Are Dog Stereotypes Real?
There are heated arguments on both sides of this issue. A 2008 article in the journal Genetics sheds some light on the question.
Investigators studied 148 breeds, looking for markers that might control behavioral stereotypes: herding, pointing, excitability, boldness, and trainability. Using dogs showing extreme examples of these characteristics they were able to tentatively identify the associated genes. More significant were the associations they found for characteristics like dog size and breed longevity with other specific genes.
While the results are not conclusive and there are plenty of examples of tame pit bulls and vicious collies, it is reasonable to believe that some breeds are more likely to display undesirable behaviors that need to be taken into consideration when selecting a dog for adoption.
The behavioral stereotypes for each breed can be viewed by downloading supplemental table 1, which is available here: http://www.genetics.org/content/179/2/1033/suppl/DC1
The full article can be read online at http://www.genetics.org/content/179/2/1033.full.pdf+html
Single-Nucleotide-Polymorphism-Based Association Mapping of Dog Stereotypes Genetics June 2008 vol. 179 no. 2 1033-1044