Dog owners understand the reality all too well: a dog's only fault is that they leave us far too soon. Well, some are absolutely vicious menaces to society, but for most dogs, the whole passing-away-too-soon thing is by far their worst feature.
So, owners of puppies and dogs long in the tooth avoid these movies at all costs. They might start sweet, but they turn out to be unmitigated bummers.
Even Owen Wilson, in his prime, couldn't out-goofy the ending to Marley & Me. Those who read the best-selling novel that preceded the film still went to see this movie knowing that they'd need a Shop-Vac to suck up the tears.