Much then comes down to the owners, and therein lies the real problem.
Scarlett indicated that at least one study is underway to see if certain factors predict if a segment of the population is at greater risk for being attacked by a dog.
Anecdotally, socioeconomic factors, whether or not a dog has been spayed or neutered, and whether or not a dog has been socialized and trained, appear to predict attacks. Many tragedies happen in homes where one member has a puppy mill-bred pit bull, Rottweiler, mastiff, or other dog and the unsupervised canine attacks a toddler.
Jennifer Lu, communications manager at the SF SPCA, said that pit bulls may have a bad reputation now, but other dogs, such as Doberman pinschers and German shepherds, held that dubious distinction in past decades. Some breeders then would try to create more aggressive versions of those dogs in response to demand.
Due to such problems with breeding, many shelters are waging campaigns against puppy mills that put profit ahead of the welfare of dogs. Aggressive canines aren't the only outcomes either. Owners desiring unusual or distinctive looking dogs, such as applehead Chihuahuas, may not realize that breeders are "exploiting a genetic defect that may cause the skull not to close," according to Lu. "This leaves many of the dogs with a soft, unprotected part of the head."