I have an older female boxer mix. She was a stray so not sure of her age but would guess 7 years old, she is spayed. She seems to be getting grumpier than a few years ago. She has less tolerance for our 3 year old Saint and other dogs-she does not to play unless it is on her terms. My neighbor has 2 spayed females and they do not get along well. I think part of the problem with the neighbors dog is that there is no established hierarchy. She is not in pain or ill, she is great with the kids and the other animals in the house. But not pleased with trimming her nails. I am wondering if her increasing age is a factor?