Hollywood can be ruff. (Stephen Chernin/EPA)

Movies like "Lassie" and the original "101 Dalmatians" really influenced American viewers: They both made people adopt and purchase more dogs of the breed they featured. But while we're still a bit swayed by the stars of dog-centric films, a new study in PLOS ONE reports, we just aren't as in love with cinematic canines as we used to be.

The researchers analyzed trends in dog registration around the release of major motion pictures featuring dogs in starring roles. Unsurprisingly, some films seemed to have selected their featured dog based on trending breeds of the day. But those breeds seemed to become even more popular after the film's release. And in some cases, a dog whose popularity was on a downward slide suddenly reverses that trend.

In the early years of doggy motion pictures, the influence sometimes lasted for as much as a decade. "When "Lassie" came out [in 1943], it was the only movie with a dog, so that was a big deal to people," corresponding author and Brooklyn College professor of psychology Stefano Ghirlanda said. "We can see a rise in collie registration for 15 or 20 years after its release. It was iconic, and everyone talked about it."

These days, he said, the effect still seems to be there -- but it's only a short-term phenomenon, and isn't as dramatic. "In the 40s and 50s, movies were essentially the only visual medium, so everyone was constantly going out to see them," Ghirlanda said. "Now there's so much else to do for entertainment. And in addition, we make many more movies than we did then -- and way more of them have dogs."

When "Lassie's Great Adventure" came out in 1963, registrations for the collie breed -- which had been on a decline for about a decade, finally coming down from the initial success of the first movie -- increased sharply again. The researchers found this effect impressive, since previous research had shown that the annual winner of the Westminster Dog Show had no bearing on national popularity at all.

Ghirlanda and his colleagues used data from the American Kennel Club, and only have information through 2005. But the diffusion of cinema's influence has probably continued further. Given that the "Air Bud" franchise alone has produced seven new dog movies since that year, it's hard to imagine that paws on screen carry the same weight as they used to.