New dog is attacking our cats

How old is Sadie?

Toy dogs need a lot of socializing from day one in order to become well-rounded non-reserved individuals. Chihuahuas can turn into the biggest nightmare without proper socialization.

Her behavior to me seems "typical" meaning I hear that a lot about little dogs (even dogs in general). Dogs like to chase (of course not all dogs, my dog looks at a squirel and just goes hmm that's funny looking and moves on)

A question I heard a lot during my rescue was "how are they with cats?"

Look at how dogs play with one another even. They wrestle and run and chase each other.

There are "proper" ways of introducing a dog & cat (many many books on it) I think you should look into that and go back to square one.

I would first do some research about proper cat & dog introduction. And if need be, find a local trainer to assist you with the processes.

We also do have some trainers here on the forum; hopefully you can get a variety of tips from them as well.

I would also start working on Sadie to learn "wait" or "stay" or "leave it" and commands that won't allow her to "chase". That way if she does begin to get anxious you can correct her by saying "ah! leave him alone..." and she'll know what that means.

Eventually they will be used to each other too

Stop the problem in the beginning, before it escalates. When she starts even LOOKING at the cat, call her to you, sit/stay. Leash her if need be. Keep her leashed, allow her to sniff the kitty, sit/treat. Make the kitty a positive thing, not a toy.

Does the cat have a safe place? My cats have higher up places to escape dogs that want to "play". Their food is on the counter in the kitchen, where the dogs can't get to it. They also have a cat door to get onto the porch.

What several people I know have done is cut a hole in a closet door - for the food, and litter box. Since you have a small dog - this may or may not work. My smaller dog is afraid of the cat door - so he doens't bother with it (he doesn't chase the cats either....).

And in regards to the food - do you free feed? If not - feed the dog in the crate, or someplace where the cat will not wander past. My own dog is possesive of food around other animals (cats and dogs) so to eliminate problems, he is fed in my room, where the are no other animals. When I have fosters, they are fed in the crate.

i had a problem similar to this, but my little one just wanted to play, no to actually hurt them... altho sometimes play got a little too rough in the cats opinion lol

i had one cat who defended himself, and one who ran. when Zoey would chase them, i'd say "no chasing!" and grab her by the collar and have a time out of five minutes. it gave the cats time to run into the basement (where Zoey doesn't go), or wherever they felt safe.

I stayed consistent and it didn't take long for her to understand, when mommy says no chasing, she means it. Now, they are all ok together, even tho sometimes the cat who ran doesn't want to play as much as the one who defended himself. in fact, the defender is more the problem now! he'll go over to Zoey and wave his bum in her face then run away, or gets jealous when we're snuggling the dog and wants to cut in. i let them all run around together, but only when i can tell that the cat is ok with it. if it gets too much, i give out a "leave it" (that we taught in conjunction with the no chasing, and use it also for things she's not supposed to get into- usually pieces of paper that fall on the floor she likes to shred)

my non-expert advice is teach a good "leave it" or "no chasing"... be consistent! and seek the help of a professional if things don't start going better.

Good luck! keep at it, because you shouldn't have to chose cats OR dogs :)