This thread is amusing, to be sure. It is also a perfect example of how "news" has been replaced with headline-grabbing, ad-selling fodder. I am no crime expert, but I do know how to use Google. I could not find one ounce of "statistics" about this kind of crime, and more than one "news" article I read about this "trend" had almost a whole paragraph exactly duplicated from the "theft" section of the catalytic converters article on Wikipedia. I guess you would have to read the edit history of that article to know which came first, that section of the Wikipedia entry, or the "news" pieces.
On the other hand, you actually can find statistics online about the rate of dog theft. If someone is keeping track of dog theft, which I don't think is exactly plaguing our cities and neighborhoods, then I'm guessing catalytic converter theft is an isolated phenomenon. I don't doubt that car insurance companies keep internal statistics on different kinds of theft and vandalism, but I don't see any of these "news" pieces referring to interviews with insurance company representatives. In fact, the only articles I found that mention even having spoken to police officials are basically regurgitating anecdotes with no hard numbers.
In case you are wondering, incidents of canine abduction are a lot harder to track than vehicular vandalism, because pets aren't usually covered by a comprehensive automobile insurance policy.