These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
It's more tearjerker-y if you've had dogs. Especially if you tend to project emotions onto them.
Even more especially if you've had a dog put down or die in some way.
Why doesn't anybody ever write a pet memoir while the animal in question is still alive?
The Other Darrin : Multiple dogs play the part of Marley, which is common in Hollywood because often each dog performs a different trick (running, chewing, barking, etc.), and because Marley is shown as a puppy, an adult, and a senior dog. However, they don't even TRY to disguise the very different looking Retrievers who play Marley, resulting in a jarringly different appearance between the adult and senior dogs.