It’s not unusual for dogs to get cranky when they age.. Especially when deafness or blindness set in. They become unsure of their ability to protect/defend themselves and can lash out. This isn’t so bad if the dog is a chihuahua, but many of the FIGHTING dog breeds end up put down or in shelters because their owners become fearful of them. Another thing to consider before owning a dog.
I know someone who had a chihuahua that turned into Satan in his old age.. went partially blind and deaf.. poor thing was always on the defensive, bless his soul. But his owner understood this and never punished the dog. But if this dog had been a Pitt Bull, one has to consider the fatal consequences.
I have experienced this as well. I had another Chow, a mix, named red dog. I also adopted this guy off the hard streets of New Orleans, however, he was much nicer than the other chow.
I had red dog for 9 years before he started to go down hill. He was basically just a big, red lump that sat on the carpet all day, but then he got bad cataracts, and started to go blind. As a result, anytime anyone passed him up, he would bite out at them as they passed, snapping teeth, but he would miss everytime. He just didn’t know who it was next to him.
This type of aggression was never in his personality prior to losing his sight. One time, while I was out of town, my mom had come to feed him, and he growled at her. This, sadly, was all I could allow.