The dog pounces at the cat, stopping short, directly in her expressionless face. He thinks he’s fulfilling his role as a tough-guy mongrel, a canine Cagney, intimidating his housemate, the ice-cool kitty. They lock eyes and stand nose-to-nose. She doesn’t flinch, budge or blink. She has seen him coming, fast, and she holds her ground, not a single whisker aquiver.

The dog, Cubby, is small. The cat, witheringly, seems to be saying to him, “You’re too short for that gesture,” as George Saunders tells Anne Baxter when she swings open the door and tries to eject him from a room in “All About Eve.” In the end, the dog capitulates, and the cat sashays away.

For the most part, the animals, including another cat, coexist impressively peaceably. They are very mature about their roommate situation. Drama is minimal, and, when it happens, laughable. No one gets hurt.

Poor Cubby. He’s all bark and no bite (except in play, when he nips fiendishly). He loves to hear himself yap, yelp and yowl when the mail carrier mounts the porch, producing a piercing cacophony and, somewhat comically, a rousing display of feckless theater. He growls, spins and crouches, a shrimp-size showman, his nails doing a fine tap dance on the wood floor.

Yet open the door when someone rings and he clams up, giddily sniffing the newcomer, tail wagging, a bundle of excited curiosity. The animal is operating on pure instinct, doggie DNA, so we try not to make fun.

The house cats, Tiger Lily and Spicy, tolerate Cubby, despite their frequent sighs. They mostly ignore him and his occasional manifestations of machismo. They are unflappable, standoffish. Basically, they don’t give a shit. And when they do, they swipe a samurai paw at his face. He recoils.

Yet sometimes he gets their goat. Periodically, he will chase one of them up the stairs and the cat will bolt, scramble, fly. But not without emitting a long hiss, like a leaky tire or a king cobra. Cubby doesn’t relish that sound, and he stands down and returns to worrying one of his irresistible bully sticks (which are actual 100% bull penises, dried and seasoned).

The whole cats and dogs as mortal foes narrative is a hoary myth. Of course some dogs antagoznie some cats. (As a kid, our otherwise dreamy black Lab tore apart the neighbor’s cat in a scene out of “Cujo.”) It’s nothing personal. It’s biology and psychology: genes and instincts run amok.

There’s a fluffy black cat in the neighborhood that ambles right up to Cubby when he’s on his walks, and the animals casually sniff each other out, the cat practically rubbing against the dog, purring. Cubby is mostly indifferent to this, and promptly moves on.

But he can’t help needle his pet-mates in the house. Close proximity, boredom, jealousy, general annoyance — many reasons spring to mind, all of them conjecture. Sometimes he gets feisty when a cat gets too close to his bully stick, as if they’ll snatch it. Other times he’s just asserting his virility, his wishful doggie dominance.

The cats and the dog are in many ways classic shotgun roommates: imperfect fits, possessive, a little irritable, eating each other’s food, each from different worlds. One roommate likes rap, the other likes Rachmaninoff. The cats want their space, Cubby wants to invade it. He wants to be the pack leader, the alpha male honcho. It’s sad yet funny.

Don’t tell Cubby, but it’s pretty clear: Tiger Lily could lick him.