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Are Male Dogs More Aggressive Than Females?

Sex differences in canine aggression are more complicated than you might think.

Beliefs about dog behavior often arise because we generalize from our observations and beliefs about human behavior. In humans the statistics are clear. Males are more likely than females to be involved in physical aggression and are more likely to do physical harm during an aggressive event. Men are also more likely to engage in violent criminal behavior and to opt for careers in which they may encounter violence, such as the military or law enforcement. Many people simply extrapolate from this and attach the facts associated with humans to dogs. Thus most people seem to believe that female dogs make better pets. Dog breeders report that it is quite common for potential buyers to specifically request a “sweet girl.”

As in the case of humans, however, science does not find that the issue of sex differences in aggression is simple and always predictable when it comes to dogs. Evidence suggesting that male dogs are more aggressive is consistent with the fact that aggressive behavior can be triggered by testosterone, the principal male sex hormone. In dog versus dog aggression, it is true that male dogs do posture, threaten and challenge each other more than females, though this is largely ritualized display aimed at establishing social rankings. While it can be disturbing and embarrassing to the respective owners, serious injuries to the dogs are rare.

Female dogs threaten less frequently, but overall are more independent, stubborn, and territorial than their male counterparts. The females are actually much more intent upon exercising their dominance and while males can forgive an occasional transgression of canine protocol or a failure to recognize their status, females do not. This explains why actual fights are more likely to break out between two females and these often occur without much advance warning. These fights between females are more of a “no holds barred” affair rather than the male ritualistic fighting that includes snapping at the air in front of the opponent or using inhibited bites to threaten rather than to maim.

In dog aggression toward humans, which is of far greater concern to all, it is true that unneutered males are more likely to be involved in biting incidents. Furthermore, since male dogs are larger, such bites can be more serious. A study commissioned by the U.S. National Center for Injury Prevention and Control looked at lethal dog bite cases and found that male dogs were 6.2 times more likely to fatally bite someone, and sexually intact dogs were 2.6 times more likely to be involved in attacks than are neutered dogs.

Most human bite incidents in pet male dogs involve issues of leadership and control between the dog and the human, but as in dog versus dog aggression there is usually ample warning and many threats before anything physical occurs. Both male and female dogs are equally likely to threaten or bite if the issue is possession of a food or a cherished object. A female is less likely to wage a dominance battle that escalates into aggression with a human, but females can be cunning and resourceful in getting their own way, and in the human mind they are often perceived as being more “sneaky” than male dogs.

Female dogs that have just given birth will aggressively defend their puppies from anything that might threaten them. This is a completely unrestrained use of force, since a canine mother will do anything to protect their litter. Early socialization to a variety of different people will reduce the likelihood of such aggression when the female has a litter.

Unfortunately, there is an additional, little-known complication in female dogs that seems to set them apart from wild canines and other domestic animals. Whether they are pregnant or not, after ovulating all unaltered female dogs go through a two-month period in which their body is flooded with the same hormones that are present during pregnancy. For some dogs, this will even result in physiological changes that mimic pregnancy, such as lactating. The problem is that in the last three or four weeks of this phantom pregnancy the female may start acting in a strange manner about certain items, such as tennis balls, socks, soft toys, or shoes. Typically she collects these and hides them under a bed or other piece of furniture. Furthermore, she might become quite possessive and protective of these items and snap, growl, or bite anyone who comes too near or disturbs them. As with dogs with actual litters, however, well-socialized dogs are less prone to this behavior. However, as in the case of male aggression, the only real preventive measure is early neutering.

If this problem does occur in your female dog, behavioral methods won’t cure the aggression. Hormone treatments can eliminate it, or you might simply wait the situation out, since it will usually disappear in a few weeks by itself. However during the time that this form of aggression is likely, isolating the dog might be best. At the very least, you should keep children or non-family members from approaching that pile of toys, since the dog is treating these as her litter and will protect them as fiercely as she would protect her real puppies.

Stanley Coren is the author of many books, including Born to Bark; Do Dogs Dream? The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; and more.

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission.

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