Basic Trope: Two species of animals all fight each other for no reason other than the fact that they're 'supposed to be enemies'.
Straight: All the cats and dogs in the series are fighting- it's seen as weird to question this.
Exaggerated: Feeling any kind of sympathy for cats will get a dog torn to shreds by his companions, because they must be murderously enemies.
Downplayed: Cats and dogs are always expected to have a little trouble getting along.
Justified: One animal is the natural prey of the other; when said other species sees the prey species, their first instinct is to hunt it.
Inverted: Two species of animals all adore each other, and to think otherwise is seen as strange.
Subverted: We see a group of cats and dogs seemingly reasonlessly fighting, but it turns out that the rest of the cats and dogs in the series get along just fine.
Double Subverted: We see some cats and dogs fighting, and then we see some of them being friends as well, until the ones that are friends are ridiculed by their peers for such atrocious behavior and sympathizing with the enemy.
Parodied: All dogs hate the musical Cats and relentlessly attack advertisements for performances.
Zig Zagged: And when it gets down to the last few, they make up. But the truce is broken again after one leader's makes fun of the other's dead father. Repeat ad infinitum.
Averted: Some animals hate each other for perfectly logical reasons, and do not war against one entire species in particular.
Enforced: It's a kids' show, and it'd be a bit silly to be explaining the moral and social reasons for every cat chasing a mouse in the background, so they just keep any reason out.
Lampshaded: "Oh look, Sparky's chasing the cat for no reason again."
Invoked: A strangely intelligent dog figures he'll go chase some cats, because that's what they're expected to do, even if it is pointless.
Defied: A friendly dog decides to give cats a chance, and not to hate them pointlessly like is expected.
Discussed: "Hey, I wonder why Buddy keeps chasing the neighborhood cats- does he even have a reason to hate them?"
Conversed: "Why can't cats and dogs ever stop fighting and get along in those movies?"
Deconstructed: The reasonless war between the species continues to brutal extents, all for no point, and eventually both sides are beyond the point of no return. The last of each species is left fighting still, both elderly and frail. When one finally kills the other, he finally has time to ask why.
Reconstructed: They start making progress recovering the species before the point of no return, but one leader makes fun of the other's mother, and all out war starts again.