group behind the 2015 study⁸. In 2022 they measured dogs' tear volume with an eye test called the Schirmer tear test, before and after the dogs were reunited with their owner or with a familiar person who was not their owner⁸. Tear volume went up on reunion with the owner and not with the other person⁸.

Oxytocin solution dropped into dogs' eyes increased tears too, and people rated photos of dogs more positively when artificial tears had been added⁸. The researchers suggest tears like these may help dogs and people connect⁸. Keep it in proportion: the study measured tear volume, and a wetter eye is not the same as a dog weeping with joy.

What it means for you and your dog

None of this makes the bond any less real. Studies have found that dogs use their owner as a secure base, much as children do with a parent: they explore and play more with their owner there, and do better at a problem-solving task with their owner present than with a stranger¹. What is still unclear is the chemistry behind it.

The research does hint that how your dog feels about the contact matters. In one saliva study, dogs that did not relax while being stroked, or disliked having their saliva sampled, showed a fall in oxytocin instead of a rise⁴. So treat a soft, relaxed look as an invitation, and let your dog decide how long the cuddle lasts⁵.

So keep sharing that look on the sofa. The science cannot yet promise it tops up anyone's oxytocin, but a dog who chooses to meet your eyes, and then stays put, is telling you plenty already.

Sources and further reading8 sources

The small numbers in the article link to the source behind each fact. Sources open on their own websites.

1. The Role of Oxytocin in the Dog–Owner RelationshipAnimals (MDPI)
2. Oxytocin-gaze positive loop and the coevolution of human-dog bondsScience
3. Effects of Affiliative Human–Animal Interaction on Dog Salivary and Plasma Oxytocin and VasopressinFrontiers in Psychology
4. A Scoping Review on Salivary Oxytocin and Vasopressin Measurement in the DogAnimals (MDPI)
5. How to understand your dog's body languageDogs Trust
6. Commentary: Oxytocin-gaze positive loop and the coevolution of human–dog bondsFrontiers in Neuroscience
7. Life experience rather than domestication accounts for dogs’ increased oxytocin release during social contact with humansScientific Reports
8. Increase of tear volume in dogs after reunion with owners is mediated by oxytocinCurrent Biology