My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
Dogs are opportunistic by nature. If they figure out a way of getting something like affection or avoiding doing something by acting a certain way, they will repeat the behavior to get their way. So while she may have been abused or be scared of the leash, if you continue to not use a leash because she acts that way, it reinforces the behavior. I know it is going to be difficult for you, but you need to get a leash on her. Just put a short 4 foot leash on her and let her drag it around the home. You might need to get her in a small area initially to get it on her but then don't cave in. Keep it on her.
At that point, ignore her. She may just stay in one place and not move, but sooner or later if you ignore her, she'll move if for no other reason then to eat or drink. Once she moves, you can give her calm praise and maybe even a special treat like a hot dog sliver to encourage her moving with the leash on. It won't be a quick cure, but she'll get used to having the leash on. She'll see that nothing happens to her when she has the leash on and won't be a scared of it.
Once she is ok with the leash you can practice leading her around with the treats as lures to get her moving with the leash in your hand. This part should go pretty quickly and then you can take her outside. Don't overwelm her outside. Many small dogs have had bad experiences outside such as birds swooping down on them or even being attacked by other dogs and thus they might not like going outside. So you need to keep her safe when she is outside and ensure she doesn't have any bad experiences with other dogs when she is outside. This would be the time where having a helper dog she is ok with go on short walks with you.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer.