New evidence recently released confirms that not only is the above statement scientific fact, it goes on to state that dudes who have dogs shorter than mid-calf have small penises.
"There is direct correlation between the size of the canine and the size of the owner's genitalia," explains Dr. Wesley O'Shannon, author of the study. "Our findings suggests that the lack of penile length prevents these men from owning a 'real' dog, one that is kick-ass and awesome. MRI's and CAT scans of these owners shows that due to extra blood in the brain, blood that would otherwise be used in a larger penis, these men cannot conprehend the fact that their dogs are retarded."
Dr. Shannon points to the follwing chart, which shows the direct connection between dog size and the owner's penis size:

The follwing are those that are not excluded from the theory, and quite obviously are accurately plotted on the above chart:
The bottom line is this: If your dog can't eat another dog, then you probably shouldn't have it.