To determine the value of canines to the popularity of news stories, Matthew Atkinson of the University of California, Los Angeles, and Maria Dean and Joseph Uscinski of the University of Miami, identified 18 dog-related and 334 non-dog-related stories that appeared in the national section of the New York Times since 2000. The team then checked ten other newspapers (both local and national) to see which stories got picked up the next day.
In short: A front page story in the New York Times was picked up by other papers at 3.1 times the rate of a story from the last page of the national news section. A story that involved a dog that appeared on the last page of the section appeared in other newspapers at 2.6 times the rate of a non-dog story with the same placement. In other words: "having a canine subject in a national news event produced coverage of the story that was 80% as large as the effect of the difference between being NYT front-page and back-page worthy."
It's important to note that the dog stories at issue are not "36 times cute dogs got baths" or things of that ilk. (The Times rarely runs stories on those types of topics.) The 18 dog stories that the researchers identified included dogs as essential components to actual news. "Postal Work Unfairly Maligned, Study Says," was one; "First Dog Makes His Debut," another.
That second example is offered in a rather defensive explanation of why the research has value. "How many [Americas] learned about what President Obama was doing in April 2009 as a result of the arrival of Bo, his Portuguese water dog?," the researchers ask. The answer is unknowable, but it is probably greater than one.
The researchers did not conduct any similar studies involving the use of cats. This may be because cats don't lend themselves as readily to the sorts of puns that (lamentably) are peppered throughout the research document. It may be because there are not as many news stories in which cats play a similarly prominent role. Or it may simply be due to the well-known fact that cats are worse animals than dogs. It's a mystery for the ages.