A size match that changes the usual story
Most dog-and-cat pairings are shaped by the dog's size and chase instinct, and on both counts a Chihuahua starts with benefits. She is smaller than a typical adult cat, which removes the looming, predatory quality that unsettles cats around bigger dogs, and the breed was developed as a companion rather than a hunter, so a fleeing cat rarely triggers a serious pursuit. What a Chihuahua does bring is boldness: she will walk up to a cat she should be more cautious with, announce herself and occasionally try to claim the best bed. Cats usually answer that confidence with a measured swat, and most Chihuahuas, being clever readers of consequence, adjust their manners within a few encounters.
Introductions that protect a fragile dog
The Chihuahua's smallness cuts both ways, because a cornered cat's claws can injure her eyes or face in a single swipe. Run introductions as carefully as you would for any breed. Begin with separate rooms and scent swapping on bedding, feed them near the shared door, and let the first meetings happen with the Chihuahua on a lead and the cat free to leave or climb. Watch her body language as much as the cat's: a stiff, staring Chihuahua who fixates and trembles is over-aroused and needs more distance, not a release to say hello. Keep sessions short, end them while everyone is calm and repeat daily; a week of patient staging buys years of peace, while one rushed meeting can set the relationship back months. Clip the cat's claws before the first free meeting as a simple precaution, so an early warning swat teaches the lesson without opening a scratch on thin Chihuahua skin.
Sharing a home once they are settled
Settled Chihuahua and cat households often look charmingly equal, with shared sunny spots, mutual ignoring at mealtimes and the occasional joint occupation of the owner's lap. Protect that peace with structure. Feed them separately, because a Chihuahua will guard a bowl with theatrical seriousness and a cat who steals from it invites conflict; keep the litter tray and the cat's food somewhere the dog cannot reach, since Chihuahuas find both interesting; and give the cat vertical territory, shelves or a tall tree, so she always has somewhere the dog cannot follow. If your cat already rules the house and dislikes dogs on principle, expect tolerance rather than friendship, and plan the home so tolerance is comfortable for both.
Getting guidance as the relationship develops
Questions keep arising after the first meeting goes well: whether play is really play, when to stop supervising, how to handle a new kitten arriving in a house a Chihuahua considers hers. Those judgement calls are easier when you can check a reliable answer before deciding. Put a follow-up question to KinsLe's Kinny; he answers using the KinsLe Answers library.