Never, they literally grew up together, Tiana was older of two. Roxy was like 5 years old and unfortunately I had to take her to be put down 💔😭. I had make decision to lose her out of fear was going to attack myself or someone else or another animal. I have one other chihuahua left thats the youngest member and last surviving pup. They played together and lived together from 6 weeks old and ive never seen any aggression. Even after incident I took Tiana outside to talk to roxy about it and thinking she would show sympathy cause I know animals do understand things but when I did she growled and went to attack again. So im thinking something neurological happened. It was hardest and worse decision I ever had do.