Female dogs are not meaningfully more loyal than male dogs. The scientific evidence on canine attachment finds far more similarities between the sexes than differences, and the factors that actually shape a dog’s bond with you, like breed, early socialization, and individual personality, matter considerably more than whether your dog is male or female.
That said, there are some real, measurable behavioral differences between male and female dogs that probably feed this perception. Understanding what those differences actually are can help you see your own dog’s behavior more clearly.
What Attachment Studies Actually Show
Researchers measure canine “loyalty” using a modified version of the Strange Situation Test, originally designed to study attachment in human infants. The setup places a dog in an unfamiliar room with its owner, a stranger, and periods of separation, then tracks how the dog behaves at each stage. Most studies using this method find no significant difference between males and females in core attachment behaviors like seeking proximity to the owner, greeting the owner after separation, or showing distress when left alone.
A foundational 1998 study of 51 owner-dog pairs put it plainly: despite considerable variability in how individual dogs expressed attachment, the researchers found no effect of gender on most behavioral variables. Several follow-up studies reached the same conclusion.
However, a more recent study published in Animal Cognition did uncover some nuanced sex differences. Female dogs scored higher on sociability across all test conditions, meaning they were more interactive with both owners and strangers. Females also showed more distress specifically when separated from their owner and left with a stranger, suggesting they may be more sensitive to the absence of their primary person. Male dogs, by contrast, showed their peak distress in a different configuration: when both the owner and the stranger were present, but attention was divided.
These are real differences in how male and female dogs express attachment, but they don’t add up to one sex being “more loyal.” They point to different emotional styles rather than different levels of devotion.
The Oxytocin Connection
Oxytocin, the hormone involved in social bonding, does appear to work slightly differently in male and female dogs. In a well-known experiment led by researcher Takefumi Kikusui, dogs and their owners who spent the most time gazing into each other’s eyes both experienced significant spikes in oxytocin levels, regardless of the dog’s sex. Both males and females showed roughly a 130% rise.
The interesting split came when researchers gave dogs a nasal spray containing oxytocin. Female dogs who received the spray spent 150% more time gazing at their owners, which in turn triggered a 300% oxytocin spike in those owners. Male dogs showed no response to the spray at all. Kikusui suggested this may be because oxytocin plays a larger biological role in female mammals due to its involvement in labor and nursing. This doesn’t mean female dogs bond more strongly in everyday life, but it does suggest their bonding chemistry may be more responsive to this particular hormone.
Sex Matters Less Than You Think
When researchers try to identify what actually shapes a dog’s personality, sex consistently ranks near the bottom. A large study of 377 puppies across 12 breeds, published in Scientific Reports, tested personality traits at two months of age. Sex had no significant effect on any personality trait measured. It didn’t matter as a single factor, and it didn’t matter when combined with breed.
What did matter was breed, which explained about 10% of the variation in personality, and litter effects (meaning the specific family a puppy was born into and its early environment), which explained 23%. In other words, who a puppy’s parents are and what its first weeks of life look like shape temperament roughly three times more than breed alone, and sex didn’t register at all. The individual dog in front of you is far more important than any generalization about males or females.
Aggression and Protectiveness by Sex
Some people equate loyalty with protectiveness, so it’s worth looking at aggression data. A study of dogs in a general veterinary population found that neutered males were most likely to have bitten a household member, with about three times the odds compared to intact females. Neutered females came in second, at roughly twice the odds. Aggression toward unfamiliar people was more common overall than aggression directed at family members in both sexes.
This doesn’t support a simple “females are gentler and therefore more loyal” narrative. Aggression patterns are heavily influenced by reproductive status, not just sex. Intact dogs of both sexes tend to be bolder than their spayed or neutered counterparts, and spaying in particular has been linked to increases in possessive aggression, owner-directed aggression, and fearful reactivity in some female dogs. The picture is complicated, and protectiveness isn’t loyalty in the way most people mean it.
How Spaying and Neutering Change the Equation
Sterilization alters behavior in ways that can shift your perception of loyalty. A study published in PLOS One found 23 behavioral differences between intact and spayed female dogs. Female dogs with less lifetime exposure to their natural hormones showed higher rates of fear, anxiety, aggression, and excitability in everyday situations like hearing the doorbell, encountering unfamiliar dogs, or being approached by strangers.
On the flip side, about 53% of aggressive female dogs were reported to become more gentle after spaying. Appetite increased in about a third of spayed females. These changes can make a spayed female dog seem more dependent or attached, which owners might interpret as loyalty, when it may actually reflect increased anxiety or reduced confidence.
Male dogs show a parallel pattern. Around 61% of aggressive males became more gentle after neutering. Both sexes can appear to become more “devoted” after sterilization, but the mechanism is likely a reduction in boldness and independence rather than an increase in genuine attachment.
Why the Myth Persists
The belief that female dogs are more loyal likely comes from a few converging realities. Females do score higher on sociability in controlled tests. They are more responsive to oxytocin-driven bonding. They show more visible distress when separated from their owner. And intact females go through hormonal cycles that can produce noticeable shifts in mood and clinginess, which owners might read as devotion.
But sociability isn’t the same as loyalty. A female dog who is friendly with everyone, including strangers, is expressing a temperament trait, not a deeper bond with you. And a male dog who seems more independent may simply express attachment differently, showing peak distress in situations where he has to compete for your attention rather than when you leave the room.
If you’re choosing a dog and loyalty matters to you, focus on breed tendencies, the breeder’s track record, and especially early socialization. Spend time with individual puppies or adult dogs before deciding. The most loyal dog you’ll ever have will be loyal because of the relationship you build together, not because of what’s on its paperwork.