I'll be repeating some. I love a LOT of dog movies.
-My Dog Skip
-Call of the Wild
-Marley and Me
-Beverly Hills Chihuahua
-Turner and Hooch
-All the Lassie movies- the original trilogy (with Son of Lassie and Courage of Lassie) and the later remakes, too.
-Fluke (I didn't think I'd like it because animal-that's actually-a-man movies usually aren't the best made, but I loved it)
-Lady and the Tramp
-The Fox and the Hound
-Old Yeller (though the book was much better)
-Where the Red Fern Grows (the book was also much better)
There are way more, though.