There is a trend today in rescue, shelter work, and advocacy to call a wide variety of breeds and mixes "pit bulls" as slang; the term "pit bull" when used as slang, means absolutely nothing: it can refer to almost any short haired, blocky dog. When used in such a manner, this term is used as a label for a group of dogs comprised of what amounts to nothing more than a random sampling of the species - NOT a specific breed or even breed mix. When dogs are grouped like this, NO generalizations can be made except in terms of basic, nonspecific species behavior. When one is speaking about a purebred breed of dog, however, breed generalizations absolutely can be made - it is when speaking about a specific breed of dog that discussions about dog-directed aggression can be had, for example as in this blog post.
The one million dollar question - are Pit Bulls more prone to showing dog-directed aggression than other breeds? Is this a question that can even be answered?
This is a topic that gets debated with considerable ferocity, not just by people involved in the breed in a positive capacity, but also amongst groups and leaders who seek to ban the Pit Bull. It is a delicate topic, if only because of the anti-Pit Bull political climate, but one that must be broached and begs a moderate stance.
There are 400+ breeds. There are many types of aggression - fear, predatory (which really belongs in its own category as it is not true aggression), "dominance" (I prefer the term 'conflict aggression'), territorial, dog-directed, human-directed, idiopathic (i.e. of unknown origin), etc. There is "normal" aggression (all dogs can potentially be aggressive, and aggression is a normal and natural survival trait), and pathological aggression that is out of context and exaggerated. Also, aggression that appears in one breed may be considered pathological while that same sort of aggression appearing in another breed may be considered typical or expected. Case in point: some tendency for dog-directed aggression in Pit Bulls is not considered a fault per se, but in Goldens it is an extremely undesirable trait. As a comparison, wary, guarding-type behaviors are desired in some breeds yet in Pit Bulls would be considered huge faults in temperament.
Really, it's pretty difficult - if not impossible - to verify the validity of a statement like "This breed is 'more or less' aggressive than ALL OTHER BREEDS". There are just too many variables. We don't have "aggression genes" pinpointed yet (so we cannot simply do a genetic test), and there have been no exhaustive studies done on aggression and its manifestation within various breeds. And science has pretty much come to the conclusion that behavior is an inextricable combination of nature and environmental learning. For a complex notion like aggression (which is not a single behavior but a suite of behaviors), there are no simple answers.
What is feasible and reasonable, however, is to look at a single breed you're familiar with, and compare it to other dogs you've come across. The Pit Bull, for instance, a breed I am very familiar with and have studied since 1994. Also, as a certified dog trainer, and someone who is just plain obsessed with all things dog (especially dog behavior), I've had lots of opportunity for and actively sought to do hands-on work with a variety of breeds and have gone out of my way to observe and study behavior.
What I've observed in the breed is a high tendency to exhibit dog-directed aggression. Notice I say 'tendency to exhibit' - I am not calling the breed 'dog-aggressive', as I do not think there is such a thing as a 'dog-aggressive breed'. Dogs are not born with aggressive behavior - they learn it.
I can't prove percentage-wise or point to a study that shows that Pit Bulls exhibit a higher rate of dog-directed aggression than all other breeds (although I do believe that they exhibit a higher rate than many other breeds). This is a breed, after all, that was carefully selectively bred specifically for dog on dog combat. This is a point that cannot be ignored. Relatively few breeds were bred specifically for the unnatural purpose of fighting and doing damage to members of their own kind. To believe for a moment that your average German Shepherd (bred for herding/police work) or Golden Retriever (bred for retrieving during hunts) will exhibit the same propensity for exhibiting dog-directed aggression than the average Pit Bull will, is naïve at best and really downright dangerous at worst.
Pit Bulls often exhibit arousal around other dogs, overexcitedly seeking to interact and play with others. Their play is rough and dogs of other breeds often are overwhelmed by the play behavior of Pit Bulls. This rough play can easily escalate to the point where someone's pushed to the point of over-arousal or bitten too hard or is misinterpreted, hence a fight breaking out.
It is specifically because of a propensity for dog-directed aggression that Pit Bulls are not the breed for the average dog owner. Just as many mastiff and livestock guarding breeds were bred for a high degree of wariness towards humans and a strong tendency to exhibit aggression towards humans that are not part of their own family unit are ill-advisedly owned by the typical person in search of a dog, so is the Pit Bull very often an incorrect choice.
The irony is that Pit Bulls are an extremely human friendly breed, and any aggression towards humans is viewed as a major flaw. In fact, during the creation of this breed, there was a strong tendency to cull (eliminate from the gene pool) any dogs that exhibited human aggression. This tendency continues today, and in fact any breeder that produces "guard" or "protection" Pit Bulls or Pit Bulls with any propensity towards human aggression is shunned by the fancy at large and looked down upon.
In this society where dogs are increasingly viewed as "protectors" of home and family or as cuddly objects that are akin to live stuffed animals and expected to get along with every animal that crosses their paths, the Pit Bull is left stuck in a misunderstood middle.
When kept by a person with the wherewithal for proper management, this breed can excel at many tasks despite any propensity for dog-aggression. And this propensity can be managed and handled so as to never cause any trouble for guardian, dog or other dogs. It is mismanagement that is an increasing problem and a huge factor contributing to the large number of Pit Bull (and all dog) attacks on other members of their own species that are regularly appearing in papers across the country.
It is imperative that any person involved in rescue and placement of Pit Bulls understand the intricacies of Pit Bull behavior, particularly that of dog-aggression, so they may choose the appropriate homes and properly educate new guardians. This involves recognizing the varying degrees of dog-directed aggressive behavior that can show up in the breed, precursor behaviors, and triggers. By no means are all Pit Bulls going to show dog-directed aggression to any significant degree. Each dog needs to be evaluated as an individual while respect is also given to breed traits and tendencies as well.
Is the declaration, "Pit Bulls are dog-aggressive!" going to make the anti-Pit Bull legislators' jobs easier? There is no easy answer to this debate. But reality-based education of guardians who are ultimately responsible for the breed's future is sorely needed. No matter how often the chant of "Pit Bulls are no more dog-aggressive than any other breed!" is yelled from the rooftops, if irresponsible or naïve guardians are allowing their dogs to attack, injure and kill other dogs/animals, the chant will fall on deaf ears and the breed will continue to face outlaw status.
The best friend of the Pit Bull are guardians who are educated about their breed of choice and therefore capable handlers who keep their dogs out of trouble and out of the crosshairs of those who would ban the breed.
--Mary L. Harwelik, Certified Pet Dog Trainer; behavior & Pit Bull specialist; Founder & Director of The Real Pit Bull, Inc.