Another reason why dogs stop coming when called :

Imagine you start taking Tikeya to the dog park every Friday. When you're ready to leave, you call her to you, put her leash on and leave. After about the 3rd or 4th Friday, she stops coming.

From her eyes, every time she is called, she's receving something negative - going home. Playing with the other dogs is much more fun so she starts to ignore her recall word.

In a case like this, I would periodically call my dog to me, hold her collar and praise her for a minute, then reward her by letting her go back and play. Its important that they don't always expect something negative to happen.

I'm wondering if Tikeya is on any medicine or anything. Like, do you call her to you a lot then give her medicine, or another unpleasant experience? If thats the case, you might want to simply go get her at those times instead of calling her. Or if you do call her, give her an extra special treat before and after the medicine or whatever else she doesn't like.

Changing your recall word will help immensely.