I have 3 dogs. My chihuahua is male and constantly pees on the carpet. He will go into the bathroom to poo. He first asks to go outside, but if we are not quick, then, well, it is too late. He is 11.
My poodle is male and completely housebroken, will not ever go in the house, carpet or not. He is 2.
My lab is female and has never gone in the house. She was housebroken on her first day! she is 3.
I have heard male chihuahuas are the worst about housebreaking. The two I have had were awful.
I have had a female chihuahua that never went inside.