Sorry, I forgot to mention it earlier but.....Hi and welcome to Pet Talk!! My name is Terry and Mom to the fabulous Daisy and Delilah I don't know if this is characteristic behavior for Chis--male or female. I would love to know. I think Chis are pretty territorial, so it's quite possible. They aren't the easiest dogs to train either. No matter what you're trying to teach them. They're stubborn, head strong, and feisty, among other things Maybe their natural personalities make them like this? I'm not sure about any of it now that I think about it. I'm shocked that your Chis get along with your other dogs. My girls don't get along well with large dogs at all. Everytime they see my kid's dogs, they're so hyper and barky, I have to seperate them quickly. However, most of the time, they're pretty good girls and a pleasure to be around. I did think of one more thing. Did your girls start their original fighting when food was involved? I know D and D's first fight was over something I was eating. Even though food wasn't necessarily involved after that, the growling and "toothy grins" got worse. The only thing I usually have to do is speak to them firmly and authoritative and they stop. Believe me-I feel your pain and hope you don't have to rehome either of them. Please keep us posted and again, good luck with the problem.
p.s. Daisy gets the maddest at Delilah when Delilah tries to nicely kiss her--Delilah kisses her sister's face and Daisy's teeth come out. Delilah is a bit excessive with the "kisses"