I got my rat terrier and my chihuahua when they were both just 8 weeks old. They were raised together since 9 weeks old and get along great.
Prior to them being one year old, I took them to dog park every weekend in order to ensure that they get proper socialization around other dogs.
when they were 2 years old, I had relocated from their birth city and adopted 2 cats. There was no fuss from the 2 dogs, they accepted the cats and life was good. However, due to the fact that the closest dog park to the new home is an hour drive, we frequented the dog park significantly less, once a month now.
Lately (within the past year) I have begun to notice that my rat terrier is showing more and more aggressive behavior toward strangers (whether it is children, other dogs, other adults). She was always skittish by nature by I have yet to see her act so aggressive toward other dogs in the dog park. As soon as they come for a sniff she growls and bites the air toward them. Meanwhile my chihuahua is accepting it quite differently, he comingles with other dogs and sniffs them right back.
I am confused as to why my two dogs are reacting so differently to new dogs at the new dog park. I don't know what is causing this and I would really appreciate any feedback.