We started with Joker (pitbull/sharpei mix), who would show interest in the cats, and chase them when they ran, but would show no aggression - just a strong desire to play. Our one male cat (we have three indoor cats, two male, one female) would actually get mad and worked up enough to chase the dog, NOT playing, which the Joker LOVED, even as he ran for his life from the spitting and growling cat. Joker also loves the neighbor's dogs, and, for that matter, every dog he's met, as well as other cats, such as the one at the vet's office.
And then we got Daphne. Daphne is a two year old female demon trapped in a small 50 pound pitbull body. She is a loving and devoted dog, very good with people and kids, even if she's only happy when she's trying to climb into your lap to lick and chew on your chin. She does not for an instant accept a "no, get down" - she KNOWS you really want her on your lap, licking your face, and nibbling. She spent the first two years of her life being ignored and starved, locked away in a crate with not much interaction. After she was used as evidence to prosecute her former owners, she was sent to a kill shelter, where we found and rescued her. She is ok with the neighbor's male shihtzu, but is VERY aggravated by their massive female German Shepherd puppy (80 pounds at 8 months, beautiful dog, has a head that looks like a horse). When she goes out into our yard, she patrols the fence, looking for the neighbor's dogs. Fortunately, we always both look for each others' dogs before we let them out in the yard, so interactions are few and far between. When they happen, it's all very loud barking and carrying-on, but no trying to attack through the fence. I'm convinced that a few good walks with the neighbor's dog would settle the issue and they'd be friends (Joker loves the dogs), but the neighbor is in her 80's and doesn't seem inclined.
Daphne has quite a prey drive. She's already caught and killed one rabbit in our backyard. I fully expect additional rabbits and squirrels to follow. She's a quick beast. Joker, on the other hand, likely wouldn't know what to do with a rabbit if he saw one. When we go to the pet store, Daphne shows great interest in the caged rabbits and cats, and loves to watch them, but she doesn't try to get to them. Domestic critters are pretty safe, wild critters are food.
After we got Daphne, Joker now shows zero interest in the cats. He's all about his new sister, even though she firmly puts him in his place when she needs to. She is definitely the alpha dog between them, which we expected - Joker is a very submissive dog. He just wants to play and be chased and have fun, which he gets plenty of with Daphne.
Daphne, on the other hand, is VERY fascinated by the cats. Often when she approaches one of our cats, the cat won't even know she's there. She is quiet, head down, very focused, and walks slowly and calmly up to the cat. It is unnerving to see her like this - she reminds me of a predatory cat herself when approaching in this manner. Often, the first time the cat even knows she's there is when he feels Daphne's breath on the back of his/her neck. At that point, things go one of two ways - the cat bolts and runs upstairs, with Daphne in hot pursuit (always the female cat), or the cat looks at her and holds his ground, either ignoring her (in which case Daphne just stands there, VERY close, watching with great interest), or the cat hisses and smacks her (Daphne always backs off), or, as has happened numerous times, the cat will begin to purr and rub against Daphne's face or body. When this happens, Daphne always wags her tail and gives a doggy smile, and usually walks away.
Daphne's approach is hugely dependent on her energy level. If she just came in from outside and is wound up, or if she and Joker were throwing each other around the living room, forget the quiet and predatory approach if a cats shows up - she hauls ass and goes after the cat, in which case the cat will ALWAYS run like hell upstairs - thus encouraging the chase. Again, usually a sharp word will bring her back down, but not always - if she corners the cat, nothing comes of it - she just stands there over the pissed-off cat. Usually the cat will just go under a bed, where Daphne won't fit. If the cat is up ON the bed, Daphne will hop up and stand over the cat, just staring. Intently. Very intently. Again, "Daphne, leave it!" or "Daphne, NO!" will bring her back with a goofy "I'm sorry" expression on her face. Sometimes a light tap on her butt is enough to take her attention from the cat; a treat always works, too. That sweet and innocent "I'm sorry" expression is ALWAYS on her face, especially when she's doing her damnedest to climb into your lap to lick your face.
Now, we don't just sit there and watch, obviously - we like our cats alive and kicking. Usually a sharp word and Daphne backs down and comes away from the cat. Also, when we're sleeping, or when we're away, both dogs have their crates - no dog is EVER alone with the cats.
While we trust Joker, he is what he is, and because of his instinct to chase (even if in play), we know that Daphne is
a very real threat, and she could set him off if she decided to actually do some damage. So far, so good, and the treat-training/vigilance/crate use continue.
Joker on the left, Daphne on the right:
Daphne, "I'm sorry!":